Angiographic examination procedure

Abstract

Angiographic examination procedure of an object of study (6, 13) to determine morphology, histology and / or condition of moving walls of vessels (15, 20) comprising the following steps: S1 Acquisition of a series (13, 16) of angiographic images (14, 17) of a section of interest (20) of a vessel (15, 20), S2 quantitative analysis of the vessel wall (21) of the section (20) of the vessel (15, 20), S3 Calculation of the intrinsic movement (26, 27) of the vessel wall (21) in relation to expansion and contraction of the vessel (15, 20) from each of two consecutive angiographic images (14, 17) and S4 Visualization of the difference in intrinsic movement (26, 27) of the vessel wall (21) and / or S5 Visualization of the morphology and / or histology of the vessel wall (21).

Description

[0001] The invention relates to an angiographic examination method for determining the morphology, histology, and / or properties of moving vessel walls. Such an examination method can be used, for example, with an X-ray diagnostic device known from US 7,500,784 B2 and described below. Fig. 1 is explained.

[0002] The Fig. Figure 1 shows an example of a monoplane X-ray system with a C-arm 2 held by a stand 1 in the form of a six-axis industrial or articulated robot, at the ends of which an X-ray source, for example an X-ray emitter 3 with X-ray tube and collimator, and an X-ray image detector 4 as an image acquisition unit are attached.

[0003] By means of the articulated robot known, for example, from US 7,500,784 B2, which preferably has six axes of rotation and thus six degrees of freedom, the C-arm 2 can be adjusted spatially as desired, for example, by rotating it about a center of rotation between the X-ray source 3 and the X-ray image detector 4. The angiographic X-ray system 1 to 4 according to the invention is rotatable, in particular, about centers of rotation and axes of rotation in the C-arm plane of the X-ray image detector 4, preferably about the center of the X-ray image detector 4 and axes of rotation intersecting the center of the X-ray image detector 4.

[0004] The well-known articulated robot has a base frame, which is, for example, fixed to a floor. A carousel is attached to this frame and can rotate around a first axis. A robot arm is mounted on the carousel and can pivot around a second axis. A robot arm is attached to the arm and can rotate around a third axis. A robot hand is mounted at the end of the robot arm and can rotate around a fourth axis. The robot hand has a mounting element for the C-arm 2, which can pivot around a fifth axis and rotate around a sixth axis of rotation perpendicular to it.

[0005] The implementation of the X-ray diagnostic system does not depend on an industrial robot. Conventional C-arm devices can also be used.

[0006] The X-ray image detector 4 can be a rectangular or square, flat semiconductor detector, preferably made of amorphous silicon (a-Si). However, integrating and possibly counting detectors, for example using CMOS technology, can also be employed. The use of conventional X-ray image intensifier television chains is also possible.

[0007] In the beam path of the X-ray tube 3, a patient 6 is positioned on a tabletop 5 of a patient positioning table. A control unit 7 with an imaging system 8 is connected to the X-ray diagnostic device. This system receives and processes the image signals from the X-ray image detector 4 (operating elements, for example, are not shown). The X-ray images can then be viewed on displays of a monitor 9.

[0008] Instead of the one in Fig. Any angiographic X-ray system can be used with the stand 1 shown for example in the form of the six-axis industrial or articulated robot, for example one that has a normal ceiling- or floor-mounted bracket for the C-arm 2.

[0009] Instead of the C-arm 2 shown, for example, the angiographic X-ray system can also have separate ceiling- and / or floor-mounted brackets for the X-ray tube 3 and the X-ray image detector 4, which are, for example, electronically rigidly coupled.

[0010] Sensors 10, which are attached, for example, to the chest of patient 6, can record the ECG signals of patient 6 and transmit them to a processing circuit 11 in the system control unit 7. The ECG signals of patient 6 can also be recorded intracardiacally using an ECG catheter (not shown).

[0011] Currently, blood vessels, such as coronary arteries, but also other vessels, are visualized in 2D or 3D during interventional procedures. This is achieved by injecting contrast medium during an X-ray examination (angiography). From this examination, the physician can infer the morphology of the vessel, but not the condition of the vessel wall. Furthermore, stenoses or aneurysms can be detected and subsequently treated.

[0012] More and more methods, such as OCT (optical coherence tomography) or FFR (fractional flow reserve), are being established and used to determine the characteristics of the vessel walls and subsequently to provide the best possible treatment for the patient. For example, the wall structure of the vessel can be determined using IVUS (intravascular ultrasound) or IVUS-VH (virtual histology).

[0013] However, this means that a second examination results in an additional burden for the patient, an increased dose burden for both doctor and patient, and significant additional costs for the healthcare system.

