Systems and methods of manually assisted movement for spatial alignment lengthwise measurements in intravascular ultrasound imaging

Abstract

The systems and methods described herein are directed towards methods of measuring distances along vasculature with intravascular ultrasound imaging. Several embodiments advantageously do not rely on fully automated co-registration with another imaging modality, such as angiography, radioscopy, or fluoroscopy. More specifically, a processor may detect a longitudinal movement of the catheter based on a detection of markers disposed on the catheter based on pacing inputs provided by the user and / or pacing instructions output to the user by the system corresponding with marker movement. The processor can associate and annotate IVUS images with a longitudinal position of the markers at the time the IVUS images are captured. Encoders may also be deployed to reduce dependence on another imaging modality.

Description

EVID.017WO PATENT SYSTEMS AND METHODS OF MANUALLY ASSISTED MOVEMENT FOR SPATIAL ALIGNMENT LENGTHWISE MEASUREMENTS IN INTRAVASCULAR ULTRASOUND IMAGING REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. U.S. App. 63 / 531,266 filed August 7, 2023 titled “Systems And Methods Of Manually Assisted Pullback For Spatial Alignment Lengthwise Measurements In Intravascular Ultrasound Imaging” which is hereby incorporated by reference in its entirety, herein. BACKGROUND Field

[0002] The present disclosure relates to the field of ultrasound, such as using ultrasound for diagnostic and imaging applications for medical purposes. Description of the Related Art

[0003] Ultrasound imaging transducers, including those used for intraluminal imaging, emit and receive acoustic waves in order to produce an image based off reflections from objects near the ultrasound transducer, such as tissue. Some standard IVUS catheters rely on motorized axial translation with accessories such as motors and translation mechanisms to facilitate the measurement of lengths and distances across IVUS images across an intraluminal axis between imaged tissue features. SUMMARY

[0004] Intravascular ultrasound (IVUS) imaging is provided in multiple embodiments that for example, includes manually assisted longitudinal movement of an IVUS catheter for spatial lengthwise alignment measurements of tissue using IVUS imaging, such as distance-based length measurements along an intraluminal axis within a patient. Movement, such as longitudinal movement and / or axial movement, comprises pullback or pulling back a catheter from a vessel or other lumen, pushing or otherwise advancing a catheter into a vessel or other lumen, or both.

[0005] Diagnosis, measurements, and imaging of intraluminal tissue are critical in identifying irregularities, disease, and / or injury for medical treatment and can improve patientoutcomes. Measurements of dimensions (e.g., length, width, thickness) of intravascular lesions such as plaque (e.g., hard plaque, soft plaque, vulnerable plaque, calcified plaque, substantially non calcified plaque) or thrombus, facilitate diagnosis and preparation for deploying stents, and is useful for planning of treatment by medical practitioners, e.g., physicians, surgeons, and / or medical technicians in various fields, such as vascular surgery and / or interventional cardiology throughout the body from the heart to the peripheral vasculature. In several embodiments, intravascular imaging-guided percutaneous interventions in arteries and / or veins for peripheral vascular or coronary lesions is achieved through the use of the IVUS imaging improvements described herein. Imaging, measurement, and diagnosis of intraluminal (e.g., intravascular, cavity, digestive tract, esophagus, stomach, intestine, rectum, sinus, ureter, bladder, gynecological, cardiac etc.) tissue assists in identifying irregularities, disease, and / or injury for medical treatment to improve patient outcomes. After identification of irregularities, appropriate treatments may be used on the patient. For example, image-guided treatment of tumors, thrombus, plaque, etc. may be used in which imaging and therapeutic capabilities exist on a single device or multiple devices. Several embodiments include, for example, percutaneous coronary intervention for coronary artery lesions, intravascular imaging-guided percutaneous intervention for peripheral vascular lesions, and / or intravascular imaging-guided percutaneous interventions in arteries and / or veins. In several embodiments, the IVUS system is configured for optimized peripheral vascular procedures. In several embodiments, the IVUS system is configured for optimized peripheral vascular procedures and is not configured for coronary vascular procedures. In several embodiments, the IVUS system is configured for coronary procedures. In several embodiments, the IVUS system is configured for neurovascular procedures (including but not limited to cerebral vessels). In several embodiments, the IVUS system is configured for intravascular ultrasound-guided thrombectomy, including but not limited to mechanical thrombectomy. In some embodiments, the IVUS system is configured for ultrasound-guided pulmonary embolectomy. In several embodiments, simultaneous, real-time IVUS guidance is provided for procedures such as thrombectomy / embolectomy, stent placement, clot aspiration, other coronary or neurovascular procedures, etc. Although several embodiments described herein described IVUS, the technology described herein are also used for intraluminal imaging (other than intravascular). For example, several embodiments are used for imaging, diagnosing, and / or providing animage-guided intervention in the digestive tract, esophagus, stomach, intestine, rectum, sinus, ureter, bladder, uterus, fallopian tubes, lungs, brain, etc. The systems and methods described herein may be used in conjunction with an endoscope rather than an IVUS catheter and support identification and diagnoses of gastrointestinal tumors, such as tumors in the intestines and / or biliary ducts. Similarly, the systems and methods described herein may be used to image a sinus cavity using IVUS. In various embodiments, IVUS uses ultrasound for imaging only (without therapy). In various embodiments, IVUS uses ultrasound for therapy only (without imaging). In various embodiments, IVUS uses ultrasound for both imaging and therapy. According to several embodiments, one or more imaging technologies as described herein can be combined on the same catheter as one or more therapy elements, such as an integrated ultrasound imaging element located at or near the tip of (or otherwise along) a thrombectomy device. The thrombectomy device can also be a separate device that is delivered before, during or after the imaging device. Thrombectomy devices can be mechanical clot retrieval devices, clot aspiration devices, or a combination of clot retrieval and aspiration. Neurovascular, coronary and pulmonary clots are treated in several embodiments using the ultrasound imaging devices and methods disclosed herein together with (either integrated or separate) clot treatment devices. The clot treatment device can also include for example non-mechanical devices such as lytic or other drug delivery devices and energy delivery devices to disrupt / remove the clot or otherwise restore blood flow. Combinations of two, three or more therapies combined with the IVUS imaging technologies described herein are also provided (for example, ultrasonic or laser clot disruption with a lytic agent). The integrated IVUS and therapy catheter or probe can also be used, according to several embodiments, for restoring blood flow that is not caused by a clot.

[0006] Several embodiments described herein provide systems and methods for determining a lengthwise, longitudinal position of a manually advanced and / or retracted ultrasound imaging catheter and measuring the length of a longitudinal, lengthwise movement of the ultrasound imaging catheter within a blood vessel, lumen, or other region. Manually assisted longitudinal, lengthwise movement of an IVUS catheter may be implemented for spatial alignment measurements of tissue using IVUS imaging. In several embodiments, distance-based length measurements along an intraluminal axis of a patient are provided, suchas measurements of vascular lengths using distance-based measurement along the vascular axis.

[0007] Several embodiments provide relative position along an axial and / or longitudinal catheter dimension during sequentially acquired IVUS images within a human vessel using manual translation of a catheter with efficient clinical workflow. The position information allows for measurement among images acquired during translation with respect to the longitudinal dimension of a catheter without use of a bulky device in the sterile field to actuate movement (e.g., pullback or advancement) of the catheter.

[0008] Advantageously, several embodiments described herein do not require fully automated co-registration with another imaging modality such as fluoroscopy, in which a software algorithm tracks radio-opaque (RO) catheter marker(s) or a RO transducer throughout a continuous fluoroscopy recording. In several embodiments, systems and methods for IVUS based measurements do not require integration with another imaging modality and reduce fluoroscopy exposure to the patient. Consistent operator-to-system or system-to-operator interaction may be more reliable than a software and / or an image-based recognition system for RO markers where weak signals or poor-quality signals may limit accuracy. Co-registration with angiography is used, for example, in an attempt to shorten procedure time, decrease contrast use, and make practitioners more comfortable with IVUS. Described herein, are several embodiments that accomplish one or more of these benefits without co-registration. In some embodiments, use of the manual movement helps correlate fiducial landmarks and waypoints within a patient’s body, including in complex cases, such as dimensional measurements of tissue damage, occlusions, lesions for treatment planning, such as atherectomy or stent placement (e.g., determining where in a vessel stenting will be begin and end). Although co-registration is still available with the systems and methods described herein, the ability to measure the dimensions of intravascular lesions without automated co- registration may allow for more flexibility to use different components (e.g. components that may be more readily available to physicians and / or components for which physicians already have a level of comfort). Increased speed of procedures, reduced cost of medical care, and better patient outcomes may be accomplished in many embodiments.

[0009] Several embodiments of image registration described herein utilize synchronized operation and / or measurements from two or more imaging modalities (e.g.,ultrasound, X-ray (including radiography, fluoroscopy, angiography, etc.), magnetic resonance, PET scans, optical imaging (e.g., optical coherence tomography, light, laser imaging), etc.) in order to track the position of an intraluminal catheter with a second imaging modality to determine the relative position between respective images in a series from both the intraluminal catheter and the second imaging modality. In several embodiments, a user of an IVUS catheter identifies waypoints and fiducial landmarks and interacts with the IVUS system via inputs or outputs (e.g., voice commands, sounds, tones, beats, vibrations, touches, button clicks, etc.) to synchronize measurements of tissue in alignment with a second imaging modality. In several embodiments, measurements are synchronized without using one or more of the following: (i) automated computer software that communicate with multiple imaging modalities to identify and track the position of an IVUS catheter to remove reliance on user interaction, (ii) an automated process via direct uniform, linked communications between the imaging modality devices.

[0010] In some embodiments, use of the manual movement helps correlate fiducial landmarks and waypoints within a patient’s body, including in complex cases, such as dimensional measurements of tissue damage, occlusions, lesions for treatment planning, such as atherectomy or stent placement (e.g., determining where in a vessel stenting will be begin and end).

[0011] Fractional flow reserve (FFR) is a minimally invasive procedure used to determine the extent of stenosis (narrowing) of coronary arteries by measuring the blood pressure and flow in coronary arteries. The Instantaneous wave-free ratio (iFR) index used to assess the severity of coronary-artery stenosis by measuring the pressure ratio during a specified period of diastole when the coronary resistance is relatively minimized and stable. Both FFR and iFR measures have been found to have similar diagnostic accuracy. According to some embodiments, IVUS imaging and iFR (instantaneous wave-free ratio) and FFR (fractional flow reserve) can be used to identify lesions and other areas of interest with or without co-registration.

[0012] In several embodiments, intraluminal measurements use imaging to capture images to diagnose, measure, and plan for treatment of a variety of diseases and conditions. In several embodiments, IVUS catheter systems are used to capture images to diagnose, measure, and plan for treatment of a variety of cardiovascular diseases and conditions. An importantdata point in assessing a cardiovascular pathology with an IVUS system is the position of the transducer(s) at the time the image is captured. More specifically, several embodiments described herein permit a physician to be able to determine a longitudinal position of the IVUS catheter and the length or distance of a longitudinal movement (e.g., pullback or advancement) of the IVUS catheter within blood vessels.

[0013] Advantageously, several embodiments described herein permit effective and efficient use of IVUS without bulky accessories, such as motorized pullback device with translation mechanisms that automatically control the lengthwise, longitudinal or translation movement of the catheter within a lumen (e.g., blood vessels). Other advantages in some embodiments include decreased cost, complexity and procedure time, because (i) automated length measuring accessories may increase the cost and complexity of use of the IVUS system and the time it takes to prepare for a procedure; and (ii) motorized pullback devices are typically positioned within the sterile field and must be sterilized prior to the procedure or wrapped / bagged in sterile material. Further, an automated pullback device can decrease the amount of refined control and the range of motion a physician has during the procedure when compared to IVUS systems that do not employ a motorized pullback device. Several embodiments herein do not impair refined control. In several embodiments, the manual movement measuring device and methods do not involve a position sensor device, such as an encoder, for measurement of linear motion. In several embodiments, the manual movement measuring device and methods do not involve mechanically assisted, automated pullback using telescoping catheters at pre-programmed rate or selection of rates, such as a driven mechanical unit that provides motion actuation and position encoding and / or a telescoping catheter provides a particular path for the axial motion of the imaging core during automated mechanical pullback. Several embodiments described herein provide systems and methods that provide sufficient accuracy to assist with clinical decisions without objects that must reside in the patient sterile field. Advantages of several embodiments include a reduction or elimination of workflow difficulties, and a significant reduction of setup time, effort, and complexity for intraluminal measurements.

[0014] In various embodiments, a manual movement measuring technique is employed using the methods and systems disclosed herein. In one embodiment, manual manipulation involves control of the position of the IVUS catheter by hand, such as one handin a glove. In several embodiments, the manual movement measuring device and methods do not involve powered or automated translational motion, axial and / or longitudinal motion, or linear motion, without telescopic components, without a motor for linear motion, or a tool engageable with the IVUS catheter for pullback out of or for advancement into the patient.

[0015] In various embodiments, systems and methods are described for detecting a longitudinal and / or lengthwise position and movement of a manually advanced or retracted catheter. Advantageously, these systems and methods, in several embodiments, provide for more efficient manual control over the position of the catheter while measuring lengths within a blood vessel or other lumen with the ultrasound imaging catheter. In some embodiments, the systems and methods provide for automatically annotating IVUS images with longitudinal position information such as the position, speed, or a length of a longitudinal movement. Several embodiments described herein remove the guesswork associated with manually advanced IVUS catheters and improve workflow of correlating IVUS images to position within the body by for example by reference to a second imaging modality. In turn, physicians can more efficiently provide patients with more reliable or accurate diagnoses and treatments, improving patient outcomes.

[0016] Although use of IVUS without translation mechanisms and encoders that automatically control the longitudinal lengthwise and / or translational movement of the catheter within a lumen is provided in many embodiments, alternate technology is also provided herein. Examples of such alternate technology include an IVUS image series capture recording while manually retracting, extracting, inserting or advancing a catheter along the vessel while relative or absolute insertion depth of the catheter is measured and recorded by an axial / longitudinal translation position measuring device at or near the location of catheter insertion to the patient’s body. In various embodiments, the axial translation position measuring device is an encoder. The encoder can be, for example, one or more of a mechanical, optical, inductive, magnetic, electromagnetic capacitive, linear, absolute, incremental, single channel, incremental, square wave, and / or other position sensing device. In one embodiment, spatial position of the images along the vessel length in the series will be estimated using the insertion depth data. With this data, an image series may be rendered against a length axis. With this spatial alignment, a spatially realistic volume dataset (e.g., two-dimensional or three- dimensional image of radial / diameter versus axial length which can be referred to as a “strip”image) may be created and displayed. In one embodiment, the image series may be rendered and displayed against a longitudinal lengthwise axis, longitudinal lengths, or distances between relevant positions in the series. Distances between anatomical points of interest can be obtained with sufficient accuracy and detailed IVUS images aiding clinical therapy decisions such as preferred balloon lengths for percutaneous transluminal angioplasty and / or expandable stent lengths.

[0017] According to various embodiments, methods of measuring a lengthwise distance between a series of images that are captured while an intravascular ultrasound (IVUS) catheter is moved by hand include moving the IVUS catheter along a longitudinal axis of the IVUS catheter with a hand, wherein the IVUS catheter comprises a plurality of markers disposed along a length of a longitudinal axis of the IVUS catheter at a predetermined spacing, wherein the plurality of markers are visible by a complementary imaging modality. The method can include capturing a plurality of images with the complementary imaging modality while moving the IVUS catheter in a proximal direction or a distal direction along the longitudinal axis of the IVUS catheter. The method can include capturing with a recording device, one or more position inputs from a user that indicate a position of at least one of the plurality of markers relative to an anatomical point. The method can include associating the one or more position inputs with the plurality of images based on the position of the plurality of markers at a time each image of the plurality of images was captured. The method can include determining a longitudinal distance between the one or more images based on the predetermined spacing between the markers. The method can include determining an estimated longitudinal position for each of the plurality of images by interpolating the longitudinal distance.

