Contrast enhancement pattern and frequency of previously unoperated lumbar discs on MRI

Enhancement frequency and patterns (linear intradiscal, nodular intradiscal, and peridiscal) of the 210 previously unoperated lumbar discs were evaluated using contrast-enhanced lumbar MRI. They also were compared with morphologic abnormalities (normal, bulging, protruded, and extruded) and signal alteration (high signal on T2-weighted images) of the disc. Image interpretation was decided by the consensus of two musculoskeletal radiologists. Enhancement was observed in 69 (32.6%) discs. The enhancement patterns were either intradiscal, linear of (79.7%) or nodular (10.2%), peridiscal (7.2%), or combined (2.9%). Thirty-five (77.8%) of the 45 herniated discs, 35 (77.8%) were enhanced, whereas 34 (20.6%) of 165 normal- appearing discs were enhanced. Enhancement was observed more frequently in discs with high signal intensity zones (P < 0.05). In the six patients with enhanced discs, surgery revealed granulation tissue in three extruded discs, two protruded discs, and one bulging disc. The authors believe that contrast enhancements are frequent in herniated discs and are not infrequent in normal-appearing discs. The understanding of various enhancement patterns may help in the interpretation of lumbar spine MRI.