Value of MR diffusion weighted neurography in median nerve and ulnar nerve

Abstract

Objective To evaluate the feasibility and clinical value of diffusion weighted MR neurograph(DW-MRN) in the median nerve and ulnar nerve at the wrist and palm.Methods Forty two healthy volunteers and 7 patients whose electromyography indicated the median or ulnar nerve injury underwent fat suppression proton density-weighted imaging(FS-PDWI) and DW-MRN imaging.The certainty of identifying the nerves at the wrist and palm were analyzed by 2 experienced neuroradiologists independently using a four-point grading scale on the basis of shape of nerve depiction and the signal intensity.Interobserver agreement for visualization scores was calculated using the Kappa statistic.The number of the trunk of median nerve and ulnar nerve,palm digitalnerve,deep and superficial branch of ulnar nerve which can be visualized in DW-MRN and FS-PDWI of 42 volunteers was compared by using Chisquare test.Two radiologists reviewed DW-MRN images in patients and analyzed the clinical value of DW-MRN.Results The mean scores of the median nerve were(4.0±0.0) and(4.0±0.0) for observers 1 and 2,respectively.Interobserver agreement was good(Kappa =1.000).The mean scores of ulnar nerve were(3.45±0.74) and(3.43±0.67) for observers 1 and 2,respectively.Interobserver agreement was good(Kappa =0.793).The numbers of visualized trunk of median nerve and ulnar nerve,palm digitalnerve,deep and superficial branch of ulnar nerve were 42,42,42,42,42,38,37 on DW-MRN and 42,39,27,28,25,17,21 on FS-PDWI sequence.The percentage of visualized palm digital nerve,deep and superficial branch of ulnar nerve on DW-MRN were higher than those on FS-PDWI sequence(x2value were18.26,16.80,21.31,23.23,14.26,P＜0.05).The extent of lesions and the relationship with nerves were displayed clearly on DW-MRN images of 7 patients.Conclusion DW-MRN can provide a three dimensional visualization of the median nerve and ulnar nerve at the wrist and palm and can display the extent of the lesions and the relationship with nerves in patients clearly. Key words: Median nerve; Ulnar nerve; Magnetic resonance imaging