[0018] In some embodiments, the plurality of markers are uniformly spaced by a uniform spacing distance in a range of 1 – 5 cm (e.g., 1.5 cm, 2.5 cm, 3 cm, 4.5 cm, 5 cm, and any values and ranges therein). In some embodiments, the plurality of markers are uniformly spaced by a uniform spacing distance in a range of 2 to 50 mm (e.g., 2.0, 3.0, 4.0, 5.0, 10.0, 15.0, to 50.0 mm, and any values and ranges therein). In some embodiments, the plurality of markers are uniformly spaced by a uniform spacing distance in a range of 2 to 50 mm (e.g., 2.0 mm, 3.0 mm, 4.0 mm, 5.0 mm, 10.0 mm, 15.0 mm, 20.0 mm, 25.0 mm, 30.0 mm, 40.0 mm, 50.0 mm, and any values and ranges therein). In various embodiments the one or moreposition inputs are (i) provided by the user speaking a single word as each of the plurality of markers passes the anatomical point, (ii) individual spoken words associated with a progress of each of the plurality of markers passes the anatomical point, (iii) involve pressing a button, (iv) involve tapping the IVUS catheter or a catheter interface module, and / or (v) involve stepping on a foot pedal. In some embodiments, the method includes providing a visualization of the plurality of images with a distance based lengthwise axis, measuring / reporting the longitudinal distance between two sequential images of the plurality of images, and / or measuring / reporting a distance between two or more images of the plurality of images. In one embodiment, the complementary imaging modality is X-ray fluoroscopy, wherein the plurality of markers are seen in the fluoroscopy progressing past the anatomical point, and wherein the plurality of markers are seen directly progressing past an introducer sheath, a guide catheter, or some other fixed point outside the body.

[0019] According to various embodiments, methods of measuring a lengthwise distance between a series of images captured while an intravascular ultrasound (IVUS) catheter is moved by hand can include inserting an IVUS catheter into a patient. The IVUS catheter can include a catheter body, one or more ultrasound transducers disposed within the catheter body, and one or more markers disposed longitudinally along the catheter body. The method can include receiving one or more movement reporting inputs from a user and determining, via a processor, a length of the longitudinal movement based on the one or more movement reporting inputs, wherein the longitudinal movement is caused by a manual movement of the catheter body. The one or more movement reporting inputs can include one or more of a speech input, a mechanical input, a touch input, or a combination thereof. In one embodiment, the movement reporting inputs provide a unidirectional movement, longitudinal movement rate and / or a reference position, wherein the reference position corresponds with an anatomical position of the catheter body relative to the patient. The markers can be one or more bands disposed on an external surface or inserted within the catheter body, and can optionally be radiopaque. The method can detect an error condition (such as an incorrect marker order, a repeated marker, a missing marker, or a non-uniform detection of the one or more markers).

[0020] According to various embodiments, an intravascular ultrasound (IVUS) catheter system that is configured for detecting a longitudinal position includes a catheter body configured to be disposed within a lumen of a vessel of a patient, one or more markers disposedalong the catheter body, and a processor configured to receive one or more movement reporting inputs from a user, determine a lengthwise movement based on the one or more movement reporting inputs, and provide an output to a user based on the longitudinal movement. The one or more movement reporting inputs may include one or more of: a speech input, a mechanical input, a touch input, or a combination thereof. The markers can include one or more bands disposed on an external surface of or inserted within the catheter body, the marker can optionally be radiopaque. The system can detect an error condition (such as an incorrect marker order, a repeated marker, a missing marker, or a non-uniform detection of the one or more markers).

[0021] According to various embodiments, methods of measuring a lengthwise distance between a series of images captured while an intravascular ultrasound (IVUS) catheter is moved by hand can include moving the IVUS catheter along a longitudinal axis of the IVUS catheter with a hand, wherein the IVUS catheter comprises a plurality of markers along a length of a longitudinal axis of the IVUS catheter, wherein the plurality of markers are visible by a complementary imaging modality. The method can include providing a plurality of pacing outputs to a user based on a programmed movement rate and storing a plurality of images of a series of positions of the plurality of markers relative to an anatomical point, and determining an estimated longitudinal position for each of the plurality of images based on the programmed movement rate. The method can also include (i) measuring / reporting the longitudinal distance between two sequential images of the plurality of images, (ii) measuring / reporting a distance between two or more images of the plurality of images, (iii) prompting the user to accept or reject the estimated longitudinal position for each of the plurality of images, and / or (iv) providing a visualization of the plurality of images with a distance based lengthwise axis. In various embodiments the pacing outputs are audible, haptic, and / or visual. In some embodiments, the plurality of markers are uniformly spaced by a uniform spacing distance in a range of 1 – 5 cm (e.g., 1.5 cm, 2.5 cm, 3 cm, 4.5 cm, 5 cm, and any values and ranges therein). In some embodiments, the plurality of markers are uniformly spaced by a uniform spacing distance in a range of 2 to 50 mm (e.g., 2.0, 3.0, 4.0, 5.0, 10.0, 15.0, to 50.0 mm and any values and ranges therein)

[0022] According to various embodiments, methods of measuring a lengthwise distance between a series of images captured while an intravascular ultrasound (IVUS) catheteris moved by hand can include inserting or retracting an IVUS catheter into a patient. The IVUS catheter can include a catheter body, one or more ultrasound transducers disposed within the catheter body, and / or one or more markers disposed longitudinally along the catheter body. The method includes providing one or more pacing instructions to a user and determining, via a processor, a length of a longitudinal movement of the catheter body based on the one or more pacing instructions, wherein the longitudinal movement is caused by a manual movement of the catheter body. The one or more pacing instructions can dictate a rate of unidirectional movement by the user, and the rate can be in a range of 1 – 20 mm / sec (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20 mm / sec, and any values and ranges therein). In some embodiments the method includes receiving the rate from the user, collecting IVUS images, and / or annotating the IVUS images based on the longitudinal movement of the catheter body. In various embodiments the pacing outputs are audible, haptic, and / or visual.

[0023] According to various embodiments, an intravascular ultrasound (IVUS) catheter system configured for detecting a longitudinal position includes a catheter body configured to be disposed within a lumen of a vessel of a patient, one or more markers disposed along the catheter body, and a processor configured to provide one or more pacing instructions to a user, determine a length of the longitudinal movement based on the one or more pacing instructions, and / or provide an output to a user based on the longitudinal movement.

[0024] Additionally, in several embodiments, the systems and methods do not require co-registration with another imaging technique, such as angiography, the moving the IVUS catheter with the hand is accomplished without using a linear actuation motor, and / or the IVUS catheter does not comprise a telescoping component.

[0025] In various embodiments, a method of measuring a lengthwise distance between a series of images captured while an intravascular ultrasound (IVUS) catheter is moved by hand can include moving the IVUS catheter along a longitudinal axis of the IVUS catheter with a hand, capturing a plurality of images with the IVUS catheter while moving the IVUS catheter in a proximal direction or a distal direction along the longitudinal axis of the IVUS catheter, measuring a distance travelled by the IVUS catheter with means for encoding, associating an image or tissue feature in the plurality of images with the distance travelled by the IVUS catheter, and determining a longitudinal length between images or of the tissue feature based on the distance measured by the means for encoding. Means for encoding forincluding can comprise or consist essentially of, for example, an encoder not associated with a mechanical actuator or motor. In various embodiments the means for encoding is mechanical, optical, inductive, and / or capacitive (or combinations thereof). In various embodiments the encoder is disposable and smaller than existing non-disposable motorized pullback units that require a sterile bag / cover before placement in the sterile field. The encoder unit may be attached to the introducer sheath or guiding catheter at the entry point into the patient so it doesn’t take up much space in the sterile field. In other embodiments the smaller encoder is not disposable and can easily be re-sterilized by autoclaving for frequent re-use.

[0026] In various embodiments, an intravascular ultrasound (IVUS) catheter system configured for detecting a longitudinal position, the system including a catheter body configured to be disposed within a lumen of a vessel of a patient; one or more markers disposed along the catheter body; and means for measuring a rate of movement of the one or more markers when, for example, the catheter body is moved longitudinally by hand; and provide capacity to measure / report an output length or lengths to a user based on the movement of the catheter body by hand. Means for measuring can comprise or consist essentially of an encoder, position sensors, alignment device, etc.

[0027] In several embodiments, the technologies described herein, including the catheter technologies for example, are used with other medical imaging systems (such as cardiac catheterization lab systems), to provide an integrated healthcare portfolio for cardiologists. An integrated or otherwise coordinated platform, in several embodiments, can improve workflow between various imaging systems, including for example, x-ray systems. In one embodiment, stent placement and other procedures (e.g., thrombectomy, clot retrieval, balloon placement, etc.) are optimized using the IVUS technology described herein together with x-ray, external ultrasound and / or other non-IVUS technology.

[0028] In several embodiments, the IVUS technologies described herein are used with other catheter-based imaging procedures and / or non-catheter-based imaging procedures. Imaging procedures may include ultrasound, x-ray, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), PET-CT, fluoroscopy, endoscopy, angiography, optical coherence tomography, intravital microscopy, 2D imaging, 3D imaging, etc. Several embodiments described herein utilize synchronized operation, imaging, and / or measurements from two, three or more imaging modalities (e.g., ultrasound,X-ray (including radiography, fluoroscopy, angiography, venography, etc.), magnetic resonance, PET scans, optical imaging (e.g., optical coherence tomography, light, laser imaging), etc.). Multi-modality synergies between IVUS and one or more additional imaging systems are achieved in several embodiments, including for example, enhanced visualization and image quality, decreased procedure time, increased precision in stent positioning and vessel measurements, improved workflow and reliability, and other benefits. Multi-modal systems including IVUS may be used, for example, to allow cardiologists to diagnose and / or treat vascular blockages and other defects that should, in turn, offer patients with improved cardiac outcomes, while reducing the overall cost burden to the healthcare system through efficient and effective integration with IVUS. A more robust image of vessel and organ structures (such as heart structure) can be obtained using various embodiments of the IVUS technologies described herein.

[0029] In several embodiments, catheters are optimized for vascular imaging are configured for superior pushability, tracking, and crossing for arterial and venous peripheral vasculature. In several embodiments, one or more of the following features are provided:

[0030] Pushability: In several embodiments, catheters have superior pushability to avoid kinking with sufficient column strength to advance the catheter through tortuous bends and occlusions in vasculatures without buckling, over bending, or collapsing anywhere along the catheter (e.g., proximate or (e.g., ability to cross an occlusion or constriction). Material properties in some embodiments (e.g., balance of rigidity and flexibility, durometer in various segments), dimensional characteristics (e.g., larger dimensions, such a diameter and thickness, increase column strength, account for greater pushability and kink resistance.

[0031] Tracking: In several embodiments, catheters have superior tracking for the ability of the catheter to follow a guidewire through tortuous bends in vasculature, having sufficient flexibility and strength to move along and advance along a guidewire to target locations within the vasculature. Hydrophilic coatings according to some embodiments help reduce friction with guidewires and the surrounding luminal tissue. In various embodiments, hydrophilic coatings are on an external surface and / or an internal surface (e.g., in a lumen, etc.) of the catheter. In some embodiments, hydrophilic coatings are not on an external surface of the catheter. In some embodiments, hydrophilic coatings are not on an internal surface (e.g., in a lumen, etc.) of the catheter.

[0032] Crossing: In several embodiments, catheters have superior crossing capabilities to cross occlusions, restrictions and constrictions within the vasculature, such as at sites with tissue blockage (e.g., stenoses, etc.) and / or implant blockages (such as stents, balloons, etc.). According to some embodiments, crossing ability is enhanced by one or more of the following: (i) design of the distal tip (e.g., pointed enough to navigate occlusions, etc. and blunt enough not to snag on an occlusion), (ii) material properties (e.g., balance of rigidity and flexibility, durometer in various segments, etc.) and / or (iii) dimensional characteristics (e.g., larger dimensions, such a diameter and thickness, increase column strength). In one embodiment, low durometer near the distal tip is provided for flexibility to navigate tortuous anatomy and obstructions. In one embodiment, a region of varying or step wise gradient changes to a higher durometer proximally sufficient to push the catheter while avoiding kinking is provided. A single durometer and / or flexibility can remain constant along a certain or all portions of a device.

[0033] In various embodiments, a kit is provided comprising one, several or all of the following one or more catheters, components, encoders, connectors, as described herein, as well as instructions for use.

[0034] Artificial intelligence and / or machine learning (AI / ML) are employed in some embodiments to enable and / or enhance measurements and / or image interpretation using the technologies described herein. In one embodiment, the system is matched for high definition (e.g., HD, UHD, HD+, etc.) image quality using acoustics and signal processing customized for peripheral vascular imaging with enhanced resolution and / or penetration. Several embodiments are configured for intravascular imaging with a platform that is optimized for peripheral and / or coronary vascular procedures that will enable improved image interpretation, intervention guidance, and enhance ease of use and improve overall usability to streamline intraprocedural and clinical workflow. In several embodiments, the system improves usability with a contemporary system featuring a simplified user-interface and enhanced total-system capabilities leveraging AI to streamline workflow and image interpretation. In several embodiments, the systems described herein, including for example the advanced intravascular ultrasound platform, leverage Artificial Intelligence (AI) to enable image interpretation, enhance total-system capabilities, and streamline workflows to maximize the clinical value. In some embodiments, advantageously, physicians will not need to integrate(e.g., cognitively integrate) imaging data spatially and temporally to fully interpret the clinical condition. Instead, systems according to several embodiments described herein can leverage the power of AI with generational advancements to go beyond single image interpretation. In several embodiments, the AI-powered engine, for example, may include a workstation that enhances image interpretation with a simplified workflow improving overall useability. Machine learning is used in several embodiments. In one embodiment, the AI-ready processing power is designed to support real time and on-demand image interpretation. The AI powered workstation can provide high end processing and an AI engine for advanced signal and image processing. In various embodiments, the native image data capture provides for superior image interpretation (e.g., border detection, identification and measurement of vessel size, vessel disease, dissection, plaque morphology, etc.). In several embodiments, the systems described herein provide simplified measurement via automated border detection (e.g., AI algorithms automatically identify borders of a lumen, vessel, tissue, lesion, plaque, etc.). In several embodiments, the system provides simplified measurement via semi-automated border detection (e.g., the user can manually adjust or modify automated AI algorithms that identify borders of a lumen, vessel, tissue, lesion, plaque, etc. with the border selection reconfigured based on user modifications). In one embodiment, AI plaque identification utilizes AI algorithms to automatically classify and identify types of plaque within the imaged area to provide user guidance on treatment options (e.g., using color coding, icons or text overlays can be used to indicate what type of condition, such as plaque, may be present for the selected image). In several embodiments, the data driven platform is designed to collect data, simplify image interpretation, with AI processing power to support real time and on-demand image interpretation and reduce user cognitive load to help (i) identify lumen size, (ii) visualize dissections, (iii) characterize disease morphology, (iv) locate and quantify stenosis, and / or (v) identify true lumen. In some embodiments, image interpretation is used to identify thrombus, thrombosis, clots, embolisms, plaque, calcium, tissue health, stent or balloon apposition, and / or stent or balloon “health” or condition. Image interpretation may involve imaging to evaluate quality and / or position of placement of an existing stent. Image interpretation can involve identifying position relative to lumen walls, determine level of and / or quality of tissue grown into and around the stent or balloon. In one embodiment, for example with a bioresorbable stent, image interpretation can involve (i) evaluating the amount of dissolving of the stent, (ii)determining if the dissolving of the stent is in accordance with expected decay patterns (e.g., determining whether the level of decay on one side of the stent similar to the other side of the stent, and if not, that may indicate a problem with stent placement, or if the stent is dissolving more rapidly than expected that could indicate the stent will not provide the tissue with the expected structural support). High-fidelity ultrasound data is used in one embodiment to drive improved image generation and image interpretation, with the option for leveraging artificial intelligence and / or machine learning. In various embodiments, catheters, devices, systems, and methods may be configured for use in performing edge-based machine learning computations associated with an image and / or image analysis using an artificial intelligence algorithm to identify one or more of a tissue border, plaque, calcium, thrombus, dissection, and / or stent apposition.

