Usefulness of Dynamic Contrast Enhanced Lumbar Spine MR Imaging in Postoperative Herniated Lumbar Disc

Nam, Ji Eun; Chung, Tae Sub; Kim, Young Soo; Cho, Yong Eun; Park, Mi Suk

Abstract

PURPOSE: To compare the usefulness of dynamic contrast enhanced lumber spine MR Imaging with that ofconventional delayed contrast enhanced MR imaging in the assessment of postoperative herniated lumbar disc. MATERIALS AND METHODS: Forty-one postoperative herniated lumbar disc (HLD) lesions of 32 patients with back painwere examined with MR imaging(1.5T, Vision, Siemens, Germany). Five-phase dynamic 2D FLASH sagittalimages(TR/TE=118.1 msec) was obtained every 19 seconds with a 4 minutes delayed image after contrast injection. Asseen on delayed images, the discs were assessed as recurred, fibrosis, or no change. On dynamic images, thepattern of enhancement was evaluated as follows : Type I(no change in peripheral disc enhancement between theearly and late phase);or Type II(minimal internal extension of marginal smooth enhancement during the latephase);or Type III(marked internal extension f peripheral irregular enhancement). Dynamic and delayed imaging werecompared, and early epidural space enhancement with rapid wash-out was also evaluated. RESULTS: of 41postoperative HLDs, 39 lesions showed peripheral contrast enhancement. Evaluation depended on delayed imaging, andwas as follows:recurred HLD(n=27);fibrosis(n=5);no change in postoperative disc(n=7). On dynamic contrast-enhancedimaging, enhancement patterns were Type I(n=29), Type II(n=7), and Type III(n=3). In 29 Type-I lesions, there wereno significant differences in image findings between dynamic and delayed images. However, in the lesions(typeII:n=7, type III:n=3), findings additional to those revealed by delayed images were demonstrated by dynamiccontrast-enhanced MR imaging. Nine of the ten Type-II and III lesions were diagnosed as recurred HLD. On dynamicOn dynamic images, five lesions showed early epidural space enhancement. CONCLUSION: dymamic contrast-enhancedlumbar spine MR imaging provided additional findings such as increased peripheral disc enhancement, and epiduralspace enhancement, which cannot be detected on conventional delayed images. Inrecurred postoperative herniatedlumbar discs, these findings are frequent.