Review Question - QID 219579

This 66-year-old female experienced a traumatic vertebral compression fracture following a mechanical fall. The presence of a horizontal linear or triangular area of hypointense (T1) or hyperintense (T2) signaling ("fluid sign") is suggestive of an osteoporotic vertebral fracture (Answer 2).

Osteoporotic vertebral fractures (OVF) are commonly encountered in the elderly, being the most common fragility fracture. Moreover, the spine is a common site for metastatic disease, estimated to account for ~40% of all bony metastasis. The diagnosis of compression fractures can be made with plain radiographs, however advanced imaging (CT, MRI) can be necessary for subtle fractures or suspected metastatic vertebral fractures (MVF) in those with a history of cancer or innocuous mechanism of injury. Multiple findings on MRI can suggest metastatic involvement, including pedicle or posterior column involvement; diffuse, homogenous hypointense signaling of the vertebral body on T1 imaging; and convexity of the posterior vertebral border. Whereas the presence of a horizontal linear or triangular area of hypointense (T1) or hyperintense (T2) signal, suggests an OVF.

Arana et al. performed a study examining the proficiency of clinicians from varying specialties (radiologists, radiation oncologists, orthopedic surgeons, and neurosurgeons) in diagnosing MVF versus non-traumatic OVFs on MRI in 203 patients. The overall interobserver agreement of the diagnosis was found to be 'fair' (kappa: 0.397) when the history of the patient was unknown, which improved to 'moderate' after a history of cancer was disclosed (kappa: 0.467), which was found to be similar across all subspecialties. In all subspecialties, the intraobserver agreement increased from 'substantial' (kappa: 0.624) to 'almost perfect' (kappa: 0.878) after the patient's history was provided. The authors close by highlighting the importance of patient history in optimizing the diagnostic capabilities of advanced imaging.

Yamamoto performed a retrospective review of 161 patients (43 with MVF, 118 with OVF), examining the utility of sagittal T1-weighted MRI in differentiating OVF vs MVF. The authors looked at four characteristics suggestive of metastasis (posterior column involvement, convexity of the posterior vertebral body, epidural infiltration, diffuse homogenous low signal intensity) and two features suggestive of OVFs (low-signal intensity band, posterior retropulsion of vertebral body). Posterior column involvement demonstrated the highest sensitivity, which made the finding, or lack thereof, useful for screening. In contrast. diffuse, homogenous low-signal intensity and convexity of the posterior border were found to be specific findings suggesting MVF. The authors conclude sagittal T1 imaging alone can provide diagnostic value and highlight the presence of posterior column involvement as the most important parameter for ruling out MVFs.

Takigawa performed a retrospective review of 114 vertebral fracture patients (65 benign, 49 malignant), examining the MRI features of each respective entity. They similarly looked at several parameters suggestive of each disease. The authors found several statistically significant findings suggesting metastatic involvement, which included posterior wall protrusion and pedicle or posterior column involvement.

Figures A and B demonstrate orthogonal plain films demonstrating a T12 compression fracture with loss of vertebral height and minimal retropulsion into the spinal canal. Illustrations A and B demonstrate coronal and sagittal T2-weighted imaging demonstrating a horizontal linear hyperintensity, otherwise known as the fluid sign.

Incorrect Answers:
Answer 1, 3, 4, 5: these findings are characteristic of MVFs