[0035] In various embodiments, the IVUS catheter is configured for imaging (alone or in combination with therapy) tissue and / or plaque (e.g., any one or more of hard plaque, soft plaque, vulnerable plaque, calcified plaque, substantially non calcified plaque). In various embodiments, the IVUS catheter is configured for imaging thrombus. In several embodiments, the technologies described herein are used for one or more of the following: identification of thrombus, dissection, calcium severity, vessel measurement, and / or preprocedural and postprocedural planning. In several embodiments, the technologies described herein are used to guide the sizing of stents, identify stent placement, apposition and / or expansion, assess lesion morphology, vascular wall thickening, loss of luminal patency, and / or vascular insufficiency, quantify plaque burden, identify complications from procedures, and / or evaluate stent failure with stent thrombosis or in-stent restenosis. The technologies described herein can distinguish between lipids, calcified plaque, and tissue proliferation. In many embodiments, better imaging detail is provided than, for example, angiography.

[0036] As used in the summary above, as well the description below, where a device or a method “comprises” or “includes” (the two being interchangeable) certain features or steps, such device or method may also “consist essentially of” some of those features or steps if identified as such (i.e. recites “consists essentially of” in the claims).

[0037] The technology described herein is used in several embodiments with flush- less, encapsulated seal IVUS catheters to reduce air bubbles and eliminate need to flush acoustic coupling fluid including the technology described in U.S. Patent Serial No.63 / 459,312 entitled Systems and Methods for Flush-Less Intravascular Ultrasound Catheter and U.S. Patent Serial No. 63 / 546,091 entitled Systems and Methods for Flush-Less Intravascular Ultrasound Catheter, and the PCT / US2024 / 024045 application claiming priority thereto and filed April 11, 2024. The technology described herein is used in several embodiments with intraluminal image focusing with spinning single element ultrasound transducer via modification of image (e.g., angular diffraction, phase, amplitude, time shift, compositing backscatter reflected images) including the technology described in U.S. Patent Serial No. 63 / 497,962 entitled Spinning Single Element Ultrasound Transducer and Focusing Methods and the PCT / US2024 / 024035 application claiming priority thereto and filed April 11, 2024; and ultrasound imaging systems and components, voice control, and artificial intelligence algorithms including the technology described in U.S. Patent Serial No. 63 / 546,058 entitled Systems and Methods for Intravascular Ultrasound, all herein incorporated by reference in their entirety into the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The following drawings are for illustrative purposes only and show non- limiting embodiments. Features from different figures may be combined in several embodiments.

[0039] Fig. 1 is a block diagram of a lateral cutaway view of an intravascular ultrasound (IVUS) system according to an embodiment.

[0040] Fig. 2A illustrates the polar plane of a polar coordinate system relative to a catheter body according to an embodiment.

[0041] Fig. 2B illustrates an isometric view of the polar coordinate system shown in Fig. 2A according to an embodiment.

[0042] Fig.2C depicts a series of IVUS images and a strip image thereof according to an embodiment.

[0043] Fig.3 is a block diagram of a lateral view of an IVUS system with markers according to an embodiment.

[0044] Fig. 4A illustrates an example process for measuring a longitudinal movement of an IVUS catheter system according to an embodiment.

[0045] Fig.4B depicts an example process for measuring a longitudinal movement of an IVUS catheter system according to an embodiment.

[0046] Fig.5A depicts an example process for measuring a longitudinal movement of an IVUS catheter system according to an embodiment.

[0047] Fig.5B depicts an example process for measuring a longitudinal movement of an IVUS catheter system according to an embodiment.

[0048] Fig. 6A is an X-ray image demonstrating the positioning of a plurality of markers relative to a fiducial point according to an embodiment.

[0049] Fig. 6B is an X-ray image demonstrating the positioning of a plurality of markers relative to a fiducial point according to an embodiment.

[0050] Fig. 6C is an X-ray image demonstrating the positioning of a plurality of markers relative to a fiducial point according to an embodiment.

[0051] Fig. 6D is an X-ray image demonstrating the positioning of a plurality of markers relative to a fiducial point according to an embodiment.

[0052] Fig. 7 is a chart illustrating lag in translation between translation at a catheter point of insertion into the patient compared to translation at the catheter tip according to an embodiment.

[0053] Fig. 8 illustrates an embodiment of a relative insertion depth measurement device using a mechanical encoder.

[0054] Figs. 9A and 9B illustrate an embodiment of a relative insertion depth measurement device using an inductive encoder.

[0055] Fig. 9C illustrates a schematic circuit diagram of an inductive encoder according to an embodiment.

[0056] Fig.10 illustrates an embodiment of a relative insertion depth measurement device using an inductive encoder.

[0057] Fig.11 illustrates an embodiment of a relative insertion depth measurement device using an optical encoder.

[0058] Fig.12 illustrates an embodiment of a relative insertion depth measurement device using a mechanical wheel encoder. DETAILED DESCRIPTION

[0059] Described herein, are multiple embodiments that do not rely on automated co-registration with another imaging platform (such as X-ray fluoroscopy or angiography) to perform effectively and efficiently. Several embodiments permit shortened procedure times,decreased contrast use, refined control, and flexibility to measure tissue (e.g., lesions, calcifications, etc.) within a body lumen without requiring co-registration. Although automated co-registration is still feasible with embodiments described herein, the removal of any required reliance on automated co-registration is particularly beneficial in several embodiments.

[0060] According to several embodiments, the systems and methods described herein are directed towards improved intravascular ultrasound imaging and measurements. In several embodiments, the systems and methods provide vessel-wise distance measurements for a recording of IVUS images within a continuous human vessel using manual translation of a catheter. An IVUS recording that is made while withdrawing the catheter within a vessel is a workflow process that is referred to as a “pullback.” In various embodiments, a reference to “pullback” movement of the catheter may refer to retracting the catheter in a proximal direction and also contemplate advancing the catheter within the vessel in a distal direction. Longitudinal movement comprises pullback or pulling back a catheter from a vessel or other lumen, pushing or otherwise advancing a catheter into a vessel or other lumen, or both. Augmenting a pullback with distance measurement information adds clinical value and workflow efficiently by facilitating length measurement between images in the pullback. In several embodiments, IVUS imaging is used to diagnose unhealthy vasculature and to guide and assess therapies. In various embodiments, IVUS can be used for imaging only. In various embodiments, IVUS can be used for therapy only. In various embodiments IVUS is used for imaging and therapy, with therapies such as heating, coagulation, ablation, ultrasound HIFU, delivery of drugs, anticoagulants (such as heparin, warfarin, dabigatran, apixaban, and / or rivaroxaban), biologics, lytics, thrombolytics, microbubbles, and / or interventional therapies. In one embodiment, the IVUS system includes a disposable catheter used to deploy an ultrasound image acquisition unit within the vasculature and an accompanying imaging system or console. In one embodiment, a processor detects a lengthwise movement of the catheter. The processor may determine a lengthwise position of the catheter using an output device to dictate a lengthwise movement speed to a user and / or using input device to receive the lengthwise movement speed from the user. In some embodiments, the processor may associate IVUS images with the lengthwise position of the catheter at the time the IVUS images were captured. For example, the processor may annotate the IVUS images to include the lengthwise position. The longitudinal position may be defined relative to an anatomical point of interest.

[0061] Advantageously, these systems and methods provide for superior manual control over the position of the catheter while determining an accurate estimate for the lengthwise position of the catheter according to several embodiments. The user manipulation of the IVUS catheter allows for longitudinal measurements and imaging to be conducted relative to a point of interest or location rather than a relative to a point in time. The position- relative measurements and imaging may allow for 3D rendering of a plurality of IVUS images according to various embodiments. In some cases, the systems and methods may employ automated lumen or vessel wall detection and / or a 3D vessel model. The systems and methods provide enhanced imaging quality and increase efficiency by relating the image to an point of interest, which can increase the speed and accuracy for the delivery of one or more therapies, e.g., a stent. In some embodiments, the systems and methods provide for automatically annotating IVUS images with lengthwise position information such as the position, speed, or a length of a lengthwise movement. The embodiments described herein remove the guesswork associated with manually advanced and retrieved and / or retracted IVUS catheters. In turn, physicians can provide patients with more accurate diagnoses and treatments, improving patient outcomes.

[0062] Fig. 1 illustrates an intravascular ultrasound (IVUS) system 100 according to one embodiment. The intravascular ultrasound system 100 includes a catheter body 102. The catheter body 102 is a flexible, elongate member. The catheter body 102 may be a fixed length. In some embodiments, an IVUS catheter has a length configured for connection to a catheter interface module outside of a sterile field. In various embodiments, the catheter body 102 may be at least 90 cm, at least 120 cm, at least 150 cm, at least 180 cm, at least 210 cm, at least 240 cm, at least 270 cm, at least 300 cm, at least 330 cm, or at least 360 cm in length (e.g., 90, 100, 105, 110, 120, 125, 135, 140, 150, 160, 175, 190, 200, 210, 230, 250, 280, 310, 350, 370, or 400 cm in length including values therein). For example, the catheter body 102 may be at least 3 feet (ft), at least 4 ft, at least 5 ft, at least 6 ft, at least 7 ft, at least 8 ft, at least 9 ft, at least 10 ft, at least 11 ft, at least 12 ft, or at least 13 ft in length. In some embodiments, the catheter body 102 may not include any telescoping members. The catheter body 102 may be comprised of one, two, or more housings, lumens, coils, mediums, connectors, sensors, and / or measurement devices. In some embodiments, the catheter body 102 may include one, two, or more material layers to refract ultrasonic signals and / or limit backscatter signals in anintended manner. In one embodiment, one, two, or more material layers may be shaped to refract ultrasonic signals and / or limit backscatter signals in an intended manner, such as with a lens. The catheter body 102 has a proximal end and a distal end.

[0063] The imaging core 104 comprises a transducer that may be a single-element transducer or a multi-element array of transducers in various embodiments. In one embodiment, a single ultrasound transducer (e.g., with only a single element, without multiple elements, without a plurality of elements, and / or without an array of elements) is positioned at an intravascular site with a catheter for acoustic imaging. In various embodiments, a multi- element array may be a 2, 8, 10, 12, 16, 24, 32, 50, 64, 100, 128 element array. In one embodiment, the transducer is rotated by an actuator while the one, two, or more receiving transducers may remain static. The catheter body 102 has a flexible wall extending along the length of the catheter from a proximal end to a distal end. The catheter body 102 also includes one or more lumens, such as a lumen. In one embodiment, the lumen may extend from the proximal end to the distal end of the catheter body 102. In one embodiment, the lumen may extend from a proximal end to a distal portion of the catheter body 102. The lumen may be defined by a wall of the catheter body 102. In one embodiment, the wall of the catheter body is flexible. According to some embodiments, the lumen may be defined by a wall of a member inserted into the catheter body 102. In some embodiments, the catheter body 102 may include two or more lumens. The lumen may be sealable and comprise a proximal port and a distal port.

[0064] In several embodiments, the system 100 includes imaging core 104 with a rotational transducer 105. In various embodiments, the rotational transducer 105 is a component of the imaging core 104. The rotational transducer 105 may be disposed at the distal end of the catheter body 102 and generate a plurality of ultrasonic signals 106. In some embodiments, the rotational transducer 105 may be oriented such that ultrasonic signals propagate perpendicular to the catheter body 102. In some embodiments, the rotational transducer 105 may be oriented such that ultrasonic signals propagate with a circular shape perpendicular to the catheter body 102. In several embodiments, the ultrasound signals propagate away from the perpendicular to the catheter body wall forming a conical shape relative to the catheter wall. The rotational transducer 105 may be oriented such that ultrasonic signals propagate perpendicular to an axis. A device may include an imaging core 104comprising a rotational ultrasound transducer connected to a distal end of a driveshaft. A device may include a flexible elongate member comprising a sealed lumen, wherein the sealed lumen is configured to receive the ultrasound imaging core 104 and an acoustic coupling medium, wherein the sealed lumen comprises a proximal end, a distal end, and a flexible wall extending a length between proximal end and the distal end. The device is configured for connection to a console, wherein the console is configured for rotational actuation of the driveshaft through a lumen of the catheter body 102. The rotational transducer 105 may also detect a plurality of backscatter signals. In some embodiments, the system 100 may include one, two, or more generating transducers and one, two, or more receiving transducers.

[0065] In one embodiment, the lumen is configured to receive rotational transducer 105 and a driveshaft 110. The driveshaft 110 mechanically couples the rotational transducer 105 to a rotational actuator 114. The lumen may be configured to receive a coupling medium. In various embodiments, the system 100 includes an actuator 114. The actuator 114 can comprise a component or system that is configured to cause relative motion (e.g., rotational motion and / or translation motion, rotational motion without translational motion, and / or translational motion without rotation) between two or more components (e.g., a motion between the rotational transducer 105 and the catheter body 102). Actuator 114 can comprise one, two, or more of, or a combination of, e.g., a hub, seal, valve, adhesive, bearing, hinge, pin, ball and pinion, axle, rotational joint, clutch, disc, gear, belt, motor, linear slide, linear actuator, track, groove, slot, cam, vibrational table, etc. In several embodiments, an actuator is not necessarily tied to an electronic, motorized, or otherwise automatic system, and that embodiments of the actuator(s) described herein can be configured to be moved manually, semi-automatically, and / or automatically. For example, the actuator 114 may be a drivetrain or a driveshaft. The actuator 114 may rotate the rotational transducer 105 within the catheter body 102 in an azimuthal direction.

[0066] In one embodiment, images are formed from a plurality of radial ultrasound image lines aligned roughly to a two dimensional (2D) grid in a polar coordinate space orthogonal to the catheter length axis. In this way an annular image is presented to the user that represents a slice of anatomical information at the lengthwise position of acquisition unit. An illustration of such an annular image area with polar coordinate markings and its orientationrelative to catheter body 102 at the position of the acquisition unit is illustrated in Figs.2A and 2B.

[0067] Fig. 2A illustrates the polar plane 202 of a polar coordinate system 200 relative to a catheter body 102. As described above, in some embodiments, the imaging field of an IVUS catheter may be defined as a polar coordinate system 200 centered at one or more transducers 204. As used herein azimuth may refer to an angle 206 (labeled as angle “p” in Fig.2A) between an imaging line 208 and a vertical axis 210 extending from the center. Radius may refer to a distance from the center, i.e. a distance or depth from the one or more transducers. As used herein, axial or longitudinal may refer to an axis perpendicular to the polar coordinate plane and a plurality of imaging lines, which corresponds with movement of the catheter in a proximal / distal direction.

[0068] Fig. 2B illustrates an isometric view of the polar coordinate system shown in Fig. 2A. As shown in Fig. 2B, the polar plane 202 may correspond with a longitudinal position along the catheter body 102 and / or the catheter’s path.

