Steerable Biopsy Needle with Optical Shape Sensing
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Solution Overview
Problem
Current MRI-guided interventions face limitations in tracking deviations of needles and catheters during manipulation, causing positioning errors and procedural complications due to the need for MRI system use, susceptibility artifacts from metallic devices, and inability to measure lumen roughness.
Innovation Solution
The development of biopsy and catheter devices equipped with optical fibers featuring fiber Bragg gratings (FBGs) that allow for strain measurement, enabling shape and deflection sensing, and integration of shape memory alloys (SMAs) for steerable mechanisms, which are MRI-compatible and do not interfere with imaging processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If metallic devices with electronic sensors are used for tracking, then positioning accuracy can be improved, but susceptibility artifacts cause distortions leading to poor signal and inaccurate position information
Solution Approach 1:
The patent replaces metallic electronic sensors with optical fiber sensors containing Fiber Bragg Gratings (FBGs). Optical fibers are non-metallic and MRI-compatible, eliminating susceptibility artifacts while enabling precise measurement of needle deflection through optical strain detection. The FBGs reflect specific wavelengths of light that shift in response to strain, providing accurate position feedback without magnetic interference.
Solution Approach 2:
The patent introduces optical fibers as an intermediary medium between the needle and the MRI system. Instead of placing electronic sensors directly in the magnetic field, the optical fibers transmit mechanical strain information from the needle to external optical interrogators, which convert the strain into position information. This intermediary approach isolates the sensing mechanism from harmful magnetic field effects.
2Adaptability or versatility
If electronic apparatus is integrated into interventional devices for tracking, then device functionality is improved, but device complexity increases including adding the need for appropriate patient isolation electronics
Solution Approach 1:
The patent substitutes electronic sensing components with passive optical fiber sensors. Optical fibers contain no electronic components, eliminating the need for patient isolation electronics, ground loops, or complex electromagnetic shielding. The entire sensing system relies on optical principles rather than electrical circuits, dramatically simplifying the device architecture for MRI-compatible applications.
Solution Approach 2:
The patent extracts all electronic components from the interventional device itself, placing the electronic interrogation system outside the patient's body. The optical fibers serve as pure mechanical-strain-to-optical-signal transducers with no embedded electronics, separating the sensing function from electronic processing and eliminating the complexity of integrating electronic apparatus into the medical device.
3Speed
If rapid MRI or gradient-based tracking methods are used, then real-time tracking is achieved, but the device must be within the homogeneous volume of the gradient fields used for imaging
Solution Approach 1:
The patent uses optical fibers as intermediaries that extend the sensing capability beyond the limited homogeneous gradient field volume. The fibers can be routed along the entire length of the needle, allowing strain measurement at multiple positions including regions outside the immediate gradient field homogeneity zone. This enables real-time tracking throughout the full insertion path, not just within the imaging slice.
Solution Approach 2:
The patent transitions from relying solely on the three-dimensional gradient field volume for tracking to using an additional dimensional approach: optical fiber length. By distributing FBGs along the fiber length, the system gains extended measurement coverage in the longitudinal dimension of needle insertion, overcoming the limited spatial coverage of gradient-based methods.
4Measurement precision
If optical fibers with FBGs are used for shape sensing, then measurement precision is improved, but the device requires integration of optical components
Solution Approach 1:
The patent makes the optical fiber serve multiple functions simultaneously: it acts as both the structural reinforcement element within the needle and the sensing element for shape measurement. The FBGs are written directly into the fiber during manufacturing, integrating the sensing capability into the fiber itself rather than requiring separate sensor assemblies. This multi-functionality reduces the number of discrete components and simplifies integration.
Solution Approach 2:
The patent merges the optical fiber with the needle structure by embedding the fiber within the needle's construction. The fiber runs co-axially or adjacent to the needle elements, and the FBGs are positioned at specific locations along the needle length. This merging of structural and sensing functions eliminates the need for separate sensor mounting hardware and simplifies the overall device architecture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These devices can accurately measure small strains and provide precise tracking and steering within MRI environments, reducing positioning errors and allowing for the assessment of lumen roughness, enhancing the accuracy and safety of interventional procedures.
Implementation Method 1
Fiber Bragg Grating (FBG) sensors reflect optical energy with a peak wavelength that shifts in proportion to the strain to which a particular FBG is subjected
Implementation Method 2
the deflection grating of the corresponding fiber having the angled grating forming a measurement of the resultant deflection caused by the SMA contraction
Data Source
AI summary
A biopsy needle has a central axis and includes one or more sensing regions, each sensing region formed by a plurality of sensing optical fibers located over a particular extent of said central axis and inside the outer shell of the needle. The sensing optical fibers are coupled to a wavelength interrogator. A steerable catheter has a central axis and outer shell, the outer shell coupled to a plurality of optical fibers in sensing regions and actuation regions, the sensing regions formed over particular extents of the central axis by bonding gratings to the inner surface of the outer shell, and the actuation regions formed by coupling optical energy into shape memory alloys bonded to the outer shell.