Application of diffusion-weighted MR neurography in nontraumatic upper limb nerve torsion

Objective To investigate the diffusion weighted MR neurography(DW-MRN) features of nontraumatic upper limb nerve torsion and evaluate the application value of DW-MRN. Methods Six patients (unilateral upper extremity) who underwent surgical treatment for nerve fascicle torsion were analyzed retrospectively. Spin echo T1WI, spin echo fat suppress T2WI, DW-MRN and ultrasound were performed in all 6 patients. The DW-MRN features were analyzed by two radiologists and compared with the clinical surgeries and the results of ultrasonagraphy. Results Six patients were accurately diagnosed preoperatively by using DW-MRN as having nerve fascicle torsions. Nineteen nerve torsions were found in DW-MRN and the result was consistent with the findings at surgery, sixteen nerve torsions were found in ultrasonography, but three were missed. The affected segmental nerve fascicles showed hypointensitity in T1WI and hyperintensitity in T2WI because of nerve fascicle edema. The lesion of nerve torsion was hypointense signal, and single or multi-segmental hourglass-like change was seen at DW-MRN. Conclusions The DW-MRN of nontraumatic upper limb nerve torsion has certain characteristics, and can display the location and number of nerve torsion clearly. DW-MRN features is helpful in the diagnosis, differential diagnosis of nontraumatic upper limb nerve torsion and guidethesurgery. Compared to ultrasonography, DW-MRN has certain advantages in resolution, field size and visualization of images. Key words: Radial nerve; Median nerve; Magnetic resonance imaging