[0069] In various embodiments, images may be formed by a rotating single element or by a multi-element array. During live imaging the acquisition is repeated at an imaging frequency (such as, for example, in the range of 1 – 90 MHz, e.g., 1-10, 10-15, 10-20, 10-25, 10-30, 10-40, 15-30, 15-35, 15-40, 15-50, 15-60, 15-70, 20-30, 30-40, 40-50, 20 -25, 20-30, 20-40, 20-45, 20-50, 25-35, 25-40, 25-45, 25-50, 30-45, 30-50, 40-45, 45-50, 50-60, 50-70, 50-80, 55-75, 55-65, 60-70, 60-90, 70-80, 70-90 MHz and any values and ranges therein). In one embodiment, live imaging the acquisition is repeated at frame rates to provide a real-time 2D imaging modality (such as, for example, frame rates in the range of 12 – 120 Hz, e.g., 12, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 90, 100, 110, 120 Hz) . The pullback recording of sequentially acquired IVUS images made while withdrawing the catheter within a vessel can be used to survey a length of a tissue along the blood vessel. In one embodiment, stacking the 2D images recorded during a pullback a volume of data can be constructed. In one embodiment, by stacking a chosen diameter from each of the annular images, an alternate 2D image referred to as a “strip” image can be formed. In one embodiment, the stacking of data from images acquired during a pullback constitutes spatial sampling of the lengthwise dimension, which is out-of-plane with respect to the individual IVUS images. A pictorial example relating these image types to a stacked image series from pullback is shown in Fig.2C. In one embodiment such a stacked image may not be formed, but knowledge of lengthwise separation of individual images is still attainable and advantageous. In several embodiments, a strip image may be created while the catheter advanced in a distal direction.

[0070] Fig. 2C depicts a strip image 250 comprising a plurality of IVUS images 240 according to one embodiment. IVUS images 240 may be divided into groups or subsets based on the longitudinal position. Groups of IVUS images 240 may be stacked lengthwise to produce a strip image 250. A strip image 250 may be a two-dimensional IVUS image that combines IVUS images 240 in the longitudinal plane. For example, the IVUS images 240 captured between a proximal end of a calcified lesion and a distal end of a calcified lesion may be grouped together to form the strip image 250. In some embodiments, the catheter system may automatically generate strip images for a pullback recording. The processor 112 can automatically generate the strip images based on the time separation of the individual images where the stacking of images is then against a time-axis. When the relative lengthwise position of individual images is known or estimated, such as via embodiments described herein, then individual images may be stacked against a distance-axis representing the nominal longitudinal position or progress of the distal tip of the catheter in the lumen. In some embodiments, the processor 112 may create the strip images aligned to a distance-axis using a relationship between recording time and lengthwise position based on a user input denoting lengthwise progress of the catheter during recording. In some embodiments, the processor 112 may create the strip images aligned to a distance-axis using a relationship between recording time and lengthwise position achieved by pacing the action of the user during pullback. In some embodiments, the processor 112 may create the strip images aligned to a distance-axis using a relationship between recording time and lengthwise position derived from a small encoder at the point of insertion of the catheter to the body.

[0071] In several embodiments, images may be stacked uniformly without distance information. With standard freehand pullback there is no distance information known, so the out-of-plane dimension of a strip image simply represents time or frame-count during the recording. With automated, mechanical sled the movement (e.g., pullback or advancement) progresses at a uniform rate and, lengthwise progress is proportional to recording time (e.g., progress equaling speed multiplied by time), so images can be stacked uniformly against a length-wise axis with a distance scale of millimeters, for instance. In several embodiments,systems for estimating position as a function of recording time are provided herein. In one embodiment, progress as a function of recording time is known so it is possible to create a strip image with a distance scale even if the relationship is not a simple proportionality. In one embodiment, information is advantageous whether a strip image is formed or not. For example, with pullback the real position of images is not necessarily a perfect vertical stack because vessels are tortuous with bends. The lengthwise separation between images of a recording that are proximal and distal to a lesion for instance represents the lesion length whether a strip image is shown or not.

[0072] In one embodiment, longitudinal movements of an IVUS catheter are performed manually to produce IVUS images that are stacked to form a volume or strip image where the lengthwise dimension corresponds to recording time. In one embodiment, no length measurement between frames can be made in this case. In one embodiment, an IVUS device provides for measurements while retracting the IVUS catheter with respect to stationary, external known positions outside the catheter. The addition of lengthwise position information to the movement recording allows the frames to be stacked in distance and length measurement can be made between structures visualized at different times during the longitudinal movement. In one embodiment, lengthwise measurement capability is accomplished using user input based on marks on the catheter body observed by the user while moving the catheter into the patient (e.g., at an introducer sheath, guide catheter, incision point, etc.) at point of insertion. In one embodiment, lengthwise measurement capability is accomplished using synchronized, alignment measurements of the IVUS image data with another imaging modality, such as X- ray fluoroscopy.

[0073] In one embodiment, a manual pullback or advancement without automatic lengthwise position information produces IVUS images that are used for procedure guidance, such as stent placement (e.g., determining where in a vessel stenting will be begin and end). For instance, the start and end points may be determined by the IVUS imaging while manually noting these positions of the IVUS catheter in fluoroscopy (or other imaging modalities). The length between these points could then be estimated based on tracing of the fluoroscopy images. Alternatively, the length between these points may be estimated based on radio- opaque (RO) marker spacing(s) on the IVUS catheter. In various embodiments, a manual pullback or advancement system and method enhance the use of manual lengthwise positionestimation to streamline workflow as well as provide improved visualization of the movement data in a volume or strip display. In various embodiments this is accomplished with efficient clinical workflow without the need for connecting to a motorized automated pull-back device within the patient sterile field, or a telescoping catheter design.

[0074] In some embodiments, one or more markers 302 are spaced along a portion of the length of the catheter body 102. Fig. 3 is a block diagram of a lateral view of the rotational IVUS system 100 with one or more markers 302. In various embodiments, 1 – 40 markers (e.g., 1, 2, 4, 5, 6, 7, 8, 9, 10, 12, 16, 20, 24, 25, 30, 32, 35, 38, 40 markers and any values and ranges therein) are distributed along the catheter body 102. In some embodiments, the markers 302 are evenly spaced longitudinally along the catheter body 102. For example, the markers 302 may be spaced 0.5 – 6.0 cm (e.g., 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.5, 1.8, 2.0, 2.3, 2.5, 2.7, 3.0, 3.3, 3.5, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.4, 4.5, 4.8, 5.0, 5.3, 5.5., 5.8, 6.0 cm apart and any values and ranges therein). In one embodiment, the markers 302 is radiopaque (RO).

[0075] In various embodiments the markers 302 are disposed on an external surface of the catheter body 102. The markers 302 may be printed or swaged rings disposed on or embedded in the external surface of the catheter body 102. Alternatively the markers may be inserted inside the catheter body on an interior components such as another tubular component with swaged or fused RO rings. In one embodiment, the markers 302 are radiopaque ring members disposed within or upon the catheter body 102. In some embodiments, the marker 302 may be major marker or a minor marker. Major markers may indicate a longitudinal distance such as 2 - 10 cm (e.g., 2, 3, 5, 7, 8, 10 cm and any values and ranges therein), while minor markers may be disposed between major markers and positioned at a particular fraction of the distance between the two major markers. In some embodiments, the marker 302 may be major marker or a minor marker. Major markers may indicate a longitudinal distance such as 20.5 - 10 cm (e.g., 0.5, 1, 2, 3, 5, 7, 8, 10 cm and any values and ranges therein), while minor markers may be disposed between major markers and positioned at a particular fraction of the distance between the two major markers. For example, the minor markers may be disposed at everyth rd1 / 4 , 1 / 3 , or ½ of the longitudinal distance between two major markers. In some embodiments, the major and minor marker have different longitudinal lengths suchthat major markers may be distinguished from minor markers in an image, such as an X-ray image (e.g., radiography, fluoroscopy, and / or angiography image).

[0076] In one embodiment, a manual movement IVUS image series capture is recorded while manually translating the catheter along a vessel length. The lengthwise position of the images in the series are estimated by a user / system interaction. This interaction will leverage visible bands or markers on the IVUS catheter that indicate longitudinal translation past one or more surrounding anatomical references. For example, the progress of the translating catheter can be judged by the movement of radiopaque (RO) markers past bony fiducials visible in fluoroscopy or by visible catheter markings past the entry point to the body. In one embodiment, the interaction is a system-to-operator type, such as using audible pacing clicks to pace the operator’s movement of the catheter. In one embodiment, the interaction is an operator-to-system type, such as voice entered waypoint indicators given by the operator to the system. By correlating the capture time and physical catheter translation, an image series may be rendered against a length axis in the direction of longitudinal motion (such as in the case of a “strip” image). In one embodiment, an image series is rendered against lengthwise position, vessel-wise lengths, e.g., distances between images, such as may correspond to desired stent start and end positions in the series can be obtained and documented through the IVUS system user interface. Lengthwise distances between anatomical points of interest can be obtained and utilized with the IVUS images to aid clinical therapy decisions such as selected balloon lengths for percutaneous transluminal angioplasty and expandable stent lengths. In one embodiment, such lengthwise distances between images in the series are obtained whether the image series has been rendered against lengthwise positions or not.

[0077] In some embodiments, the IVUS catheter system may include an output device 304 to, for example, help a user receive pacing and / or measurement information. The output device 304 may be an audio output device, a haptic output device, a display device, or a combination thereof. An audio output device may be one or more speakers, headphones, or ear pieces configured to emit a sound, tone, click, word, or phrase. A haptic output device is configured to apply a force to a user, generate a vibration, generate a movement, or a combination thereof. For example, a vibration on a watch or other display device, a visual cue and / or sound may be used to signal catheter movement in a vessel or other measurements. A display device may be any device suitable for providing a visual, sound, haptic or other output,such as a television, a monitor, a mobile device, a tablet, a smart watch, projector screen, visor display, eyepiece, or the like.

[0078] The output device 304 may provide an output from the system to an operator / user, such as a notification, indication, instructions, and / or feedback to the operator / user. In some embodiments, the processor 112 may generate an output and instruct the output device 304 to provide the output to the user. As discussed in greater detail below, the processor 112 may instruct the output device to provide a pacing instruction or pacing notification to a user. For example, at the instruction of the processor 112, the output device 304 may provide an audio instruction or notification in response to a longitudinal movement of the catheter body 102.

[0079] In some embodiments, the IVUS catheter system may include an input device 306 for the operator / user to communicate with the system. The input device 306 may include one or more of a microphone, a tactile input device. A tactile input device may be a keyboard, a button, a switch, a pedal etc. The input device 306 may receive an input from a user, such as a voice-input. In some embodiments, the processor 112 may be placed in electronic communication with the input device 306 and configured to receive inputs from the input device 306. For example, as discussed below, the processor 112 may receive a pacing input from a user via the input device 306.

[0080] According to some embodiments, the catheter system 100 may not include a motorized pullback device. Instead, the catheter body 102 may be moved manually in a longitudinal direction by a user, such as a physician.

[0081] In various embodiments, a system-to-operator interaction involves the processor outputting information to a user. Fig. 4A depicts a system-to-operator interaction process 320 for detection of a manual longitudinal movement of an IVUS catheter according to one embodiment. The system-to-operator interaction process 320 may be performed by processor, such as the processor 112. As discussed above, the processor 112 may control the elements of an intravascular ultrasound catheter system, such as the output device 304 to communicate to the user and the input device 306 for the user to communicate with the system. The process 320 shown in Fig. 4A is an example system-to-operator interaction process. In some embodiments, the process 320 may include more or fewer steps. In some embodiments,one or more of the steps of process 320 may be performed in a different order or simultaneously with respect to one or more of the other steps of process 320.

[0082] The system-to-operator interaction process 320 may begin at step 322 when an IVUS procedure begins collecting IVUS images according to one embodiment. In some embodiments, the IVUS procedure may begin when an IVUS catheter is inserted into a patient. The IVUS catheter may be inserted and manually advanced into (or retracted from) a vessel. For example, physician conducting the procedure may insert the IVUS catheter into a femoral artery of a patient and manually advance the catheter through the patient’s vasculature.

[0083] The system-to-operator interaction process 320 may move to step 324 where the processor 112 outputs information about a longitudinal movement of the catheter to a user. In some embodiments, the processor 112 may receive an indication from the user for the system to begin to provide output information.

[0084] The processor 112 may provide a pacing instruction to the user via an output device, such as the output device 304. The output device may be an audio output device, a haptic output device, a display device, or a combination thereof. The pacing instruction may include a plurality of evenly spaced outputs that indicate the recommended speed of the catheter.

[0085] As discussed above, the catheter body may include one or more markers, such as the markers 302. The marker(s) may be evenly spaced longitudinally along the catheter body. The one or more markers may be radiopaque.

[0086] The system-to-operator interaction output may include a plurality of pacing instructions from the process to the user that dictates a pace at which the user should move the catheter such that the sequential markers of the one or more markers align with the starting anatomical point. For example, a series of sounds, such as beeps, may be played by the system as a pacing output for the user to listen to. The beeps may be played with a steady tempo to dictate to the user the processor’s recommended longitudinal movement speed. At a first beep, a first marker of the one or more markers should be aligned with the starting point. In some embodiments, an X-ray image (e.g., radioscopy, fluoroscopy, angiography) is taken of a portion of the patient, and the position of one or more radiopaque markers relative to the starting point may be assessed. The catheter may be moved by the user in a proximal or distal direction, and via the pacing output provided by the system at a second beep, indicating that asecond marker of the one or more markers should be aligned with the starting point. This sequence may continue such that sequential markers of the one or more markers are aligned with the starting point upon each subsequent beep, e.g. a third marker may be aligned at a third beep, a fourth marker may be aligned at a fourth beep, and so on.

[0087] In some embodiments, the rate at which the one or more markers align with the starting point may correspond with the recommended longitudinal movement speed of the catheter. In some embodiments, the recommended longitudinal movement speed may be 0.5 – 20 mm / s, e.g., 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 mm / s and values and ranges therein. The recommended longitudinal speed may be a preprogrammed value. In some embodiments, the processor 112 may prompt the user to enter the recommended longitudinal speed and receive the longitudinal speed from the user, and can provide audible feedback such as an alarm, and / or request to speed up or slow down. In some embodiments, the processor 112 may receive another indication from the user to end the movement dictation. Similarly, the indication to end the movement direction may be received from the input device 306.

[0088] In some embodiments, the process 320 may move to step 326 where the processor 112 may detect or measure a length of the longitudinal movement. The processor 112 may detect the length of the movement based on the number of outputs provided by the processor 112. The number of outputs may correspond with a number of marker lengths moved in the proximal / distal direction. For example, the processor 112 can provide four outputs which may be provided to a user during the system outputting pacing information to the user, which may correspond with the catheter moving three marker distances in the proximal / distal direction, which are known distances. The four markers may be spaced 1 cm apart. Thus, the processor 112 may determine the proximal / distal movement to be 3 cm.

[0089] The process 320 may move to step 328 where the processor 112 may provide an output to the user. The processor 112 may provide the output based on the length of the longitudinal movement. The output may indicate a distance or a speed of the catheter movement.

[0090] In some embodiments, the system-to-operator interaction output may include an annotated IVUS image. During a movement of the catheter body, the IVUS catheter system may capture one or more IVUS images. The processor 112 may calculate a movementof the catheter body and annotate the IVUS images to indicate a longitudinal position of the catheter. The longitudinal position may be a position of the distal tip of the catheter relative to a point of insertion or to the starting anatomical point. In some embodiments, the processor 112 may annotate the IVUS image to include a corresponding longitudinal position of the catheter at the time the image is captured. Annotations may be provided in real-time or added retrospectively. According to some embodiments, the processor 112 may annotate the IVUS image to include a speed of the catheter.

