SHINKEI--a novel 3D isotropic MR neurography technique: technical advantages over 3DIRTSE-based imaging.

OBJECTIVES: Technical assessment of SHINKEI pulse sequence and conventional 3DIRTSE for LS plexus MR neurography.

METHODS: Twenty-one MR neurography examinations of the LS plexus were performed at 3 T, using 1.5-mm isotropic 3DIRTSE and SHINKEI sequences. Images were evaluated for motion and pulsation artefacts, nerve signal-to-noise ratio, contrast-to-noise ratio, nerve-to-fat ratio, muscle-to-fat ratio, fat suppression homogeneity and depiction of LS plexus branches. Paired Student t test was used to assess differences in nerve conspicuity (p < 0.05 was considered statistically significant). ICC correlation was obtained for intraobserver performance.

RESULTS: Four examinations were excluded due to prior spine surgery. Bowel motion artefacts, pulsation artefacts, heterogeneous fat saturation and patient motion were seen in 16/17, 0/17, 17/17, 2/17 on 3DIRTSE and 0/17, 0/17, 0/17, 1/17 on SHINKEI. SHINKEI performed better (p < 0.01) for nerve signal-to-noise, contrast-to-noise, nerve-to-fat and muscle-to-fat ratios. 3DIRTSE and SHINKEI showed all LS plexus nerve roots, sciatic and femoral nerves. Smaller branches including obturator, lateral femoral cutaneous and iliohypogastric nerves were seen in 10/17, 5/17, 1/17 on 3DIRTSE and 17/17, 16/17, 7/17 on SHINKEI. Intraobserver reliability was excellent.

CONCLUSION: SHINKEI MRN demonstrates homogeneous and superior fat suppression with increased nerve signal- and contrast-to-noise ratios resulting in better conspicuity of smaller LS plexus branches.

KEY POINTS: • SHINKEI provides homogeneous and superior fat suppression, shown by higher nerve and muscle-to-fat ratios. • SHINKEI shows better nerve signal-to-noise and contrast-to-noise ratios than 3DIRTSE. • SHINKEI enables nerve-selective images with increased conspicuity of smaller LS plexus branches. • SHINKEI should be considered in routine MR neurography of the LS plexus.