Ossification of the posterior longitudinal ligament: MR evaluation.

PURPOSE To investigate the MR appearance of ossification of the posterior longitudinal ligament (OPLL) of the cervical spine. MATERIALS AND METHODS A retrospective review of MR images and conventional tomograms in 147 patients. RESULTS In the sagittal plane, proton-density images identified the ossified lesions more clearly than did T1- and T2-weighted images. All axial sequences identified the lesions much frequently. T1-weighted images often showed areas of increased intensity within the lesions of the continuous and mixed type, especially within the thick lesions. Fat images by Dixon technique demonstrated same areas of increased intensity, which strongly suggested fatty marrow formation. On conventional tomograms, configurations of radiolucent areas within the lesions corresponded to areas of increased intensity on T1-weighted images. CONCLUSION Proton-density sagittal and axial images are important in establishing the diagnosis of OPLL. The areas of increased intensity on T1-weighted images and radiolucent areas suggest marrow formation.