Delayed Post-traumatic Vertebral Collapse: MR Categorization and MR-Pathology Correlation

STUDY DESIGN: A retrospective study. PURPOSE: To categorize the MR appearance of ischemic vertebral collapse and to correlate surgical and histologic findings. OVERVIEW OF LITERATURE: X-ray and MRI findings of delayed posttraumatic vertebral collapse shows several patterns. Histopathologic signs of osteonecrosis were present only in minor portion of cases sampled for biopsy of delayed post-traumatic vertebral collapse in the literature. METHODS: Twenty-one patients (22 vertebral bodies), with surgically and histopathologically proven ischemic vertebral collapse were included. The patients were examined with a 1.5 T MR imager. Spin echo T1- and T2-weighted images were obtained in axial and sagittal planes. Two experienced musculoskeletal radiologists, who reached consensus, evaluated the MR images. Then, MR-pathology correlations were made. RESULTS: Four different MR patterns were identified. Fluid patterns, were seen in 14% (3/22) of the affected vertebral bodies, and were characterized by hypo-intense signals on T1-weighted images, and hyper-intense signals, similar to water, on T2-weighted images. Extensive bone necrosis was predominant. Compression pattern, the most common pattern, found in 41% (9/22 vertebral bodies), was characterized by a marked decrease of anterior column height. Bone necrosis, granulation tissue, marrow fibrosis, and reactive new bone formation were found in relatively equal proportion. Granulation pattern, seen in 27% (6/22 vertebral bodies), was characterized by hypo-intense signals on T1-weighted images, and intermediate signals on T2-weighted images. Extensive granulation tissue was predominant. Mixed patterns were present in 18% (4/22), of the vertebral bodies. CONCLUSIONS: Awareness of histopathologic correlation of MR patterns in patients with delayed post-traumatic vertebral collapse may facilitate effective interpretation of clinical MR images of the spine.