Is fat suppression in T1 and T2 FSE with mDixon superior to the frequency selection-based SPAIR technique in musculoskeletal tumor imaging?

OBJECTIVE

To determine the image quality of fast spin echo (FSE) with mDixon relative to spectral attenuated inversion recovery (SPAIR) FSE sequences in musculoskeletal tumor imaging on a 1.5-T MRI system.

MATERIALS AND METHODS

In a HIPAA-compliant prospective study, 265 patients requiring musculoskeletal tumor MRI scans were included. Patient consent was waived by the medical ethical committee. Two radiologists compared SPAIR and mDixon FSE water-only images in both T2- and T1-weighted gadolinium-enhanced (T1-Gd) sequences using a five-point scale (paired samples t test and visual grading characteristics curves (VGC)). Homogeneity of fat suppression, noise, contrast, several artifacts (motion, phase, edge blurring and water-fat swap) and subjective preference were evaluated.

RESULTS

Readers did not have subjective preference for either sequence in 71% and 55% (reader 1 and 2, respectively). Scores for homogeneous fat suppression were significantly (p < 0.01) higher for mDixon (4.88 in T2 and 4.87 in T1-Gd) than for SPAIR (4.31 for T2 and 4.21 for T1-Gd). All VGC curves for homogeneity demonstrated preference for mDixon. In 57 individual mDixon cases, fat-suppression homogeneity was strikingly better (≥ 2 points higher), namely in areas with field heterogeneity. Average noise and contrast scores were slightly higher for mDixon, as were motion artifact scores for SPAIR (< 0.5 points difference).

CONCLUSIONS

mDixon fat suppression was significantly more homogeneous than SPAIR on both T2 and T1-Gd FSE images in musculoskeletal tumor protocols. In areas of field inhomogeneity, mDixon outperforms SPAIR. SPAIR had slightly less motion artifacts than mDixon.