Carpal tunnel syndrome:: assessment by turbo spin echo, spin echo, and magnetization transfer imaging applied in a low-field MR system

Purpose: The purpose of this work was to evaluate patients with carpal tunnel syndrome (CTS) using a low-field extremity MR system (E-MRI; 0.2 T). Method: Twenty-two patients with typical findings of CTS and 30 control persons were imaged on an E-MRI, Axial T2-weighted turbo SE (TSE), T1-weighted SE sequences, and 2D GRE magnetization transfer (MTC) sequences were compared. SE and MTC sequences were obtained before and after contrast agent administration (0.1 mmol/kg body wt of Gd-DTPA). Two readers evaluated typical MR findings of CTS independently. Results: Patients with CTS demonstrated palmar bowing of the flexor retinaculum significantly more often. The normal or edematous median nerve was best identified on TSE and MTC scans (kappa = 0.59 and 0.8). The MTC sequences showed perineural enhancement significantly better than respective T1-weighted SE sequences but were rated second in comparison with T2-weighted TSE scans. Conclusion: At low-field strength, median nerve edema is best depicted on T2-weighted TSE sequences, whereas MTC sequences are most sensitive to perineural contrast enhancement.