# Fiber Optical Shape Sensing of Flexible Instruments for Endovascular Navigation

## TL;DR

This paper presents an optimized fiber Bragg grating-based shape sensing model for flexible endovascular instruments, achieving high accuracy in 3D shape reconstruction and reducing errors in minimally invasive navigation.

## Contribution

The study develops an error-minimizing shape sensing model for fiber Bragg gratings, improving accuracy in 3D shape reconstruction for endovascular navigation.

## Key findings

- Average error of 0.35 to 1.15 mm in shape sensing
- Maximum error of 0.75 to 7.53 mm over 38 cm
- Average error of 1.13 mm in realistic scenario

## Abstract

Purpose: Endovascular aortic repair procedures are currently conducted with 2D fluoroscopy imaging. Tracking systems based on fiber Bragg gratings are an emerging technology for the navigation of minimal-invasive instruments which can reduce the x-ray exposure and the used contrast agent. Shape sensing of flexible structures is challenging and includes many calculations steps which are prone to different errors. To reduce this errors, we present an optimized shape sensing model. Methods: We analyzed for every step of the shape sensing process, which errors can occur, how the error affects the shape and how it can be compensated or minimized. Experiments were done with a multicore fiber system with 38 cm sensing length and the effects of different methods and parameters were analyzed. Furthermore we compared 3D shape reconstructions with the segmented shape of the corresponding CT scans of the fiber to evaluate the accuracy of our optimized shape sensing model. Finally we tested our model in a realistic endovascular scenario by using a 3D printed vessel system created from patient data. Results: Depending on the complexity of the shape we reached an average error of 0.35 to 1.15 mm and maximal error of 0.75 to 7.53 mm over the whole 38 cm sensing length. In the endovascular scenario we obtained an average and maximal error of 1.13 mm and 2.11 mm, respectively. Conclusions: The accuracies of the 3D shape sensing model are promising and we plan to combine the shape sensing based on fiber Bragg gratings with the position and orientation of an electromagnetic sensor system to obtain the located shape of the catheter.