Morphologic analysis of normal human lumbar dorsal root ganglion by 3D MR imaging.

BACKGROUND AND PURPOSE The dorsal root ganglion (DRG) of the spinal nerve has been considered a key structure in the mechanism of low-back pain and radicular symptoms. The purpose of this study was to clarify the normal morphologic features and variations of the lumbar DRGs in a healthy population by using 3D MR imaging. METHODS 3D fast-field echo (FFE) with water selective excitation coronal MR images of lumbar spine obtained in 115 healthy volunteers were further reconstructed into a radial stack of 15 coronal images by using maximum intensity projection technique. The DRGs from L1 through L5 were assessed for the location, signal intensity, architecture, and dimensions. RESULTS Most DGRs were foraminal in location. Only 5.7% of the L5 DGRs were located intraspinally. The sizes of L1, L2, and L5 DRGs in men were larger than those in women (P < .05). The dimensions of the DRGs gradually increased from L1 to L5 (P < .0001). The biganglia (2 ganglial components) frequently occurred in the L4 and L3 DRGs, whereas the singular ganglion (1 ganglial component), in the L5 and L1 DRGs. CONCLUSION The normal anatomy and variants of the lumbar DRG could be better demonstrated by 3D MR imaging with water selective excitation technique. The relatively larger and more proximally located DRGs in the lower lumbar region may be more susceptible to compression. An appreciation of normal anatomy and variants of DRGs radiologically is helpful for the diagnosis and proper treatment for radiculopathy.