[0091] According to some embodiments, the IVUS images may be divided into groups or subsets based on the longitudinal position. Groups of IVUS images may be stacked lengthwise to produce a strip image. A strip image may be a two-dimensional IVUS image that combines IVUS images in the longitudinal plane as shown in Fig. 2C. For example, the IVUS images captured between a proximal end of a calcified lesion and a distal end of a calcified lesion may be grouped together to form a strip image. In some embodiments, the catheter system may automatically generate strip images. The processor 112 may automatically generate the strip images based on the longitudinal position of the distal tip of the catheter. In some embodiments, the processor 112 may create the strip images based on a user input, such as the indication to start a movement dictation. In some embodiments, the processor 112 may calculate the length of the strip image and provide it to a user.

[0092] In some embodiments, the processor 112 may detect an error condition during a procedure. The processor 112 may generate an output indicating the error condition. The error condition may be detected when markers are not detected, repeated, or detected out of order. An error condition may exist if markers are detected in a sufficiently non-uniform manner. In some embodiments, where an error condition exist, the processor 112 may reject the longitudinal movement length, the longitudinal movement speed, and / or the longitudinal position of the catheter. The system may retain the recorded images and fall back to a recording without lengthwise measurement capability in the case such an error is detected. The processor 112 may provide the error condition to a user via the output. In some embodiments, the output may include IVUS images associated with the error condition, the rejected longitudinal movement length, the rejected longitudinal movement speed, and / or the rejected longitudinal position of the catheter along with the error condition.

[0093] Although the process 320 is described as detecting a manual longitudinal movement of the catheter via a system-to-operator interaction, the process 320 may be implemented with an automatic longitudinal actuator. The automatic longitudinal actuator may cause a longitudinal movement of the catheter relative to a patient’s vessel. In some embodiments, the process 320 may also employ a mechanical pullback sled, co-registration, or an encoder measuring translation. In one embodiment, no motor and / or no-co-registration is used. In one embodiment, no encoder is used. In one embodiment, no actuation lever, knob, or tool is used.

[0094] Fig.4B shows a system-to-operator interaction process 400 for detection of a manual longitudinal movement of an IVUS catheter according to one embodiment. In some embodiments, the process 400 may include more or fewer steps. In some embodiments, one or more of the steps of process 400 may be performed in a different order or simultaneously with respect to one or more of the other steps of process 400. In a system-to-operator interaction embodiment, an operator performing a longitudinal movement may be paced by a series of indications from the system representing an intended uniform progress of the observable markings on the catheter past a fixed point. In the system-to-operator embodiment the system guidance can be thought of as guiding longitudinal speed, similar to how a metronome guides the pace of a beat for a musician playing music. A target longitudinal movement rate is programmed in the system (or selected from pre-configured values), e.g., 1-20 mm / sec (e.g., 1, 2, 5, 10, 12, 15, 20 mm / sec and values and ranges therein), and the system provides pacing indicators while the operator performs the movement (e.g., pullback or a push-forward) so that the operator may adapt the translation rate as well as judge the intended rate was achieved. In this embodiment the mapping between image capture time and longitudinal position can be aligned and / or synchronized according to the intended translation rate. In one embodiment, the user may reject a spatial alignment or synchronization and re-attempt the process.

[0095] The system-to-operator interaction process 400 may begin with step 402 where processor of a IVUS catheter system, such as the processor 112, may start an image series recording. Next, the process 400 may move to step 404 where the processor 112 may pace progress with outputs for each unit of distance progress via pace progression of the catheter by a system pulse. Similar to steps 324, 326, and 328 described above, the processor 112 may output a longitudinal movement of the catheter using one or more pacing instructionsto the user. In various embodiments, the processor 112 may provide a pacing instruction to a user via an output device. For example, the processor 112 may generate a series of vibrations via a haptic output device that dictate a recommended longitudinal speed to a user. In another example, the processor 112 may generate a series of beeps or chimes via a set of speakers that dictate a recommended longitudinal speed to a user. The processor 112 may determine a longitudinal position of the catheter based on a number of pacing instructions provided during a movement dictation. In some embodiments, the processor 112 may associate IVUS image(s) with the longitudinal position of the catheter at the time the IVUS image(s) were captured. For example, the processor 112 may annotate the IVUS images to include the longitudinal position.

[0096] The process 400 may move to step 406 where the recording of IVUS images is ended. In some embodiments, an IVUS catheter system may receive an input from a user to cease recording IVUS images. Next, the process 400 may move to step 408 where the processor may prompt a user to accept or reject the longitudinal position data. As discussed above, the processor 112 may provide the annotated IVUS images to a user as an output. The processor 112 may also provide a user interface, such as a software interface, that allows a user to review the annotated IVUS images and accept or reject the annotated longitudinal position data. In one embodiment, the review process may include a dialog to present the recorded progress information as annotations of distance progress for instance on a strip image or timeline with or without key images associated with the dictations. Images may be shown as thumbnails with a dialog asking to the operator if the waypoint data appears correct and explaining that lengthwise distance between images of the series will be interpolated based on this data.

[0097] In various embodiments, an operator-to-system interaction involves the user inputting information to the system. Fig.5A depicts an operator-to-system interaction process 500 for detection of a manual longitudinal movement of an IVUS catheter according to one embodiment. In some embodiments, the operator-to-system interaction process 500 may include more or fewer steps. In some embodiments, one or more of the steps of process 500 may be performed in a different order or simultaneously with respect to one or more of the other steps of process 500.

[0098] In various embodiments, the input may be received through a user interface and / or via the input device 306. For example, the user may provide a keyboard, mouse, touch- screen, or other input to initiate a movement dictation. In some embodiments, the indicationmay be a speech input, which the processor 112 may receive via the input device 306. In some embodiments, the indication to start the movement dictation may include an anatomical point which may be a starting point or a reference point. Anatomical points may include an anatomical structure such as an anastomosis, a point relative to a radiopaque structure, a proximal end of a calcified lesion, a distal end of the calcified lesion, etc. As discussed below in conjunction with Fig. 5A and 5B, the user may dictate or enter one or more anatomical points to the IVUS catheter system.

[0099] The operator-to-system interaction process 500 may begin with step 502 where an IVUS procedure begins according to one embodiment. Similar to step 322, an IVUS procedure may begin when an IVUS catheter begins collecting IVUS images. In some embodiments, the IVUS procedure may begin when an IVUS catheter is inserted into a patient. The IVUS catheter may be inserted and manually advanced into (or retracted from) a vessel. For example, physician conducting the procedure may insert the IVUS catheter into a femoral artery of a patient and manually advance the catheter through the patient’s vasculature.

[0100] The operator-to-system interaction process 500 may move to step 504 where the processor 112 may receive a user input. The catheter system may include an input device. The input device may be a microphone, a tactile input device, or a camera. The processor 112 may receive an input from a user, such as a voice-input, via the input device. In some embodiments, the input may be words or sounds indicating a longitudinal movement speed. For example, the input device may be a microphone. The user may provide input indicating the longitudinal speed, and the processor 112 may receive the information and calculate a longitudinal speed.

[0101] In some embodiments, the user input may provide a reference point input. A reference point input may associate a current longitudinal position relative to an anatomical point such as a radiopaque structure, a proximal end of a calcified lesion, a distal end of a calcified lesion, or any point where the catheter may be positioned. For example, the input device may be a microphone, and a physician may provide a marker input indicating that a first marker of the one or more markers is aligned with an anatomical point, such as a boney fiducial. At the same time, the distal tip of the catheter may be positioned at a distal end of a calcified lesion. For example, the physician may say “one,” and the processor 112 may receive the speech input via the input device 306.

[0102] The user may begin to move the catheter in the proximal / distal direction. According to some embodiments, the user may provide one or more pacing inputs indicating that subsequent markers are disposed at the reference point, and the processor 112 may receive the pacing input(s). The one or more pacing inputs may be entered through the input device 306 and may be touch inputs, speech inputs, mechanical inputs, etc. Based on the pacing inputs, the processor 112 may calculate a longitudinal movement distance based on the one or more pacing inputs and the known distance between the one or more markers.

[0103] Returning to the example above, the user (e.g., operator, physician, medical personnel) may move the catheter in a proximal direction (e.g., perform a pullback maneuver) or a distal direction (e.g., advance the catheter) after providing the reference point. At the beginning of the longitudinal movement, a first marker of the one or more markers may be aligned with a boney fiducial point. As the physician pulls the catheter in the proximal direction, the physician may provide a second input, such as saying “two” when a second adjacent marker is aligned with the boney fiducial point, which may be received by the processor 112 via the input device 306. The movement may continue, and the physician may provide subsequent user provided inputs indicating when a third, fourth, fifth, . . . nth marker are aligned with the boney fiducial. Based on the user’s provided inputs, the processor 112 may calculate a position and / or longitudinal speed of the catheter and imaging core during the longitudinal movement.

[0104] Next, the process 500 may move to step 508 where the processor 112 may provide an output to the user. Step 508 may be substantially similar to step 328. The output may be audio, haptic, visual, or a combination thereof. The output may indicate a longitudinal position of the catheter and / or a speed of the longitudinal movement. In some embodiments, the output may include IVUS image(s) and / or a strip image. The IVUS image(s) and the strip image may include an annotation indicating the longitudinal position of the catheter.

[0105] Fig. 5B shows an operator-to-system interaction process 600 for detection of a manual longitudinal movement of an IVUS catheter according to one embodiment. The operator-to-system interaction process 600 shown in Fig. 5B is an example process. In some embodiments, the operator-to-system interaction process 600 may include more or fewer steps. In some embodiments, one or more of the steps of process 600 may be performed in a different order or simultaneously with respect to one or more of the other steps of process 600. In oneembodiment of an operator-to-system interaction, the operator would provide input to the system regarding manual catheter translation progress during acquisition of the imaging series. For instance, a user may count aloud the catheter markers as they pass by a bony fiducial seen in fluoroscopy, e.g., “Start, One, Two, Three,” etc. with the audible input to a microphone. In this embodiment the spatial distance mapping between image capture time and longitudinal position would be an interpolated function based on the operator inputs. In one embodiment, the system may detect error conditions and reject the spatial measurement calculation. For instance, if missed repeated or out of order counts are detected or if severely non-uniform counts are detected, the system can reject spatial measurement and inform the user so they may repeat the action if desired. In one embodiment, translation progress indicators could be voice- command such as in the above example embodiment or another input interface mechanism such as a tactile user input device, e.g., buttons on a user-input device like a display screen, button, or foot switch. The ability to audibly indicate translation progress by unique counts / commands, such as spoken “Start, One, Two, Three,” etc. commands rather than a non- specific command likely improve accuracy and robustness. In one embodiment, non-specific progress indicators, such as spoken “Mark, Mark, Mark” indications, or footswitch taps, taps on the catheter body if for instance a haptic sensor is provided, etc. would be sufficient.

[0106] The operator-to-system interaction process 600 may begin at step 602 where processor of a IVUS catheter system, such as the processor 112, start an image series recording according to one embodiment. Next, the process 600 may proceed to step 604 where the processor 112 marks each of unit of distance progress based on the input provided by the user.

[0107] In some embodiments, step 604 may include the processor may receive one or more pacing inputs from a user / operator as described above. Similar to steps 324, 326, and 328 described above, the processor 112 may determine a longitudinal position of the catheter based on the one or more pacing inputs. In some embodiments, the processor 112 may associate IVUS image(s) with the longitudinal position of the catheter at the time the IVUS image(s) were captured. For example, the processor 112 may annotate the IVUS images to include the longitudinal position.

[0108] The process 600 may move to step 606 where the recording of IVUS images is ended. In some embodiments, an IVUS catheter system may receive an input from a user to cease recording IVUS images. Next, the process 600 may move to step 608 where the processormay prompt a user to accept or reject the longitudinal waypoint position data. As discussed above, the processor 112 may provide the annotated IVUS images to a user as an output. The processor 112 may also provide a user interface, such as a software interface, that allows a user to review the annotated IVUS images and accept or reject the annotated longitudinal position data.

[0109] In several embodiments, it is advantageous to use a complementary imaging modality such as fluoroscopy or a series of radiographic images to gauge progress of the IVUS catheter past an anatomical reference that is close to the vascular anatomy of interest, such as a bony fiducial near a lesion of interest. Figs. 6A-D illustrate reference X-ray images of an IVUS catheter with a series of equally spaced radio-opaque markers may look at the point that each marker crosses a fiducial reference. By providing knowledge that key frames of an IVUS strip image are separated by known lengthwise distance, interpolation can be used to infer the spacing of the entire image series. The strip image, for instance, can then be reconstructed against a distance-based lengthwise axis rather than time. In one embodiment, lengthwise distances between frames of the IVUS series, such as the intended start and end points for stent placement, may be conveniently estimated and documented. In one embodiment, insertion depth determined by visual indicators (insertion depth markings) on the catheter body progressing past a fixed reference, such as the catheter introducer sheath may be used.

[0110] Fig. 6A is an X-ray image demonstrating the positioning of a plurality of markers 1002 relative to a fiducial point 1004. As discussed above, an IVUS catheter system may include one or more markers 1002. The markers 1002 may be disposed longitudinally along the catheter body 1006. In some embodiments, such as the embodiments shown in Figs. 6A-6D, the one or more markers may be radiopaque. The fiducial point 1004 may be any anatomical point as described above. For example, the catheter body 1006 may be inserted into a patient’s leg in an inferior direction such that the catheter passes the knee, and the fiducial point 1004 may be an intercondylar fossa.

[0111] According to some embodiments, the one or more markers 1002 may be used to determine a position of the catheter body 1006 relative to the fiducial point. For example, the longitudinal position of the catheter body 1006 and the transducer(s) disposed therein may be determined during a longitudinal movement of the catheter, e.g., a longitudinal movement of the catheter body 1006 in a proximal direction. In some embodiments, themarkers 1002 may be evenly spaced longitudinally along the catheter body 1006, allowing a user to determine the distance the catheter body 1006 has traveled longitudinally relative to a fiducial point 1004. This process is shown in Figs. 6A – 6D and can be implemented in the system-to-operator embodiments and the operator-to-system embodiments described above.

[0112] As shown in Fig. 6A, a first marker of the markers 1002 has reached the fiducial point 1004. The catheter body 1006 may be pulled back 1 marker distance, i.e. a distance corresponding to the space between two markers. As shown in Fig. 6B, after the catheter body 1006 has been moved 1 marker distance in the proximal direction, a user may confirm the distance by confirming that a second marker of the markers 1002 is now in line with the fiducial point 1004 and the first marker of the markers 1002 has moved past the fiducial point in a proximal direction. This process may be repeated as the catheter body 1006 is moved longitudinally during a procedure. For example, the catheter body 1006 may continue to be moved in a proximal direction during a longitudinal movement such that more markers 1002 pass the fiducial point 1004. In Fig. 6C, two markers of the markers 1002 have passed the fiducial point 1004, and in Fig. 6D, three markers of the markers 1002 have passed the fiducial point 1004. Use of Encoders In Some Embodiments

[0113] In several embodiments, the manual movement measuring device and methods involve an IVUS image series capture recording while manually retracting or inserting a catheter along the vessel while relative or absolute insertion depth of the catheter is measured and recorded by means for measuring, such as an axial translation position measuring device (e.g., an encoder, position sensor, alignment device, etc.) at or near the location of catheter insertion to the patient’s body. In one embodiment, spatial position of the images along the vessel length in the series will be estimated using the insertion depth data. With this data, an image series may be rendered against a length axis. With this spatial alignment, a strip image may be created and displayed. In one embodiment, the image series may be rendered and displayed against a longitudinal length axis, longitudinal lengths, or distances between relevant positions in the series. Distances between anatomical points of interest can be obtained with sufficient accuracy and detailed IVUS images aiding clinical therapy decisions such as preferred balloon lengths for percutaneous transluminal angioplastyand / or expandable stent lengths. In various embodiments, a method of measuring a lengthwise distance between a series of images captured while an intravascular ultrasound (IVUS) catheter is moved by hand can include moving the IVUS catheter along a longitudinal axis of the IVUS catheter with a hand, capturing a plurality of images with the IVUS catheter while moving the IVUS catheter in a proximal direction or a distal direction along the longitudinal axis of the IVUS catheter, measuring a distance travelled by the IVUS catheter with means for encoding, associating an image or tissue feature in the plurality of images with the distance travelled by the IVUS catheter, and determining a longitudinal length between images or of the tissue feature based on the distance measured by the means for encoding. Means for encoding for including can comprise or consist essentially of, for example, an encoder not associated with a mechanical actuator or motor. In various embodiments the means for encoding is mechanical, optical, inductive, and / or capacitive (or combinations thereof). Such methods can avoid capturing fluoroscopy images or images from alternative imaging modalities reducing x-ray exposure and simplifying the measurement process.

