The optimal visualization of brachial plexus with utilization of nerve-sheath signal increased with inked rest-tissue rapid acquisition of relaxation imaging MR neurography and initial dignostic application

Abstract

Objective To assess the optimal visiualization capacity of brachial plexus with three-dimensional nerve-sheath signal increased with inked rest-tissue rapid acquisition of relaxation imaging (3D SHINKEI), exploring the feasibility of preliminary diagnostic value on brachial plexus diseases. Methods MRI scans were performed on 24 healthy volunteers with no history of brachial plexus injury, and 46 patients whose outcomes of lesions had been verified as post-ganglionic brachial plexus injuries by surgery or clinical follows-up . The scan series consist 3D SHINKEI, STIR in the coronal plane as well as DW-MRN in the axial plane using a 3.0 T MR system. The source and post-processed images of 3D SHINKEI and DW-MRN were scored according to the optimal visibility on brachial plexus, in the meanwhile, contrast-to-noise ratio of the original images in the 3D SHINKEI and STIR sequences were calculated separately. Two radiologists blindly compared the detection rate of positive brachial plexus injuries between 3D SHINKEI and STIR in 46 patients. And then analyze the outcomes by means of Kappa test, Mann-Whitney test , independent sample t test, and Chi-square test. Results Post-ganglionic brachial plexus showed high intensity in the 3D SHINKEI sequence. In the 24 healthy volunteers, the scores by the two radiologists were 3.6 ± 0.6, 3.5 ± 0.6, 3.0 ± 0.2, 2.9 ± 0.1, respectively. There was statistical difference between the two sequences (Z=2.667,P=0.008,P<0.05). And the Kappa was 0.8 and 0.6 with favorable consistency. The CNR of 3D SHINKEI and STIR were 0.61±0.07, 0.42±0.03 (t=12.78, P=0.001, P<0.05). The positive detection rates of post-ganglionic brachial plexus injuries on 3D SKINKEI and STIR were, 78.3%, 52.2% (χ2=9.421, P<0.05). Conclusions 3D SHINKEI sequence demonstrates robust visibility consistently and can clearly display the structures and signals of post-ganglionic abnormality, compared with DW-MRN and STIR. This technique can be helpful to provide more complementary information to further confirm the diagnosis of brachial plexus injuries. Key words: Brachial plexus neuropathies; Magnetic resonance imaging