[0014] To determine the morphology, histology and / or the condition of vessels, a combination of X-ray and additional methods must always be used.

[0015] Alternatively, other imaging techniques such as CT and / or MR can also be used to determine the morphology and condition of the vessel wall, but angiography is still considered the gold standard in imaging.

[0016] Furthermore, the subsequent treatment will again take place in the cardiac catheterization or angiography laboratory.

[0017] From DE 10 2009 010 291 A1, a method for determining and classifying wall motion abnormalities of a myocardium is known, wherein a time series of image datasets depicting the myocardium is evaluated. This involves segmenting the myocardium in the image datasets, determining one or more parameter values ​​for one or more parameters based on the segmented image datasets, and evaluating the parameter values ​​using a trained classifier.

[0018] DE 10 2007 018 749 A1 relates to a method for assessing the risk of aneurysm rupture from time-resolved images, in which an X-ray contrast agent is injected into a patient with an aneurysm, an ECG signal is used to trigger an image acquisition run, a sequence of 2D fluoroscopy images is acquired together with a corresponding ECG signal value, a C-arm of the X-ray diagnostic device is rotated during the image acquisition run, the images in the fluoroscopy image sequence are acquired from a rotating viewpoint, the images in the fluoroscopy image sequence are sorted into time windows of the cardiac cycle based on the ECG signal, and one or more volume datasets of the aneurysm are reconstructed from the two-dimensional fluoroscopy image sequence.

[0019] The invention is based on the objective of enabling a simple representation of the morphology, histology and / or the condition of vessels using only one diagnostic device.

[0020] The problem is solved according to the invention for an investigation method of the type mentioned at the outset by the features specified in claim 1. Advantageous embodiments are specified in the dependent claims.

[0021] The task is solved for an angiographic examination procedure using the following steps. S1 Acquisition of a series of angiographic images of a section of interest in a vessel, S2 quantitative analysis of the vessel wall of the section of the vessel, S3 Calculation of the intrinsic movement of the vessel wall in relation to expansion and contraction of the vessel from each pair of consecutive angiographic images and S4 Visualization of the difference in the intrinsic movement of the vessel wall, the morphology and / or histology of the vessel wall.

[0022] This provides the person examining the vessel with a monitor image from which they can easily recognize the condition of the vessels being examined.

[0023] According to the invention, in a fifth step S5 the morphology and / or histology of the vessel wall can be visualized.

[0024] The calculation of the movements of the vessel walls according to the invention becomes more accurate if the acquisition of the angiographic images according to step S1 is carried out over at least one ECG cycle.

[0025] The determination of the movements of the vessel walls can be improved according to the invention if the acquisition of the angiographic images according to step S1 is carried out with a high frame rate, for example with 25 / 30 Hz.

[0026] To reduce motion blur, it has proven advantageous to acquire the angiographic images according to step S1 using short X-ray pulses, for example with a duration of 6 to 12 ms.

[0027] According to the invention, the angiography images acquired according to step S1 can be fluoroscopy images or subtraction images.

[0028] Advantageously, the calculation of the intrinsic movement of the vessel wall according to step S3 can be carried out by determining the difference between the maximum expansion and minimum contraction of the vessel wall.

[0029] It has proven advantageous to visualize the intrinsic movement of the vessel wall according to step S4 using arrows corresponding to the magnitude of the movement. Alternatively, according to the invention, the intrinsic movement of the vessel wall according to step S4 can be visualized using markings corresponding to the magnitude of the movement. According to the invention, the intrinsic movement of the vessel wall according to step S4 can be visualized using colored markings corresponding to the magnitude of the movement, where, for example, green can indicate an intact vessel wall and red a critical one.

[0030] According to the invention, the vessel to be examined can be an artery, in particular the aorta.

[0031] Advantageously, the acquisition of the angiographic images according to step S1 can be carried out using an X-ray system, in particular a device for creating rotational angiographies for soft tissue imaging, for example using DynaCT ®, for example in 3-D.

[0032] It has proven advantageous to create 2-D series for the acquisition of angiographic images according to step S1, or to generate a 3-D reconstruction from at least two 2-D projections.

[0033] The invention is explained in more detail below with reference to exemplary embodiments shown in the drawing. The drawing shows: Fig. 1 a known C-arm angiography system with an industrial robot as a support device, Fig. 2 a well-known DSA procedure (state-of-the-art), Fig. 3 a vessel section with its wall movements, Fig. 4 an alternative representation of the wall movements of the vessel segment and Fig. 5 process steps of an angiographic examination method according to the invention.

