MR Neurography: Current Several Issues for Novice Radiologists

Diffusion-Weighted MR Neurography with Unidirectional Motion-Probing Gradient to Evaluate Lumbar Nerve Roots at 1.5T MR

Purpose

Recent studies have demonstrated the usefulness of diffusion-weighted MR neurography (DW MRN) for assessing nerve roots. This study aimed to evaluate the utility of DW MRN with a unidirectional motion-probing gradient (MPG) for the lumbar nerve roots at 1.5T MR.

Materials and Methods

Sixty-four lumbar spine MRI scans with DW MRN using anteroposterior unidirectional MPG were retrospectively analyzed. Any changes in the 512 lumbar spinal nerve roots from L3 to S1 were evaluated using T2-weighted imaging (T2WI), contrast-enhanced T1-weighted imaging (CE T1WI), and DW MRN, with agreement and correlation analysis.

Results

T2WI revealed compression of 78 nerve roots, and CE T1WI revealed 52 instances of nerve root enhancement. Sixty-seven nerve roots showed swelling and hyperintensity on DW MRN. A total of 42 nerve roots showed changes in the CE T1WI and DW MRN sequences. Moderate to substantial agreement and moderate positive correlation were observed between DW MRN and CE T1WI, as well as DW MRN and T2WI (κ = 0.59-0.65, ρ = 0.600-0.653).

Conclusion

DW MRN with unidirectional anteroposterior MPG can help evaluate neuritis-related changes in spinal nerve roots and could serve as a sequence capable of complementing or substituting gadolinium CE imaging.

3.0-Tesla MRI of normal canine adrenal glands

Adrenal disease is a common problem in dogs and MRI is increasingly being used as an adjunctive diagnostic test. To date, the MRI features of normal canine adrenal glands have only been reported using 1.5-Tesla (T) MRI. The aims of this prospective, methods-comparison, exploratory study were to evaluate the effects of pulse sequence on the appearance of normal canine adrenal glands using 3 Tesla MRI. Six research beagle dogs were sampled and the following pulse sequences were acquired for each: (1) T2-weighted images using two-dimensional (2D) turbo spin-echo (TSE), single-shot spin-echo (SSTSE), and three-dimensional (3D) TSE, (2) T1-weighted images using 2D TSE, 3D TSE, and 3D turbo field echo sequences, (3) post-contrast T1-weighted images, and (4) chemical shift imaging. The signal-to-noise ratio and contrast-to-noise ratio were measured for each dog and each pulse sequence. The signal intensity, clarity of the contour, distinction of the corticomedullary junction, degrees of motion, partial volume, and chemical shift artifact, and homogeneity of the contrast enhancement were evaluated qualitatively. In all sequences, except for chemical shift imaging, the adrenal glands were visualized in both planes with successful control of motion artifacts by manual ventilation. The adrenal contour was considered to be most clearly visualized with 2D TSE. Adrenal images were acquired within the shortest time using SSTSE although the contour was less clearly visualized than with TSE. Findings from this study in normal dogs can serve as background for further 3.0-T MRI studies of dogs with adrenal disease.