Comparison of standard, prone and cine MRI in the evaluation of tethered cord

Abstract

Background: Tethered cord syndrome (TCS) is defined by abnormal traction on the spinal cord that confines its movement. Surgical cord release usually stops neurological deterioration; therefore, early and accurate neuroradiological diagnosis is important. Supine MRI is the imaging modality of choice, but prone MRI and cine MRI can demonstrate cord movement.

Objective: We compared the diagnostic accuracies of standard MRI, prone MRI and cine MRI in patients with clinical suspicion of TCS and evaluated inter-reader reliability for MR imaging.

Materials and methods: Children who underwent MRI for suspicion of TCS were retrospectively identified. Supine, prone and cine MRI studies were re-read by two pediatric neuroradiologists. Conus level, filum appearance and cord movement were documented.

Results: Thirteen of 49 children had tethered cord documented at surgery. Conus level had the highest diagnostic accuracy (sensitivity 69-77%, specificity 94%, positive predictive value 82-83%, negative predictive value 89-92%, correct diagnosis 88-90%) and highest between-reader concordance (98%). Prone and cine MRI did not add to the accuracy of the supine imaging.

Conclusion: Conus level provides the highest diagnostic accuracy and inter-reader reliability in TCS. Until a larger series is evaluated, it remains questionable whether prone or cine MRI provides enough additional diagnostic information to warrant routine use.