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 (κ = 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.