[0114] Measurement of an axial translation catheter position from outside the patient’s body may be slightly different than measurements of the position of catheter tip containing the imaging core. Relative movement along the bends and curves of the intervening vasculature, the non-rigid nature of body tissue, and / or blood pressure pulsing through can introduce a lag between measurements at the catheter tip compared to the measurements outside the patient’s body. Inferring translation distance at the catheter tip based on relative or absolute catheter insertion depth (measured exterior to the body, or at the point of insertion) relies on stability of the catheter path or “track” within the vasculature of the body. Differences in measurements between tip translation and insertion depth can be characterized as a simple lag that can be accounted for by disregarding an initial period of imaging while “slack” is taken out.

[0115] Fig. 7 illustrates a lag in translation between translation at a catheter point of insertion into the patient compared to translation at the catheter tip. In one embodiment, an initial portion of an IVUS strip image (e.g., a first and second IVUS image)may be disregarded or adjusted to account for the lag introduced by taking up slack, or stabilizing stresses in the catheter-vascular path system. Such an exclusion period or adjustment may be calibrated a priori for a clinical scenario. Such an exclusion period or adjustment may be informed bysoftware analysis of strip images. In several embodiments, software may be used to detect disqualifying circumstances to improve reliability. Checks on the longitudinal movement of the catheter, such as rate and continuity of the longitudinal movement, by the system may be beneficial. For instance, irregularities in the longitudinal motion measured at the point of insertion may indicate an unfavorable relationship between tip motion and insertion point motion. In one embodiment, software analysis of the image, such as estimating frame to frame difference may be used to monitor a quality of the longitudinal movement and the associated strip image. For instance, periods of time with significantly more stationary images may indicate an unfavorable relationship between tip motion and insertion point motion. In one embodiment, software may provide automated workflow to notify the user if spatial alignment measurement is rejected due to internal quality checks, and suggests the user re-try the measurement. Additional algorithms within the system software may be utilized to improve spatial alignment measurements beyond solely using the insertion depth data.

[0116] In several embodiments, image data may be used to improve measurement performance by analyzing images during manual, longitudinal movement of the catheter. Image difference magnitudes, speckle decorrelation rate, optical flow, or similarity searching among sub-regions may be useful in augmenting the estimate of motion provided by the encoder. Images from an alternate modality, such as fluoroscopy may be used to improve performance, for instance by identifying features of the IVUS catheter within the body as the manual longitudinal movement of the catheter proceeds. Methods to improve performance may augment motion estimation throughout the movement, or perhaps just to account for lag.

[0117] In various embodiments, the insertion depth encoding device may be in wireless communication with a separate imaging system or connected by wire. The insertion depth encoding device may be integrated within a catheter introducer sheath, a guiding catheter, or a separate device. The insertion depth encoding device may be attached to a catheter introducer sheath, guiding catheter, or affixed separately near to the point of insertion of the catheter to the body. The insertion depth encoding device may produce absolute or relative insertion depth data.

[0118] In one embodiment, the encoder device is continuously active (e.g., not just active during capture of an image series). With continuously active longitudinal translation information (e.g., direction, additional feedback, such as overall insertion depth) may beprovided to user with information that may also be useful to adjust imaging settings during phases of the procedure. In one example, a deeper penetration setting may be useful while moving the catheter in one direction and a higher resolution the other.

[0119] Fig. 8 illustrates an embodiment of a relative insertion depth measurement device using a longitudinal translation mechanical encoder affixed near to the point of catheter insertion into a patient’s body. In one embodiment, the relative insertion depth measurement device is a mechanical encoder module 1100. The catheter 1105 may be passed through the encoder module 1100, or the encoder module 1100 may be positioned in contact (e.g., partial or complete engagement around a circumference) with the catheter 1105.

[0120] In various embodiments, the encoder module 1100 may include (i) a small device disposed at the point of insertion of the catheter to the body, (ii) the device may be handheld, for instance if clinical practice accommodates holding the introducer sheath as the catheter is inserted or pulled back to create an IVUS image recording, the displacement encoder may be held by the hand against the introducer to simultaneously stabilize the point of insertion while longitudinal translation measurements are made, (iii) relative insertion depth measurements are made by the device which are recorded synchronously with the image capture, (iv) optionally including or excluding special markings or design features are needed on the catheter body, (v) the device may be disposable, (vi) the device may be re-sterilizable for frequent re-use, and / or (vii) one or more encoder technologies could be used to sense the motion of the catheter. In some embodiments, the catheter body may not include any telescoping members, such as telescoping members with an inner member disposed within a lumen of an outer sheath to facilitate movement of the inner member axially within the outer sheath. In some embodiments, the catheter body may not include a tracking guide, or sled used to move the imaging unit.

[0121] In several embodiments, a relative insertion depth measurement device uses a longitudinal translation inductive encoder. In one embodiment, a Linear Variable Differential Transformer (LVDT) module 1200 may be used to measure the linear translation of the catheter as shown in Figs. 9A and 9B. The LVDT module 1200 may include a longitudinal translation sensor for measuring IVUS movements in a longitudinal direction. In one embodiment, the catheter 1205 may be manually moved (e.g., axial translation) by hand. In several embodiments the LVDT module 1200 may include (i) an outer housing 1210 withprimary and / or secondary windings around the catheter 1205, (ii) outer housing 1210 that may be held stationary while the catheter 1205 is longitudinally translated, and / or (iii) a core 1220 that may be attached to the catheter 1205. In one embodiment, the outer housing 1210 may be affixed to a sheath outside the patient’s body. In one embodiment, the core 1220 can be a torque coil and / or a Ferrite core affixed to the catheter 1205 via a clam shell latching. In one embodiment, the outer housing 1210 may include a primary excitation winding 1212, a secondary left winding 1214, a secondary right winding 1216, and / or a communication component 1218 configured to communicate data with the relative insertion depth measurement device. The communication component 1218 may be wired or wireless (e.g., Bluetooth). Fig. 9C illustrates a schematic circuit diagram of the LVDT module 1200 operation.

[0122] Fig. 10 depicts a schematic diagram of coupled inductors according to one embodiment. In several embodiments, a relative insertion depth measurement device may employ one, two or more longitudinal translation inductive encoders. In one embodiment, one or more coupled inductors 1302, 1304 may be used. In one embodiment, coupled inductor coils may include a primary excitation coil and a secondary receive coil. The catheter torque coil may be a ferrous or Ferrite material. As the torque coil is translated through a first, proximal / primary inductor winding coil and a secondary, distal inductor winding coil, this may cause a phase shift in the signal received in the secondary winding. The phase shift may be measured to sense length or movement. A first inductor (coil) 1302 may be located at the proximal end of the catheter body 1304 and a second inductor (coil) 1306 may be located near the catheter entry into the sheath. Both the first inductor 1302 and second inductor 1306 may be disposed external to the catheter body 1304 and the catheter can be retracted (pulled) or inserted (pushed) through the distal coil 1306. The proximal coil 1302 may be in a fixed position relative to the catheter at the proximal end and can be excited with a narrow band alternating electrical current at a frequency in a range of 1 kHz – 100 MHz (e.g., 1, 2, 5, 10, 15, 20, 25, 50, 100, 200, 300, 400, 500 kHz, 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 MHz, and any values and ranges therein). The alternating electrical current of the proximal coil 1302 may generate a magnetic field that can be coupled to the distal coil 1306 through a ferrous (e.g., stainless steel) cable tube of the imaging core in the catheter body 1304. The distal coil 1306 may be the receiving coil. The phase difference between the excitation signal at theproximal coil 1302 and receive signal captured by the distal coil 1306 may correspond to the magnetic field propagation through the length of the cable tube between the proximal and distal coils (1302 and 1306, respectively). Changing the length of the section of cable tube between the proximal coil 1302 and distal coil 1306 during pullback changes the relative phase, which can be used to determine the change in length. Phase may be determined by precise time measurements of the receive signal relative to the excitation signal, or complex demodulation of the receive signal using a complex demodulation signal frequency locked to the excitation signal, or by other means to measure the relative phase.

[0123] In several embodiments, a relative insertion depth measurement device may employ a longitudinal translation optical encoder. In one embodiment, the relative insertion depth measurement device may be a longitudinal translation optical encoder module. In various embodiments, optical measurement may include (i) use surface irregularities or texture and cross-correlation processing between successive images, (ii) utilize printed pattern on the catheter such as visual marking, QR coding, handwriting capture systems, or custom markings on the catheter and integration with an introducer sheath, guiding catheter, etc. Laser technology may also be similarly used. In one embodiment, an optical encoder 1400 may measure changes in position by optically acquiring sequential surface images or frames and mathematically determining the direction and magnitude of movement as shown in Fig.11. In one embodiment, the optical encoder 1400 can include a light source 1410 (e.g., an LED), a lens 1412 (e.g., a light pipe), and an optical sensor 1420 (e.g., image sensor, light sensor) in a housing 1402 that optically acquires surface images from a catheter 1405. In one embodiment, an optical encoder may be standalone battery powered and optionally include Bluetooth wireless (no cables) for improved ease of use.

[0124] Fig.12 illustrates an embodiment of a relative insertion depth measurement device using an axial translation mechanical encoder affixed near to the point of catheter insertion in to a patient’s body. In one embodiment, the relative insertion depth measurement device is a mechanical encoder module 1100. The catheter 1105 may be passed through the encoder module 1100, or the encoder module 1100 may be positioned in contact (e.g., partial or complete engagement around a circumference) with the catheter 1105. In one embodiment, a wheel 1130 partially engages the catheter 1105 by riding on the catheter body, with a mechanism 1120 such as a hinged arm with spring loaded pressure to engage the wheel 1130with friction pressure to measure movement of the catheter 1105. An encoder 1110 is positioned at an axle of the wheel 1130 and provides direction and pullback distance information to the system. In one embodiment, information is transmitted via Bluetooth. In various embodiments, the encoder module 1100 may include (i) a small device disposed at the point of insertion of the catheter to the body, (ii) the device may be handheld, for instance if clinical practice accommodates holding the introducer sheath as the catheter is pulled back to create an IVUS image recording, the displacement encoder may be held by the hand against the introducer to simultaneously stabilize the point of insertion while translation measurements are made, (iii) relative insertion depth measurements are made by the device which are recorded synchronously with the image capture, (iv) optionally including or excluding special markings or design features are needed on the catheter body, and / or (v) one or more encoder technologies could be used to sense the motion of the wheel axle such as a quadrature optical beam-break sensor and a fenestrated wheel, etc. In some embodiments, the catheter body may not include any telescoping members, such as telescoping members with an inner member disposed within a lumen of an outer sheath to facilitate movement of the inner member axially within the outer sheath. In some embodiments, the catheter body may not include a tracking guide, or sled used to move the imaging unit.

[0125] Although disclosure is provided on systems with and without encoders, features of the non-encoder embodiments described herein may be used with encoder embodiments, and vice versa.

[0126] In several embodiments, an impedance-based system may be used to determine a location of the IVUS catheter within the patient. The position of the IVUS catheter may be based on a position of the imaging core within the patient according to several embodiments. An impedance-based system may include one or more catheter electrodes disposed on, or within, the IVUS catheter. For example, the one or more catheter electrodes may be disposed on the catheter jacket or integrated into the catheter jacket. The impedance- based system may also include one or more external electrodes. The one or more external electrodes may be placed on or disposed within one or more patches that are placed on the patients’ skin at one or more predetermined locations according to several embodiments. The one or more catheter electrodes and the one or more external electrodes may form an open circuit with at least one gap between the catheter electrode(s) and the external electrode(s). Atleast one processor, such as the processor 112, may be placed in electrical communication with the catheter electrode(s) and the external electrode(s).

[0127] During operation of the IVUS system that utilizes an impedance-based system, the at least one processor 112 may instruct the one or more catheter electrodes to generate electrical signal(s). The electrical signal(s) may travel through the patient to the one or more external electrodes, creating one or more return signals that correspond to each of the one or more external electrodes. In several embodiments, the at least one processer 112 may determine a location of the IVUS catheter, a longitudinal movement of the IVUS catheter, and / or a speed of the IVUS catheter based on an impedance of the one or more return electrical signals and the predetermined position(s) of the external electrode(s) on the patient’s skin. The at least one processor 112 may generate a three-dimensional map of the patient’s vasculature based on the location of the IVUS catheter as determined by the impedance-based system and the IVUS images captured during the procedure. In some embodiments, the impedance-based system may be implemented with the system-to-operator embodiments, the operator-to-system embodiments, the relative insertion depth device, and / or the encoder described above.

[0128] Several embodiments of medical imaging systems, such as IVUS systems are provided herein. Advantageously, according to several embodiments, such systems include one or more improvements beyond conventional IVUS systems, for example, enhanced imaging, image guided therapy, enhanced usability, easier setup, streamlined clinical workflow, reduced operating times, improved clinical efficacy, improved accuracy of diagnostic images, improved accuracy of therapeutic intervention delivery, improved guided interventional therapy, more efficient peripheral interventions, quicker informed treatment decisions, and quicker measurements and reporting. In some embodiments, IVUS is a diagnostic image-guided therapy-tool for the treatment of both peripheral arterial and venous disease, enabling 2D and / or 3D intraluminal visualization.

[0129] For example, image interpretation and measurement of luminal geometry with a flush-less catheter (e.g., diameter, stenosis, peripheral interventions, coronary interventions, atherectomy, lithotripsy, intravascular lithotripsy (IVL), balloon placement, stent placement, venous procedures, below the knee (BTK) procedures, AV Fistula, and other procedures are performed with embodiments described herein. Procedures can be performed by interventional cardiologists, radiologists, and / or vascular surgeons in hospitals, physicianoffices, Office Based Labs (OBL), and / or Ambulatory Surgery Centers (ASC). In several embodiments, systems described herein can be used efficiently in the hospital and OBL / ASC without specialized clinical support. An intervention may include therapy or other intervention such as peripheral interventions, coronary interventions, atherectomy, IVL, balloon placement, stent placement, venous procedures, BTK procedures, AV Fistula, and other procedures. Imaging can include, for example, IVUS non-coronary peripheral vessels, IVUS in coronary vessels, ultrasound, intraluminal imaging, imaging of body cavities and organs, and other imaging as described herein (and combinations thereof).

[0130] Many of these embodiments should be particularly advantageous to ensure that patients are not receiving unnecessary additional diagnostics or interventions, which in turn provides better patient care and reduces the short-term burden on the healthcare system. Likewise, many of these embodiments help patients receive the needed additional diagnostics or interventions they need, which in turn provides better patient outcomes and reduces the long-term burden on the healthcare system (by treating patients earlier in the disease progression timeline). In several embodiments, an IVUS system with a flush-less catheter provides a contemporary IVUS platform and catheter portfolio that provides improved usability with superior image interpretation and streamlined bedside workflow at a competitive cost enabling broader adoption.

