Spiral blurring correction with water-fat separation for magnetic resonance fingerprinting in the breast.

Teresa Nolte,Mariya Doneva,Christiane Kuhl,Daniel Truhn,Aaldert Elevelt,Volkmar Schulz,Nicolas Gross‐Weege,Peter Koken

doi:10.1002/mrm.27994

Abstract

Magnetic resonance fingerprinting (MRF) with spiral readout enables rapid quantification of tissue relaxation times. However, it is prone to blurring because of 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. 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 SD calculations. Feasibility is further demonstrated in vivo for quantitative breast measurements of 6 healthy female volunteers, age range 24-31 y. 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, SDs decreased. In vivo, the blurring correction removed fat bias on T1 /T2 from a rim of ~7-8 mm width adjacent to fatty structures. The blurring correction for spiral MRF yields improved quantitative maps in the presence of water and fat.

Highlights

Quantitative Magnetic Resonance Imaging offers an vendor independent imaging contrast, which promises the identification and classification of lesions based on their intrinsic tissue properties[1,2]
Magnetic Resonance Fingerprinting (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

Summary

Introduction

Quantitative Magnetic Resonance Imaging (qMRI) offers an vendor independent imaging contrast, which promises the identification and classification of lesions based on their intrinsic tissue properties[1,2]. Magnetic Resonance Fingerprinting (MRF) is a fast sequence that measures several quantitative markers at a time[10,11] from an image series with varying acquisition parameters such as flip angles, repetition times and RF phases. Spiral sampling results in blurred images for off-resonant spins. This effect becomes especially important if the field of view (FOV) does contain aqueous tissues, and fat, of which the main spectral peak presents an average chemical shift of about -3.5 ppm with respect to the resonance frequency of water[15]. Keeping the fat signal in T2-weighted images (and rather not suppressing it) permitted the distinction of benign from malignant tumors in such lesions that showed enhancement during dynamic contrast enhanced MRI19

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