[0034] For example, in Fig. In the two known DSA (digital subtraction angiography) procedures described, a pure native image 12 (anatomy only) is generated, for example, of a skull 13 as a so-called mask image, along with a series of native images 14 taken under fluoroscopy from the entire filling phase, in which a vascular tree 15 is filled with contrast medium. The series of fluoroscopy images 14, showing the skull 13 and the contrast-filled vascular tree 15, and the native image 12 or mask image are subtracted from each other in a subtraction step 16. Further image processing steps, such as contrast adjustment, edge enhancement, etc., can follow until a current image sequence 17 of subtraction images is obtained in which only the vascular tree 15 is clearly visible, with the display typically such that the vascular tree 15 appears bright against the dark background.

[0035] In the Fig. Figure 3 shows a vessel segment 20, for example, of the vascular tree 15, as the object to be examined, with a vessel wall 21 that has a bifurcation 22. The direction of blood flow 23 and, if applicable, contrast medium flow is indicated by an arrow. The vessel segment 20 exhibits, for example, a calcification 24 and a plaque 25, such as cholesterol, which lead to a stiffening of the vessel wall 21 in these affected areas, while the remaining parts of the vessel wall 21 retain their normal flexibility. This is illustrated by double arrows that make the wall movements 26 visible. These wall movements 26 are partially zero in the area of ​​the calcification 24 and the plaque 25, while they are at their maximum in the remaining areas outside the affected regions, as illustrated by the different lengths of the double arrows.

[0036] In the Fig. Figure 4 shows another type of visualization according to the invention. Starting from the one in Fig. In the vessel segment 20 shown in Figure 3, the wall movements 26, depicted there as double arrows, are visualized as markings of the intrinsic movements 27 of the vessel wall 21, indicating the difference between maximum expansion and minimum contraction. The minima of this difference, i.e., the areas of constriction marked by the intrinsic movements 27, indicate the location 28 of the calcification 24 and the position 29 of the plaque 25.

[0037] The object to be examined can be, as exemplified by the Fig. 2, Fig. 3 to Fig. 4 shown, the vessel section 20 of the vascular tree 15, but can also generally be a cavity, a hollow chamber, a hollow organ or hollow vessel, in particular the heart, or an artery, in particular the aorta.

[0038] In the Fig. Section 5 now describes and illustrates the process sequence according to the invention in more detail. In a first step S1, a series 14 or 17 of angiographic images 14 or 17 of a vessel segment 20 of interest within a cavity 15 is acquired. It is important to note that the acquisition must be performed over at least one ECG cycle with the highest possible frame rate and the shortest possible pulses. The angiographic images 14 or 17 then have sufficiently good quality for the further and complete calculation of the intrinsic movements 26 or 27 of the vessel wall 21.

[0039] Subsequently, according to a second step S2, a quantitative vascular analysis of the vessel wall 21 of the vessel segment 20 of the cavity is carried out, by means of which the morphology, histology and / or the condition of vessels, especially the vessel wall, can be determined and represented.

[0040] According to a third step S3, the intrinsic movements 26 or 27 of the vessel wall 21 are calculated from each of two consecutive angiography images 14 or 17, whereby, for example, the differences of the maximum extension or expansion and minimum contraction of the vessel wall 21 are determined for several points on the vessel wall 21.

[0041] In a fourth step S4, the differences in the intrinsic movements 26 or 27 of the vessel wall 21 are visualized. This can be done, for example, by the double arrows which, according to Fig. 3. The length of the markers indicates the magnitude of the wall movements 26. Alternatively, the intrinsic movement 26 or 27 of the vessel wall 21 can be visualized according to step S4 by markings corresponding to the magnitude of the intrinsic movement 27. These markings or double arrows can be color-coded, with, for example, green indicating an intact vessel wall and red indicating a critical one.

[0042] According to a fifth and final step S5, the morphology and / or histology of the vessel wall 21 can be visualized.

[0043] The time-resolved imaging (2-D + time and / or 3-D + time) of vessels makes it possible to simultaneously determine the morphology, histology and / or condition of the vessel wall in an angiography examination.

[0044] The inventive method utilizes the effect of the so-called "biological Windkessel effect." The so-called "physiological Windkessel" consists of the expansion and subsequent contraction of the walls of arteries near the heart, especially the aorta or large arteries. During systole, the heart pumps blood, while blood flow ceases during diastole. During systole, the phase of blood ejection through contraction of the heart muscle, the Windkessel arteries expand, thus absorbing an additional portion of the stroke volume, which is passively expelled during diastole, the relaxation phase of the heart muscle. This reduces the significant pressure difference between systole and diastole.

[0045] The vessel diameter therefore varies with each pulse. This small variation is determined and displayed according to the invention. Areas that are stenotic, for example due to calcification, should show less or no variation than areas that do not have stenosis.

