Water T2 Mapping in Fatty Infiltrated Thigh Muscles of Patients With Neuromuscular Diseases Using a T2 -Prepared 3D Turbo Spin Echo With SPAIR.

Abstract

Muscle water T2 (T2w ) has been proposed as a biomarker to monitor disease activity and therapy effectiveness in patients with neuromuscular diseases (NMD). Multi-echo spin-echo (MESE) is known to be affected by fatty infiltration. A T2 -prepared 3D turbo spin echo (TSE) is an alternative method for T2 mapping, but has been only applied in healthy muscles. To examine the performance of T2 -prepared 3D TSE in combination with spectral adiabatic inversion recovery (SPAIR) in measuring T2w in fatty infiltrated muscles based on simulations and in vivo measurements in thigh muscles of patients with NMD. Prospective. One healthy volunteer, 34 NMD patients. T2 -prepared stimulated echo acquisition mode (STEAM) magnetic resonance spectroscopy (MRS), SPAIR STEAM MRS, and SPAIR T2 -prepared STEAM MRS were performed in the subcutaneous fat of a healthy volunteer's thigh. T2 mapping based on SPAIR 2D MESE and SPAIR T2 -prepared 3D TSE was performed in the NMD patients' thigh region. Multi-TE STEAM MRS was performed for measuring a reference T2w at different thigh locations. The behavior of the fat spectrum in the SPAIR T2 -prepared 3D TSE was simulated using Bloch simulations. The in vivo T2 results of the imaging methods were compared to the in vivo T2w MRS results. Pearson correlation coefficient with slope and intercept, relative error. The simulated T2 for the SPAIR T2 -prepared 3D TSE sequence remained constant within a relative error of not more than 4% up to a fat fraction of 80%. In vivo T2 values of SPAIR T2 -prepared 3D TSE were in good agreement with the T2w values of STEAM MRS (R = 0.86; slope = 1.12; intercept = -1.41 ms). In vivo T2 values of SPAIR 2D MESE showed large deviations from the T2w values of STEAM MRS (R = 0.14; slope = 0.32; intercept = 38.83 ms). The proposed SPAIR T2 -prepared 3D TSE shows reduced sensitivity to fatty infiltration for T2w mapping in the thigh muscles of NMD patients. 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2020;51:1727-1736.