Steerable Guide for LITT Using Nitinol Wire and Spring Mechanism
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Solution Overview
Problem
Current LITT procedures face challenges with irregularly shaped brain tumors due to their linear trajectory limitations, leading to incomplete ablation, increased procedural time, and risk to healthy tissue, especially when lesions are deep or surrounded by critical structures.
Innovation Solution
A steerable guide for LITT that allows deployment of a laser fiber along a controlled curved trajectory with micro-adjustability, utilizing a nitinol wire and spring mechanism to curve the needle within a rigid outer tube, enabling three-dimensional freedom for precise tumor access and ablation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a straight catheter is used for LITT, then the procedure is minimally-invasive, but it cannot completely ablate irregular shaped lesions
Solution Approach 1:
The needle assembly transitions from a static straight configuration to a dynamic curved configuration through the spring-loaded mechanism. The spring can be compressed to straighten the needle for insertion, then released to curve the needle tip for precise positioning within irregular lesions, enabling complete ablation while maintaining minimal invasiveness
Solution Approach 2:
The curvature radius of the needle is changed by adjusting the spring compression. By varying the compression distance, the needle can achieve different curvature radii to match the specific geometry of irregular lesions, allowing the catheter to adapt to various lesion shapes and achieve complete ablation
2Manufacturing precision
If multiple trajectories are planned to cover irregular lesions, then complete ablation is achieved, but procedural time increases
Solution Approach 1:
The needle can be curved in multiple directions by compressing the spring at different positions and orientations. This three-dimensional curvature capability allows a single needle insertion to access and treat the entire irregular lesion volume, eliminating the need for multiple trajectory insertions and significantly reducing procedural time
3Reliability
If a straight path is used to access lesions, then the procedure is simpler, but critical structures may be damaged
Solution Approach 1:
The spring is pre-compressed before needle insertion, storing elastic potential energy. During insertion, the spring gradually releases this energy, slowly curving the needle tip away from critical structures. This preliminary action allows the needle to navigate around sensitive areas without requiring complex real-time control mechanisms
Solution Approach 2:
The spring acts as an intermediary mechanism between the operator and the needle tip. Instead of directly controlling the needle's complex curved path, the operator simply compresses the spring, and the spring's elastic properties mediate the curvature, simplifying the control while enhancing safety
4Manufacturing precision
If additional laser trajectories are placed for incomplete ablation, then complete ablation is achieved, but surgical risk increases
Solution Approach 1:
The spring-loaded curving mechanism allows the needle to be repositioned and recurved within the same insertion site. If incomplete ablation occurs, the needle can be dynamically adjusted to target remaining lesion portions without requiring additional puncture sites, thereby maintaining ablation completeness while minimizing surgical risk
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
The steerable guide enhances ablation efficiency by achieving greater total ablation volume, accessing previously unreachable tumors, and allowing quick touch-ups without increasing surgical risk, while minimizing damage to surrounding tissue.
Implementation Method 1
a spring housing with a proximal end and a distal end, wherein the spring housing is within the shaft cavity, wherein the spring housing comprises a spring cavity and a spring within the spring cavity
Implementation Method 2
the spring is positioned, within the spring cavity, between the proximal end of the spring housing and the distal end of the translational screw, such that, when the translational screw moves in the proximal direction while a position of the spring housing is fixed, the spring is compressed between the proximal end of the spring housing and the distal end of the translational screw
Implementation Method 3
deployment of a laser fiber along a controlled curved trajectory with micro-adjustability, utilizing a nitinol wire and spring mechanism to curve the needle within a rigid outer tube
Data Source
AI summary
A steerable guide. In an embodiment, the steerable guide comprises a needle, a shaft, a spring housing, and a translational screw. The needle comprises a wire tube and a wire configured to curve the needle when retracted relative to the wire tube. The wire tube is connected to the distal end of the shaft, and the wire is connected to the distal end of the spring housing. The screw extends into a cavity within the shaft, and is configured to move along a longitudinal axis. A spring is positioned within the cavity, between the proximal end of the spring housing and the distal end of the screw. Thus, when the screw moves in the proximal direction while a position of the spring housing is fixed by the wire, the spring is compressed between the proximal end of the spring housing and the distal end of the translational screw.