[0131] In several embodiments, one or more of the following features are provided:

[0132] Plug and Play Catheter: According to several embodiments, flush-less catheters are optimized for vascular imaging and configured for superior pushability, tracking, and crossing for arterial and venous vasculature. In several embodiments, catheters have superior pushability to avoid kinking with sufficient column strength to advance the catheter through tortuous bends and occlusions in vasculature without buckling, over bending, or collapsing anywhere along the catheter (e.g., ability to cross an occlusion or constriction). In several embodiments, catheters have superior tracking for the ability of the catheter to follow a guidewire through tortuous bends in vasculature, having sufficient flexibility and strength to move along and advance along a guidewire to target locations within the vasculature. In several embodiments, catheters have superior crossing capabilities to cross occlusions, restrictions and constrictions within the vasculature, such as at sites with tissue blockage (e.g., stenoses, etc.) and / or implant blockages (such as stents, balloons, etc.). The systems described herein, suchas an IVUS catheter, can include a rotational design that is plug and play and for example, can allow the catheter to be taken out of the sterile package and prepared for use without the need to flush the device. In one embodiment, the catheter has a single rotational ultrasound element. In several embodiments, the catheter includes an encapsulated coupling medium (e.g., coupling medium, medium, liquid, fluid, gel, etc.) that supports the spinning imaging core inside the catheter jackets. In one embodiment, the IVUS catheter is a plug and play catheter with a rotational IVUS design flush-less peripheral disposable imaging catheter with a full length of 280 cm with a working length of 150 cm compatible with a 0.014” guidewire and a 5F sheath, allowing the IVUS catheter proximal connector to attach to a catheter interface module (CIM) outside of the sterile field. In one embodiment, the IVUS catheter is a plug and play catheter is a flush-less peripheral disposable imaging catheter with a full length of 250 cm with a working length of 110 cm compatible with a 0.035” guidewire and an 8F sheath, allowing the IVUS catheter proximal connector to attach to the CIM outside of the sterile field. Connecting outside of the sterile field optionally avoids having to drape a cabled motor unit inside of the sterile field. In several embodiments, the high definition (e.g., HD, ultra high definition (UHD), UHD, HD+, etc.) imaging uses acoustic pulse echoes with a matched excitation frequency spectrum for optimal penetration, ultra high resolution, and high definition image quality. In several embodiments, the system is optimized for peripheral vascular imaging, coronary imaging, or both. The imaging core spins inside the polymer jacket using an inner drive shaft connected through a proximal hub / connector in one embodiment. The hub connector is optionally attached to the CIM after removal from its sterile catheter package. The transducer located at the distal tip of the imaging core can rotate at between 1500 – 4000 rpm and receives echoes for processing into a circular image on the tablet display. The length of the catheter can be 8 to 10 feet long. In various embodiments the catheter can be taken out of the sterile package and prepared for use without the need to flush the device. The lengths can allow the catheter proximal connector to connect to the CIM outside of the sterile field. Connecting outside of the sterile field avoids having to drape a cabled motor unit inside of the sterile field in one embodiment. The catheter can include non-volatile memory that includes unique catheter identification, usage data, and calibration for optimal imaging performance. Calibration may include data related to measurements of electrical impedance versus frequency, acousticsensitivity versus frequency, and / or beam profile data that is specific to the individual device according to some embodiments.

[0133] Catheter Interface Module (CIM): A CIM is a hardware interface between the system cable from a workstation and disposable catheters according to several embodiments. In several embodiments, the CIM provides the system (e.g., IVUS system) with a rotational drive and ultrasound signal processing functions. Custom electronics may control the motor that rotates the imaging core inside the catheter. The electronics may also transmit and receive ultrasound signals between the spinning transducer within the distal end of the catheter tip and the custom printed circuit board inside the workstation. In various embodiments, the CIM provides an interface to read and write non-volatile memory in, for example, the catheter. Memory can be used to calibrate an ultrasound transducer for each unique catheter. In one embodiment, catheter memory may be used to select the appropriate system configuration to achieve the best possible imaging performance. The CIM may transmit ultrasound signals, sensor data, and / or catheter information from a catheter to a workstation and / or at least one user interface device (e.g., tablet, computer, etc.), which may store the transmitted information in a non-volatile memory in one or more locations. In one embodiment, the CIM is mounted on a bed rail outside a sterile field. In several embodiments, the CIM is embedded or integrated into imaging control equipment, a workstation, a housing, a table, a bed, a pedestal, a platform, and / or a cart. In several embodiments, the CIM is located outside a sterile field. One or more ports to allow for seamless connection between IVUS systems and other imaging modalities are provided in several embodiments.

[0134] Co-Registration of Images: In several embodiments, an IVUS system provides co-registration data to provide a 1:1 co-location identification enabling therapeutic precision. Advantageously, several embodiments described herein can work collaboratively with, or independently from, co-registration with another imaging modality such as fluoroscopy, in which a software algorithm tracks radio-opaque (RO) catheter marker(s) or a RO transducer throughout a continuous fluoroscopy recording. Co-registration with angiography may be used, for example, to determine 3D shape of vessel, lumen and lesion, including lesion length, efficient stent selection, efficient location for stent landing zone, in an attempt to shorten procedure time, decrease contrast use, and make practitioners morecomfortable with IVUS. Described herein, are several embodiments that accomplish one or more of these benefits with, or without, automated co-registration.

[0135] Synergies for Vascular Intervention: In several embodiments, the IVUS system is configured for optimized vascular procedures. Several systems and methods described herein can be used for peripheral, coronary and other intravascular applications. Other embodiments are used in non-vascular intraluminal applications, such as endoscopy.

[0136] For example, endoscopes may be used with several features described herein. Transvaginal and other gynecological ultrasound devices may also include several features described herein. For embodiments in which EUS (endoscopic ultrasound) and other intraluminal imaging or imaging of other body cavities or organs is performed (and such imaging is not in vessel), the features described herein for “IVUS” or “catheters” should be understood to apply to intraluminal (or other cavity / organ) catheters, probes, tubes, scopes and other such devices.

[0137] In some embodiments, the systems and methods are configured and optimized for peripheral vascular procedures (and not for coronary vascular procedures). In one embodiment, systems and methods configured, designed or adapted solely or primarily for the peripheral vasculature comprise one or more of the following features: flexibility, steerability, length, diameter, material, and / or bending strength for improved pushability, tracking, and crossing (e.g., the ability to cross through obstructions or narrowing) in the lumen. Some of these features may also be incorporated for applications other than peripheral IVUS. In some embodiments, the system is configured to image and / or measure tissue before a therapeutic procedure, such as to identify and plan the therapeutic procedure. In some embodiments, the system is configured to image and / or measure tissue after a therapeutic procedure, such as to confirm the results and outcome of the therapeutic procedure. In some embodiments, the system is configured to image and / or measure tissue during a therapeutic procedure.

[0138] Artificial Intelligence: In several embodiments, the systems described herein, including for example the advanced intravascular ultrasound platform, leverage AI to enable measurements, image interpretation, enhance total-system capabilities, and streamline workflows to maximize the clinical value. In some embodiments, advantageously, physicians will not need to integrate imaging data spatially and temporally to fully interpret the clinicalcondition. Instead, systems according to several embodiments described herein can leverage the power of AI with generational advancements to go beyond single image interpretation. In several embodiments, the AI-powered engine, for example, may include a workstation that enhances image interpretation with a simplified workflow improving overall useability. Machine learning is used in several embodiments. In one embodiment, the AI-ready processing power is designed to support real time and on-demand image interpretation. The AI powered workstation can provide high end processing and an AI engine for advanced signal and image processing. In various embodiments, the native image data capture provides for superior image interpretation (e.g., border detection, identification and measurement of vessel size, vessel disease, dissection, plaque morphology, etc.). In several embodiments, the systems described herein provide simplified measurement via automated border detection (e.g., AI algorithms automatically identify borders of a lumen, vessel, tissue, lesion, plaque, etc.). In several embodiments, the system provides simplified measurement via semi-automated border detection (e.g., the user can manually adjust or modify automated AI algorithms that identify borders of a lumen, vessel, tissue, lesion, plaque, etc. with the border selection reconfigured based on user modifications). In one embodiment, AI plaque identification utilizes AI algorithms to automatically classify and identify types of plaque within the imaged area to provide user guidance on treatment options (e.g., using color coding, icons or text overlays can be used to indicate what type of condition, such as plaque, may be present for the selected image). In several embodiments, the data driven platform is designed to collect data, simplify image interpretation, with AI processing power to support real time and on-demand image interpretation and reduce user cognitive load to help (i) identify lumen size, (ii) visualize dissections, (iii) characterize disease morphology, (iv) locate and quantify stenosis, and / or (v) identify true lumen. In some embodiments, image interpretation is used to identify thrombus, thrombosis, clots, embolisms, plaque, calcium, tissue health, stent or balloon apposition, and / or stent or balloon “health” or condition. Image interpretation may involve imaging to evaluate quality and / or position of placement of an existing stent. Image interpretation can involve identifying position relative to lumen walls, determine level of and / or quality of tissue grown into and around the stent or balloon. In one embodiment, for example with a bioresorbable stent, image interpretation can involve (i) evaluating the amount of dissolving of the stent, (ii) determining if the dissolving of the stent is in accordance with expected decay patterns (e.g.,determining whether the level of decay on one side of the stent similar to the other side of the stent, and if not, that may indicate a problem with stent placement, or if the stent is dissolving more rapidly than expected that could indicate the stent will not provide the tissue with the expected structural support). High-fidelity ultrasound data is used in one embodiment to drive improved image generation and image interpretation, with the option for leveraging artificial intelligence and / or machine learning. In various embodiments, catheters, devices, systems, and methods may be configured for use in performing edge-based machine learning computations associated with an image or image analysis using an artificial intelligence algorithm to identify a tissue border, plaque, calcium, thrombus, dissection, and / or stent apposition. In some embodiments, data, algorithms, AI and / or ML are used to obtain data from one or more sensors and provide feedback on operational aspects (such as imaging parameters) through a feedback loop (e.g., closed feedback loop / automated) or through user directed adjustments. In some embodiments, data, algorithms, AI and / or ML are used to obtain data from one or more images and provide feedback on operational aspects (such as imaging parameters and / or therapy) through a feedback loop (e.g., closed feedback loop / automated) or through user directed adjustments.

[0139] In several embodiments, imaging as described herein is used to diagnose whether a patient is suitable for a particular intervention or further diagnostics. In various embodiments, 2D and / or 3D intraluminal visualization is enabled. In one embodiment, 2D imaging includes an image in a single plane. In several embodiments, 3D imaging includes a volumetric representation of tissue or a lumen. In some embodiments, 3D imaging is reconstructed via algorithms interpolating a series of 2D images across a third dimension, taking a series of individual 2D images and estimating linear progression along the third dimension, and employing artificial intelligence (AI) to produce a 3D volumetric representation of the interpolated 2D images. In some embodiments, 3D model generation may involve obtaining 2D cross-sectional images of a vascular object such that a position along the vein or artery (e.g., an insertion length) can be recorded by an encoder or other sensor. Drawing each 2D cross section in 3D at the insertion length at which the cross section was recorded can allow a 3D model of the vascular object to be built. In one embodiment, adding an electro- magnetic sensor to the catheter tip can allow the position of the catheter tip to be recorded as the 2D images are obtained, thus allowing a 3D model of the vascular structure to be created.In one embodiment, one or more algorithms convert series of IVUS 2D images and signal data into volumetric 3D visualization. In one embodiment, 3D visualization is produced via interpolation of linear and / or nonlinear vascular structure geometry and acoustic reflections from a tissue. In one embodiment, pixel based interpolation is used to visualize vascular anatomy in three dimensions. In several embodiments, a series of cross sectional two dimensional IVUS images and / or signals are generated via pixel based cut view images of a vessel showing acoustic reflection information along a length of a lumen. In one embodiment, 3D visualization is produced via algorithms for creating anatomical contour borders via smooth 3D surface rendering. In several embodiments, AI is employed to create 3D visualization data and images.

[0140] In several embodiments coronary systems and methods are provided. In several embodiments, devices (such as coronary IVUS catheters) employ smaller diameters, higher rigidity, and modified coronary specific pushability, tracking, and / or crossing characteristics. Catheters for coronary applications may apply different ultrasound frequencies to account for variance in tissue lumen size: for example, the peripheral vasculature may have larger vessel diameters, so lower frequencies can be used for ultrasound imaging to image at farther distances from the IVUS catheter transducer. In some embodiments, coronary vessels have smaller diameters, so may use imaging ultrasound frequencies around 60 MHz, while peripheral imaging may use lower frequencies, such as around 40 MHz or less. In some embodiments, coronary IVUS catheters need less column strength for pushability or crossing because of the presence of a guide catheter.

[0141] In several embodiments, catheters are optimized for vascular imaging are configured for superior pushability, tracking, and crossing for arterial and venous peripheral vasculature. In several embodiments, one or more of the following features are provided:

[0142] Pushability: In several embodiments, catheters have superior pushability to avoid kinking with sufficient column strength to advance the catheter through tortuous bends and occlusions in vasculatures without buckling, over bending, or collapsing anywhere along the catheter (e.g., proximate or (e.g., ability to cross an occlusion or constriction). Material properties in some embodiments (e.g., balance of rigidity and flexibility, durometer in various segments), dimensional characteristics (e.g., larger dimensions, such a diameter and thickness, increase column strength, account for greater pushability and kink resistance.

[0143] Tracking: In several embodiments, catheters have superior tracking for the ability of the catheter to follow a guidewire through tortuous bends in vasculature, having sufficient flexibility and strength to move along and advance along a guidewire to target locations within the vasculature. Hydrophilic coatings according to some embodiments help reduce friction with the surrounding luminal tissue.

[0144] Crossing: In several embodiments, catheters have superior crossing capabilities to cross occlusions, restrictions and constrictions within the vasculature, such as at sites with tissue blockage (e.g., stenoses, etc.) and / or implant blockages (such as stents, balloons, etc.). According to some embodiments, crossing ability is enhanced by one or more of the following: (i) design of the distal tip (e.g., pointed enough to navigate occlusions, etc. and blunt enough not to snag on an occlusion), (ii) material properties (e.g., balance of rigidity and flexibility, durometer in various segments, etc.) and / or (iii) dimensional characteristics (e.g., larger dimensions, such a diameter and thickness, increase column strength). In one embodiment, low durometer near the distal tip is provided for flexibility to navigate tortuous anatomy and obstructions. In one embodiment, a region of varying or step wise gradient changes to a higher durometer proximally sufficient to push the catheter while avoiding kinking is provided. A single durometer and / or flexibility can remain constant along a certain or all portions of a device.

[0145] Changes and modifications in the embodiments described herein can be carried out without departing from the principles of the present disclosure. Each of the disclosed aspects and examples of the present disclosure may be considered individually or in combination with other aspects, examples, and variations of the disclosure. In addition, unless otherwise specified, none of the steps of the methods of the present disclosure are confined to any particular order of performance.

[0146] While the methods and devices described herein may be susceptible to various modifications and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail. Embodiments are not to be limited to the particular forms or methods disclosed, but rather intended is to cover modifications, equivalents, and alternatives falling within the spirit and scope of the various examples and embodiments described herein and / or in the appended claims. Further, the disclosure herein of any particular feature, aspect, method, property, characteristic, quality, attribute, element, or the like inconnection with an example can be used in all other examples set forth herein. Any methods disclosed herein need not be performed in the order recited. The use of sequential, or time- ordered language, such as “then,” “next,” “after,” “subsequently,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to facilitate the flow of the text and is not intended to limit the sequence of operations performed. Thus, some examples may be performed using the sequence of operations described herein, while other examples may be performed following a different sequence of operations.

