Dynamic lumbosacral MRI compared to upright myelography: Comparison in the detection of segmental dural compression

Purpose: The purpose of this study was to determine the accuracy of dynamic lumbosacral-MRI compared to upright myelography to detect segmental dural compression. Methods and Materials: 95 patients were screened for the study. Seventeen patients complaining of low back pain and clinically suspected dural compression qualified for the study. These patients underwent myelography and dynamic lumbosacral-MRI with an open-configuration 0.25 T tilting system. Images were obtained in supine and upright position for both modalities. Two independent readers evaluated the myelography images and the lumbosacral- MRI on a persegment basis with regard to segmental dural compression. Reference standard was a consensus reading of myelography in upright position. Reader agreement was assessed by correlation statistics (Cohen's kappa) and diagnostic accuracy was calculated on a persegment basis. Results: Myelography in upright position showed 35 segmental dural compressions. Lumbosacral-MRI showed 30 segmental dural compressions in supine and 33 in upright position. The agreement between the readers for Myelography in supine and upright position was 0.881 and 0.808 respectively. The inter-rater agreement for MRI in supine and upright position was 0.895 and 0.747. MRI sensitivity/specificity in upright position were 80%/92% for reader 1 and 74.3%/96% for reader 2; in supine position 77.1%/96% for reader 1 and 74.1%/98% for reader 2. Conclusion: Dynamic MRI with an open-configuration, low-field tilting MRI system is a feasible and promising tool to study lumbosacral dural compression. We demonstrated that this MR technology performed highly specific compared to upright myelography, but had some limitations regarding sensitivity. Interobserver agreement was comparable to myelography.