Diagnosis of lumbar disc herniation by three-dimensional MRI

Abstract

The lumbo-sacral region has anatomical lordosis and two-dimensional magnetic resonance imaging (2D-MRI) cannot therefore show spinal roots including the dorsal root ganglions in one picture. This makes it difficult to present the lateral part of spinal root lesions. We have recently described a new three-dimensional magnetic resonance imaging (3D-MRI) method which allows a stereoscopic view of the spinal cord and spinal nerve roots. In the present study, we evaluated three 3D-MRI techniques, rapid imaging spin echo (RISE) small tip angle gradient echo (STAGE), and short TI inversion recovery (STIR), for detecting disc tissue degeneration, and spinal cord and nerve root compression for identification of nerve roots and detecting signal changes indicative of thickening of the nerve root, and for evaluation of the extent of herniation in 30 patients with lumbar disc herniation. The RISE method was superior for detecting signal changes in disc degeneration, (in 100% of patients) compared with the STAGE method (in 56.1% of patients). All methods poorly identified L4 roots compared with L5 or S1 roots. The STIR method was the best for identifying nerve roots (L4, 62.5%; L5, 87.5%; S1, 91.7%). STAGE and STIR were useful for detecting injuries of the nerve roots. RISE showed disc extrusion better than the other techniques (in 64.7% of patients). The presurgical diagnosis on 3D-MRI agreed with the pathology findings at surgery in 71.4% of STIR, 55.6% of RISE, and 33.3% of STAGE MR images. Our results indicate that 3D-MRI is most useful for the diagnosis of lumbar disc herniation and spinal cord and nerve root compression. The STIR method is best for identifying abnormalities of the spinal cord, roots, and intervertebral discs.