Posterior Element Lesions

Case A: An exophytic bone lesion arises from the left L4 transverse process and demonstrates continuity of its cortex and medullary cavity with those of the transverse process. Short T1 inversion recovery images reveal a cartilaginous cap along the superior-medial aspect of the lesion. A review of all studies and sequences also showed impingement upon the exiting left L3 nerve root, explaining the patient’s symptoms.

Case B: A lesion centered in the right L2 pars interarticularis region is calcified centrally and has a well-circumscribed radiolucent rim with surrounding bony sclerosis. It measures approximately 1.2 cm in maximal diameter. MRI shows edema within the adjacent bone marrow and inflammatory changes in the adjacent soft tissues.

Case C: A multilobulated, expansile, heterogeneously enhancing mass is centered in the left C4 pedicle and also involves the left lamina and left posterolateral vertebral body. It encases and narrows the left vertebral artery and extends into the left extradural spinal canal, effacing the thecal sac. No matrix is perceptible. T2-weighted MRI demonstrates multiple fluid-fluid levels within the mass.

Case D: An expansile lytic lesion is centered in the left pedicle of the C5 vertebra, extending laterally into the articular mass and measuring approximately 1.6 cm in maximal diameter. Several small central calcifications are noted, along with adjacent bony sclerosis. T2-weighted images (not shown) and contrast-enhanced MRI demonstrate extensive reactive inflammatory changes in the adjacent bone and soft tissues. There is avid FDG uptake on the bone scan.