MRI-Corrected Optical Shape Sensing for Catheter Tip Localization
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Solution Overview
Problem
Existing methods for determining the position of invasive devices using optical shape sensing in magnetic resonance imaging (MRI) suffer from inaccuracies, particularly for flexible devices like catheters, with tip localization errors exceeding 6mm and precision issues due to systematic errors and wire breakages, limiting their application in procedures like cardiac catheter ablations.
Innovation Solution
Integrate optical shape sensing with MRI to correct position determinations using MR imaging sequences that excite and read out signals in limited volumes around predefined points on the device, employing MR markers and signal suppression techniques to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical shape sensing is used to determine the position of the invasive device, then the entire shaft can be visualized, but the tip localization accuracy is insufficient (6mm error)
Solution Approach 1:
The patent combines optical shape sensing with MRI technology to create a hybrid localization system. The optical shape sensing provides continuous shaft visualization while MRI provides high-precision reference points, merging the advantages of both methods to achieve both full shaft visualization and high tip localization accuracy.
Solution Approach 2:
MR markers are introduced as intermediary objects that serve dual purposes: they are visible to both the optical shape sensing system and the MRI system. These markers act as mediators that transfer positional information between the two sensing modalities, enabling accurate correlation and correction of position data.
2Measurement precision
If MR markers are added to improve localization accuracy, then position determination precision improves, but device complexity increases
Solution Approach 1:
Instead of making the entire device complex, MR markers are placed only at specific critical locations such as the tip and intermediate points along the shaft. This local addition of functionality provides the necessary reference points for high-precision localization without requiring the entire device structure to be complicated.
Solution Approach 2:
The invasive device incorporates MR markers that combine different material properties - the markers are designed to be visible in both optical and MRI modalities, creating a composite structure that enables dual-modal sensing. This composite approach allows a single device to fulfill multiple sensing requirements.
3Measurement precision
If multiple measurement points are used along the fiber, then shape reconstruction improves, but errors accumulate from proximal to distal points
Solution Approach 1:
The system uses MRI-measured positions of distal points as feedback to correct the cumulative errors in optical shape sensing. The high-precision MRI data serves as a reference that feeds back into the optical sensing system, allowing real-time correction of the accumulated errors and maintaining measurement consistency throughout the fiber length.
Solution Approach 2:
MR markers are placed at predetermined locations along the fiber before the measurement process begins. These pre-positioned markers provide known reference points that can be used to calibrate and correct the optical shape sensing data, preventing error accumulation rather than correcting it after the fact.
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
Improves position determination accuracy to a fraction of the device diameter along its full length, reducing errors to a manageable level suitable for precise invasive procedures.
Implementation Method 1
It is based on optical sensing of the strain of individual optical cores along the compound fiber, either by fiber Bragg gratings or by Rayleigh scattering
Implementation Method 2
It is based on optical sensing of the strain of individual optical cores along the compound fiber, either by fiber Bragg gratings or by Rayleigh scattering
Implementation Method 3
a magnetic resonance imaging (MRI) system, wherein the MRI system is configured to measure the position x i , y i , z i of the point P i on the invasive device within the error margin
Data Source
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AI summary
For the field of determining the position of an invasive device (1) a solution for improving the localization of the invasive device (1) is specified. This is achieved by an arrangement and a method for determining the position of an invasive device (1), wherein an optical shape sensing system for sensing a position and/or shape of the invasive device (1) is provided, wherein the system is arranged to localize at least one point Pi on the invasive device (1) at a position xi, yi, zi, with some error margin (2Δxi, 2Δyi, 2Δzi) in a region of interest (3), localizing and reconstructing at least one point Pi on the invasive device (1) at a position xi, yi, zi, with some error margin (2Δxi, 2Δyi, 2Δzi) in a region of interest (3) by the optical shape sensing system. An MRI system is also provided for measuring the position xi, yi, zi of the point Pi on the invasive device (1) within the error margin in the region of interest at least in one spatial direction by the MRI system, wherein a signal of the magnetization in the error margin (2Δxi, 2Δyi, 2Δzi) is read out by the MRI system and a position of the invasive device (1) is determined based on the signal. The position xi, yi, zi, of the point Pi on the invasive device (1) in the region of interest (3) determined by the optical shape sensing system is corrected with the position xi, yi, zi, of the point Pi on the invasive device (1) in the region of interest (3) determined by the MRI system by a calculating system to an actual position of the point Pi on the invasive device (1).