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 ultrasonography. 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 hypointensity in T₁WI and hyperintensity 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 guide the surgery. Compared to ultrasonography, DW-MRN has certain advantages in resolution, field size and visualization of images. (authors)