[0046] This can be compared to the heart muscle, which in the case of myocardial necrosis is partially necrotic. This is a fact that is utilized in the so-called "quantitative assessment of regional wall movements" during an examination of the left ventricle. In the area of ​​necrotic myocardial tissue, almost no intrinsic movement is detectable (for example, "akinesia"). Thus, one can conclude that the coronary artery supplying this part of the myocardium is stenotic.

[0047] For this procedure, angiographic images 14 or 17 of the vessel segment of interest are recorded over at least one ECG cycle with the highest possible frame rate and shortest possible pulses to reduce motion blur. Standard quantitative vascular analysis applications are then used to determine and display the morphology and / or histology, particularly of the vessel wall. The intrinsic motion (expansion or contraction) of the vessel wall is then calculated from each pair of consecutive images. This delta of motion is subsequently visualized for further analysis.

[0048] Time-resolved imaging of blood vessels makes it possible to simultaneously determine the morphology, histology, and / or condition of the vessel wall during angiography. This drastically reduces both the radiation dose and the effort involved, including time and costs. Additional examination methods such as IVUS, IVUS-VH, OCT, FFR, etc., are no longer necessary, nor is the additional radiation exposure for examiners and patients required for navigating these supplementary methods with guidewires and / or catheters.

Claims

[1] Angiographic examination procedure of an object of study (6, 13) to determine the morphology, histology and / or condition of moving walls of vessels (15, 20) comprising the following steps: S1 Acquisition of a series (13, 16) of angiographic images (14, 17) of a section of interest (20) of a vessel (15, 20), S2 quantitative analysis of the vessel wall (21) of the section (20) of the vessel (15, 20), S3 Calculation of the intrinsic movement (26, 27) of the vessel wall (21) in relation to expansion and contraction of the vessel (15, 20) from each of two consecutive angiographic images (14, 17) and S4 Visualization of the difference in intrinsic movement (26, 27) of the vessel wall (21) and / or S5 Visualization of the morphology and / or histology of the vessel wall (21). [2] Angiographic examination method according to claim 1, characterized by, that the acquisition of the angiographic images (14, 17) according to step S1 is carried out over at least one ECG cycle. [3] Angiographic examination method according to one of claims 1 or 2, characterized by , that the acquisition of the angiographic images (14, 17) according to step S1 is carried out with a high frame rate. [4] Angiographic examination method according to any one of claims 1 to 3, characterized by , that the acquisition of the angiographic images (14, 17) is carried out according to step S1 with short X-ray pulses. [5] Angiographic examination method according to any one of claims 1 to 4, characterized by , that the angiography images (14, 17) acquired according to step S1 are fluoroscopy images (14) or subtraction images (17). [6] Angiographic examination method according to any one of claims 1 to 5, characterized by, that the calculation of the intrinsic movement (26, 27) of the vessel wall (21) according to step S3 is carried out by determining the difference of the maximum expansion and minimum contraction of the vessel wall (21). [7] Angiographic examination method according to any one of claims 1 to 6, characterized by , that the visualization of the intrinsic movement (26, 27) of the vessel wall (21) according to step S4 is carried out by arrows corresponding to the size of the intrinsic movement (26). [8] Angiographic examination method according to any one of claims 1 to 7, characterized by , that the visualization of the intrinsic movement (26, 27) of the vessel wall (21) according to step S4 is carried out by markings (27) corresponding to the size of the intrinsic movement. [9] Angiographic examination method according to claim 8 or 8, characterized by, that the visualization of the intrinsic movement (26, 27) of the vessel wall (21) according to step S4 is carried out by colored arrows and / or markings (27) corresponding to the size of the intrinsic movement. [10] Angiographic examination method according to any one of claims 1 to 9, characterized by that the vessel to be examined is an artery, in particular the aorta. [11] Angiographic examination method according to any one of claims 1 to 10, characterized by , that the acquisition of the angiographic images (14, 17) according to step S1 is carried out using an X-ray system. [12] Angiographic examination method according to any one of claims 1 to 11, characterized by , that the acquisition of the angiographic images (14, 17) according to step S1 is carried out using a device for creating rotational angiographies for soft tissue imaging. [13] Angiographic examination method according to any one of claims 1 to 12, characterized by, that the acquisition of the angiography images (14, 17) according to step S1 is carried out in 3-D. [14] Angiographic examination method according to any one of claims 1 to 13, characterized by , that 2-D series are created to acquire the angiographic images (14, 17) according to step S1. [15] Angiographic examination method according to any one of claims 1 to 14, characterized by , that to acquire the angiographic images (14, 17) according to step S1 a 3-D reconstruction is generated from at least two 2-D projections.

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