MRI-Guided Frame With Rotatable Yoke and Targeting Cannula
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Solution Overview
Problem
Current MRI-guided surgery systems lack efficient methods for accurately positioning and delivering diagnostic or therapeutic devices within the body, particularly in procedures involving bone drilling, such as skull surgeries, due to limitations in precision and maneuverability.
Innovation Solution
An MRI-guided interventional system featuring a frame with a removable targeting cannula and user-activatable actuators that allow for precise positioning and rotation, equipped with MRI-visible fiducial markers for localization, and a guide system for inserting various devices like stimulation leads, ablation probes, or drug delivery tools through a patient access aperture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a frame system with multiple actuators is used to enable precise positioning and rotation of the targeting cannula, then positioning precision and maneuverability are improved, but device complexity increases
Solution Approach 1:
The frame system is divided into multiple independently controllable segments: a base secured to the patient's body, a yoke that rotates about a roll axis, and a platform that rotates about a pitch axis. Each segment can be adjusted independently through dedicated actuators (roll actuator, pitch actuator), allowing precise positioning of the targeting cannula while maintaining manageable system complexity through modular design
Solution Approach 2:
The frame system incorporates multiple degrees of freedom with movable components. The yoke is rotatable about the roll axis, the platform is rotatable about the pitch axis, and the X-Y support table can translate in X and Y directions. This dynamic configuration allows the system to adapt to various targeting requirements while maintaining precision, resolving the contradiction between positioning capability and system complexity
2Measurement precision
If MRI-visible fiducial markers are added to the frame for localization, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The frame includes MRI-visible fiducial markers that appear as distinct signals in MRI images. These markers enable precise determination of the frame's location and orientation within the patient's body by providing reference points that can be tracked and measured in the MRI coordinate system, improving measurement precision without significantly increasing mechanical complexity
Solution Approach 2:
The fiducial markers serve as intermediary elements between the physical frame and the MRI imaging system. They provide a bridge that allows the MRI scanner to accurately locate and track the frame position, enabling precise measurement and navigation without requiring complex integrated sensors or electronics in the frame itself
3Manufacturing precision
If a removable targeting cannula with guide bore is used to guide device placement, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The targeting cannula with its precisely manufactured guide bore is positioned and secured to the frame before the actual device insertion procedure. This preliminary positioning establishes an accurate trajectory path, ensuring that subsequent device placements follow the pre-determined precise path. The cannula acts as a pre-positioned guide that simplifies the insertion process while maintaining high manufacturing precision
Solution Approach 2:
The targeting cannula serves as an intermediary tool between the frame system and the final interventional device. It provides a pre-formed guide bore that directs the device along the desired trajectory, separating the complex positioning function (performed by the frame and actuators) from the insertion function (performed by the cannula), thereby improving precision while managing overall system complexity
4Measurement precision
If multiple actuators are used to translate and rotate the frame for positioning the targeting cannula, then positioning precision is improved, but ease of operation deteriorates
Solution Approach 1:
The frame system incorporates self-aligning and self-locking mechanisms that reduce the operator's burden. The actuators are designed with built-in positioning features that automatically maintain accurate alignment during adjustment, and locking mechanisms that secure positions without requiring additional tools or complex procedures. This self-service capability maintains high positioning precision while improving ease of operation
Solution Approach 2:
The system replaces complex manual mechanical adjustment mechanisms with more user-friendly actuator designs. The roll actuator, pitch actuator, and X-Y translation mechanisms are engineered to provide intuitive control with reduced friction and improved responsiveness, allowing operators to achieve precise positioning with simpler, more ergonomic controls that ease the operation burden
Data Source
AI summary
A trajectory frame for use with an MRI-guided interventional system includes a base having a patient access aperture formed therein. The base is configured to be secured to the body of a patient. A yoke is mounted to the base and is rotatable about a roll axis. A platform is mounted to the yoke and is rotatable about a pitch axis. An elongated guide is secured to the platform and includes opposite proximal and distal end portions and a bore that extends from the proximal end portion to the distal end portion. The guide distal end portion is positioned proximate the patient access aperture. The guide is configured to removably receive various devices therein for quick release therefrom, including a targeting cannula, drill guide and drill bit, skull fixation device and driver, and catheter guide.