title: Delayed Post-traumatic Vertebral Collapse: MR Categorization and MR-Pathology Correlation.
abstract: METHODS
  A retrospective study.
  
  
  OBJECTIVE
  To categorize the MR appearance of ischemic vertebral collapse and to correlate surgical and histologic findings.
  
  
  BACKGROUND
  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.
authors.affiliation: Department of Orthopedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Chong Suh
authors.initials: CS
authors.lastname: Lee
authors.forename: Je-Wook
authors.initials: JW
authors.lastname: Yu
authors.forename: Sung Soo
authors.initials: SS
authors.lastname: Chung
authors.forename: Yeon-Lim
authors.initials: YL
authors.lastname: Suh
authors.forename: Geunghwan
authors.initials: G
authors.lastname: Ahn
authors.forename: Joong Mo
authors.initials: JM
authors.lastname: Ahn
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