Radiologic Findings of Ossified Posterior Longitudinal Ligament in the Cervical Spine

ABSTRACT

PURPOSE: To evaluate MR imaging findings of ossified posterior longitudinal ligament(OPLL) in the cervicalspine. MATERIALS AND METHODS: Retrospectively, simple radiography(n=34), CT(n=9), and MRI(n=11) of 34 patients with OPLL were reviewed. We evaluated the number of involved vertebral segment, morphologic type of lesions onaxial and sagittal imaging, spinal canal narrowing on the involved intervertebral disk level, intervertebral for aminal narrowing, relationship between spinal cord compression and morphologic type, and signal intensity onMRI. RESULTS: Average number of involved vertebral segment was 2.65(90/34). Most commonly involved vertebrallevel was C3--C4. On sagittal image, the lesions were classified to be continuous type(n=15), segmental type(n=7),mixed type(n=4), and circumscribed type(n=7). The most common type was continuous one(42%). On axial image, the lesions were classified to square type(n=13), mushroom type(n=18), hill type(n=13). The most common type was mushroom one(41%). Forty-five percent(20/44) showed spinal stenosis which exceeded 25% of anteroposterior diameter of spinal canal. Twenty-three percent(19/81) of the case showed intervertebral foraminal narrowing. T1- and T2-weighted MRI showed low signal intensity in every 11 case. Two cases showed focal high signal intensity within lowsinal intensity lesion on T1 weighted images. CONCLUSIONS: The ossified lesion of OPLL could be evaluated with simple radiography and CT. MRI displayed spinal cord compresion, intervertebral foraminal narrowing, and associated vertebral disease which maybe useful in preoperative evaluation of symptomatic patients.