# Spiral Blurring Correction with Water-Fat Separation for Magnetic Resonance Fingerprinting in the Breast

## TL;DR

This paper presents a method to correct spiral blurring artifacts in Magnetic Resonance Fingerprinting (MRF) for breast imaging, improving the accuracy of tissue relaxation time measurements by combining water-fat separation with conjugate phase reconstruction.

## Contribution

The study introduces a novel correction technique for spiral MRF that integrates 3-point Dixon water-fat separation with conjugate phase reconstruction, enhancing quantitative mapping accuracy.

## Key findings

- Blurring correction reduced NRMSE from 16% to 8% for T1 in phantom experiments.
- Correction decreased NRMSE from 18% to 11% for T2 in phantom experiments.
- In-vivo, the method removed fat bias from breast tissue measurements.

## Abstract

PURPOSE: Magnetic Resonance Fingerprinting (MRF) with spiral readout enables rapid quantification of tissue relaxation times. However, it is prone to blurring due to off-resonance effects. Hence, fat blurring into adjacent regions might prevent identification of small tumors by their quantitative T1 and T2 values. This study aims to correct for the blurring artifacts, thereby enabling fast quantitative mapping in the female breast. METHODS: The impact of fat blurring on spiral MRF results was first assessed by simulations. Then, MRF was combined with 3-point Dixon water-fat separation and spiral blurring correction based on conjugate phase reconstruction. The approach was assessed in phantom experiments and compared to Cartesian reference measurements, namely inversion recovery (IR), multi-echo spin echo (MESE) and Cartesian MRF, by normalized root mean square error (NRMSE) and standard deviation (STD) calculations. Feasibility is further demonstrated in-vivo for quantitative breast measurements of 6 healthy female volunteers, age range 24-31 years. RESULTS: In the phantom experiment, the blurring correction reduced the NRMSE per phantom vial on average from 16% to 8% for T1 and from 18% to 11% for T2 when comparing spiral MRF to IR/MESE sequences. When comparing to Cartesian MRF, the NRMSE reduced from 15% to 8% for T1 and from 12% to 7% for T2. Furthermore, STDs decreased. In-vivo, the blurring correction removed fat bias on T1/T2 from a rim of about 7-8 mm width adjacent to fatty structures. CONCLUSION: The blurring correction for spiral MRF yields improved quantitative maps in the presence of water and fat.

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Source: https://tomesphere.com/paper/1905.03558