[0147] Conditional language used herein, such as, among others, “can,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that some examples include, while other examples do not include, certain features, elements, and / or states. Thus, such conditional language is not generally intended to imply that features, elements, blocks, and / or states are in any way required for one or more examples or that one or more examples necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and / or states are included or are to be performed in any particular example. Where devices or methods “comprise” certain features or steps, such devices or methods may also “consist essentially of” such features or steps if identified as such in the claims. Where devices or methods “comprise” certain features or steps, such devices or methods may also “consist” of such features or steps if identified as such in the claims.

[0148] The methods disclosed herein may include certain actions taken by a practitioner; however, the methods can also include any user or third-party instruction of those actions, either expressly or by implication. For example, actions such as “positioning a device” include “instructing positioning of a device.”

[0149] The ranges disclosed herein also encompass any and all overlap, sub-ranges, and combinations thereof. Language such as “up to,” “at least,” “greater than,” “less than,” “between,” and the like includes the number recited. Numbers preceded by a term such as “about” or “approximately” include the recited numbers and should be interpreted based on the circumstances (e.g., as accurate as reasonable under the circumstances, for example ±5%, ±10%, ±15%, etc.). For example, “about 4 inches” includes “4 inches.” Phrases preceded by a term such as “substantially” include the recited phrase and should be interpreted based onthe circumstances (e.g., as much as reasonably possible under the circumstances). For example, “substantially linear” includes “linear.” Unless stated otherwise, all measurements are at standard conditions including temperature and pressure. The phrase “at least one of” is intended to require at least one item from the subsequent listing, not one type of each item from each item in the subsequent listing. For example, “at least one of A, B, and C” can include A; B; C; A and B; A and C; B and C; or A, B, and C.

Claims

WHAT IS CLAIMED IS:

1. A method of measuring a lengthwise distance between a series of images captured while an intravascular ultrasound (IVUS) catheter is moved by hand, the method comprising: moving the IVUS catheter along a longitudinal axis of the IVUS catheter with a hand, wherein the IVUS catheter comprises a plurality of markers disposed predetermined distances along a length of a longitudinal axis of the IVUS catheter, wherein the plurality of markers are visible by a complementary imaging modality; capturing a plurality of images with the complementary imaging modality while moving the IVUS catheter in a proximal direction or a distal direction along the longitudinal axis of the IVUS catheter; capturing with a recording device, one or more position inputs from a user that indicate a position of at least one of the plurality of markers with predetermined distances between markers relative to an anatomical point; associating the one or more position inputs with the plurality of images based on the position of the plurality of markers at a time each image of the plurality of images was captured; determining a longitudinal distance between the one or more images based on the predetermined spacing distance between markers; and determining an estimated longitudinal position for each of the plurality of images by interpolating the longitudinal distance between captured images at position inputs.

2. The method of claim 1, wherein the method does not require co-registration with another imaging technique, such as angiography.

3. The method of claim 1, wherein the plurality of markers are uniformly spaced by a uniform spacing distance in a range of 1 – 5 cm.

4. The method of claim 1, wherein the plurality of markers are uniformly spaced by a uniform spacing distance in a range of 2 – 50 mm.

5. The method of claim 1, wherein the one or more position inputs are provided by the user speaking a single word as each of the plurality of markers passes the anatomical point.

6. The method of claim 1, wherein the one or more position inputs are individual spoken words associated with a progress of each of the plurality of markers passes the anatomical point.

7. The method of claim 1, wherein the one or more position inputs comprise pressing a button.

8. The method of claim 1, wherein the one or more position inputs comprise tapping the IVUS catheter.

9. The method of any one of claims 1 - 8, the preceding claims, wherein the one or more position inputs comprise tapping a catheter interface module.

10. The method of any one of the preceding claims, wherein the one or more position inputs comprise stepping on a foot pedal.

11. The method of any one of claims 1 - 8, further comprising providing a visualization of the plurality of images with a distance based lengthwise axis.

12. The method of any one of claims 1 - 8, further comprising measuring / reporting the longitudinal distance between two sequential images of the plurality of images.

13. The method of any one of claims 1 - 8, further comprising measuring / reporting a distance between two or more images of the plurality of images.

14. The method of any one of claims 1 - 8, wherein the complementary imaging modality is X-ray fluoroscopy.

15. The method of claim 14, wherein the plurality of markers are seen in the fluoroscopy progressing past the anatomical point, and wherein the plurality of markers are seen directly progressing past an introducer sheath or some other fixed point outside the body.

16. The method of claim 14, wherein the plurality of markers are seen in the fluoroscopy progressing past the anatomical point, and wherein the plurality of markers are seen directly progressing past a guide catheter.

17. The method of any one of claims 1 - 8, wherein the moving the IVUS catheter with the hand is accomplished without using a linear actuation motor.

18. The method of any one of claims 1 - 8, wherein the IVUS catheter does not comprise a telescoping component.

19. A method of measuring a lengthwise distance between a series of images captured while an intravascular ultrasound (IVUS) catheter is moved by hand, the method comprising: inserting an IVUS catheter into a patient, wherein the IVUS catheter comprises: a catheter body, one or more ultrasound transducers disposed within the catheter body, and one or more markers disposed longitudinally along the catheter body; receiving one or more movement reporting inputs from a user; determining, via a processor, a length of the longitudinal movement based on the one or more movement reporting inputs, wherein the longitudinal movement is caused by a manual movement of the catheter body.

20. The method of claim 19, wherein the method does not require co-registration with another imaging technique, such as angiography.

21. The method of claim 19, wherein the one or more movement reporting inputs comprise one or more of a speech input, a mechanical input, a touch input, or a combination thereof.

22. The method of claim 19, wherein the one or more movement reporting inputs provide a rate of unidirectional movement.

23. The method of any one of claims 19 - 22, wherein the one or more movement reporting inputs comprise a reference position, wherein the reference position corresponds with an anatomical position of the catheter body relative to the patient.

24. The method of claim 23, wherein the one or more markers comprise one or more bands disposed on an external surface or inserted within the interior of the catheter body.

25. The method of any one of claims 19 - 22, wherein the one or more markers are radiopaque.

26. The method of any one of claims 19 - 22, further comprising detecting an error condition.

27. The method of claim 26, wherein the error condition is one of: an incorrect marker order, a repeated marker, a missing marker, or a non-uniform detection of the one or more markers.

28. An intravascular ultrasound (IVUS) catheter system configured for detecting a longitudinal position, the system comprising:a catheter body configured to be disposed within a lumen of a vessel of a patient; one or more markers disposed along the catheter body; and a processor configured to: receive one or more movement reporting inputs from a user; determine a lengthwise movement based on the one or more movement reporting inputs; and provide an output to a user based on the longitudinal movement.

29. The system of claim 28, wherein the system does not require co-registration with another imaging technique, such as angiography.

30. The system of claim 28, wherein the one or more movement reporting inputs comprise one or more of: a speech input, a mechanical input, a touch input, or a combination thereof.

31. The system of claim 28, wherein the one or more markers comprise one or more bands disposed on an external surface or inserted within the interior of the catheter body.

32. The system of any one of claims 28 - 31, wherein the one or more markers are radiopaque.

33. The system of any one of claims 28 - 31, wherein the processors is further configured to detect an error condition.

34. The system of claim 33, wherein the error condition is one of: an incorrect marker order, a repeated marker, a missing marker, or a non-uniform detection of the one or more markers.

35. A method of measuring a lengthwise distance between a series of images captured while an intravascular ultrasound (IVUS) catheter is moved by hand, the method comprising: moving the IVUS catheter along a longitudinal axis of the IVUS catheter with a hand, wherein the IVUS catheter comprises a plurality of markers along a length of a longitudinal axis of the IVUS catheter, wherein the plurality of markers are visible by a complementary imaging modality; providing a plurality of pacing outputs to a user based on a programmed rate of unidirectional movement;storing a plurality of images of a series of positions of the plurality of markers relative to an anatomical point; and determining an estimated longitudinal position for each of the plurality of images based on the programmed rate of movement.

36. The method of claim 35, wherein the method does not require co-registration with another imaging technique, such as angiography.

37. The method of claim 35, further comprising measuring / reporting the longitudinal distance between two sequential images of the plurality of images.

38. The method of claim 35, further comprising measuring / reporting a distance between two or more images of the plurality of images.

39. The method of claim 35, further comprising prompting the user to accept or reject the estimated longitudinal position for each of the plurality of images.

40. The method of any one of claims 35 - 39, wherein the plurality of pacing outputs are audible.

41. The method of any one of claims 35 - 39, wherein the plurality of pacing outputs are haptic.

42. The method of any one of claims 35 - 39, wherein the plurality of pacing outputs are visual.

43. The method of any one of claims 35 - 39, further comprising providing a visualization of the plurality of images with a distance based lengthwise axis.

44. The method of any one of claims 35 - 39, wherein the plurality of markers are uniformly spaced by a uniform spacing distance in a range of 1 – 5 cm.

45. The method of any one of claims 35 - 39, wherein the plurality of markers are uniformly spaced by a uniform spacing distance in a range of 2 – 50 mm.

46. A method of measuring a lengthwise distance between a series of images captured while an intravascular ultrasound (IVUS) catheter is moved by hand, the method comprising: inserting an IVUS catheter into a patient, wherein the IVUS catheter comprises: a catheter body, one or more ultrasound transducers disposed within the catheter body, and one or more markers disposed longitudinally along the catheter body; providing one or more pacing instructions to a user; anddetermining, via a processor, a length of a longitudinal movement of the catheter body based on the one or more pacing instructions, wherein the longitudinal movement is caused by a manual movement of the catheter body.

47. The method of claim 46, wherein the method does not require co-registration with another imaging technique, such as angiography.

48. The method of claim 46, wherein the one or more pacing instructions dictate a longitudinal movement speed to the user.

49. The method of claim 48, wherein the longitudinal movement speed in a range of 1 – 20 mm / sec.

50. The method of claim 48 further comprising receiving the longitudinal movement speed from the user.

51. The method of any one of claims 46 - 50, wherein the one or more pacing instructions comprise one or more of: an audio output, a haptic output, and a visual output.

52. The method of any one of claims 46 - 50, further comprising: collecting IVUS images; and annotating the IVUS images based on the longitudinal movement of the catheter body.

53. The method of any one of claims 46 - 50, wherein the one or more markers comprise one or more bands disposed on an external surface or inserted within an interior of the catheter body.

54. The method of any one of claims 46 - 50, wherein the one or more markers are radiopaque.

55. The method of any one of claims 46 - 50, further comprising detecting an error condition.

56. The method of claim 55, wherein the error condition is one of: an incorrect marker order, a repeated marker, a missing marker, or a non-uniform detection of the one or more markers.

57. An intravascular ultrasound (IVUS) catheter system configured for detecting a longitudinal position, the system comprising: a catheter body configured to be disposed within a lumen of a vessel of a patient; one or more markers disposed along the catheter body; and a processor configured to:provide one or more pacing instructions to a user; determine a length of the longitudinal movement based on the one or more pacing instructions; and provide an output to a user based on the longitudinal movement.

58. The system of claim 57, wherein the system does not require co-registration with another imaging technique, such as angiography.

59. The system of claim 57, wherein the one or more pacing instructions dictate a longitudinal movement speed to the user.

60. The system of claim 59, wherein the longitudinal movement speed is in a range of 1 – 20 mm / sec.

61. The system of any one of claims 57 - 60, wherein the processor is configured to receive the longitudinal movement speed from the user.

62. The system of any one of claims 57 - 60, wherein the one or more pacing instructions comprise one or more of: an audio output, a haptic output, a visual output, or a combination thereof.

63. The system of any one of claims 57 - 60, wherein the processor are further configured to: collect IVUS images; and annotate the IVUS images based on the longitudinal movement of the catheter body.

64. The system of any one of claims 57 - 60, wherein the one or more markers are radiopaque.

65. The system of any one of claims 57 - 60, wherein the processor are further configured to detect an error condition.

66. The system of claim 65, wherein the error condition is one of: an incorrect marker order, a repeated marker, a missing marker, or a non-uniform detection of the one or more markers.

67. A method of measuring a lengthwise distance between a series of images captured while an intravascular ultrasound (IVUS) catheter is moved by hand, the method comprising: moving the IVUS catheter along a longitudinal axis of the IVUS catheter with a hand,capturing a plurality of images with the IVUS catheter while moving the IVUS catheter in a proximal direction or a distal direction along the longitudinal axis of the IVUS catheter; measuring a distance travelled by the IVUS catheter with an encoder not associated with a mechanical actuator or motor; associating an image or tissue feature in the plurality of images with the distance travelled by the IVUS catheter; and determining a longitudinal length between images of the tissue feature based on the distance measured by the encoder.

68. The method of claim 67, wherein the method does not require co-registration with another imaging technique, such as angiography.

69. The method of any one of claims 67 - 68, wherein the encoder is optical.

70. The method of any one of claims 67 - 68, wherein the encoder is inductive.

71. The method of any one of claims 67 - 68, wherein the encoder is capacitive.

72. The method of any one of claims 67 - 68, wherein the encoder comprises a mechanical wheel.

73. An intravascular ultrasound (IVUS) catheter system configured for detecting a longitudinal position, the system comprising: a catheter body configured to be disposed within a lumen of a vessel of a patient; one or more markers disposed along the catheter body; an encoder configured to measure a rate of movement of the one or more markers when the catheter body is moved longitudinally by hand; and provide capacity to measure / report an output length or lengths to a user based on the movement of the catheter body by hand.

74. The system of claim 73, wherein the system does not require co-registration with another imaging technique, such as angiography.

75. The system of any one of claims 73 - 74, wherein the encoder is optical.

76. The system of any one of claims 73 - 74, wherein the encoder is inductive.

77. The system of any one of claims 73 - 74, wherein the encoder is capacitive.

78. The system of any one of claims 73 - 74, wherein the encoder comprises a mechanical wheel.

79. The system of any one of claims 73 - 74, comprising a Linear Variable Differential Transformer (LVDT).

80. The method of any one of Claims 1-25, 33-53, and 64-65, further comprising measuring a movement of the IVUS catheter with an encoder.

81. The method of any one of Claims 67 - 71, further comprising measuring a movement of the IVUS catheter with an encoder.

82. An intravascular ultrasound (IVUS) catheter system configured for detecting a longitudinal position, the system comprising: a catheter body configured to be disposed within a lumen of a vessel of a patient, the catheter body comprising: an imaging core configured to capture a plurality of IVUS images; and one or more catheter electrodes; one or more external electrodes disposed on a skin of a patient; and at least one processor configured to be placed in electrical communication with the one or more catheter electrodes and the one or more external electrodes, the at least one processor configured to: instruct the one or more catheter electrodes to generate one or more electrical signals; receive, via the one or more external electrodes, one or more return electrical signals; and determine an intracorporal location of the imaging core based on an impedance of each of the one or more return electrical signals.

83. The system of claim 82, wherein the at least one processor is further configured to generate a three-dimensional map of the patient’s vasculature based on the intracorporal location of the imaging core during an IVUS imaging procedure and the plurality of IVUS images.

84. The system of claim 82, further comprising one or more patches configured to be placed on the skin of the patient, wherein the one or more external electrodes are disposed on or in the one or more patches.

85. The system of any one of claims 82 - 84, wherein the catheter body comprises a catheter jacket, and wherein the one or more catheter electrodes are disposed on the catheter jacket.

86. The system of any one of claims 82 - 84, wherein the catheter body comprises a catheter jacket, and wherein the one or more catheter electrodes are disposed within the catheter jacket.

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