# Fast Calculation Method of Average g-Factor for Wave-CAIPI Imaging

## TL;DR

This paper introduces a rapid calculation method for the average g-factor in Wave-CAIPI MRI, significantly reducing computation time while maintaining accuracy, thereby facilitating more efficient imaging parameter optimization.

## Contribution

A novel fast approximation technique for average g-factor calculation in Wave-CAIPI MRI using Taylor linear approximation, greatly speeding up the process.

## Key findings

- The proposed method is about 1000 times faster than traditional theoretical calculations.
- It is approximately 1700 times faster than the pseudo multiple replica method.
- The accuracy of the approximation is consistent with existing methods.

## Abstract

Wave-CAIPI MR imaging is a 3D imaging technique which can uniformize the g-factor maps and significantly reduce g-factor penalty at high acceleration factors. But it is time-consuming to calculate the average g-factor penalty for optimizing the parameters of Wave-CAIPI. In this paper, we propose a novel fast calculation method to calculate the average g-factor in Wave-CAIPI imaging. Wherein, the g-factor value in the arbitrary (e.g. the central) position is separately calculated and then approximated to the average g-factor using Taylor linear approximation. The verification experiments have demonstrated that the average g-factors of Wave-CAIPI imaging which are calculated by the proposed method is consistent with the previous time-consuming theoretical calculation method and the conventional pseudo multiple replica method. Comparison experiments show that the proposed method is averagely about 1000 times faster than the previous theoretical calculation method and about 1700 times faster than the conventional pseudo multiple replica method.

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Source: https://tomesphere.com/paper/1903.01731