Acute benign vertebral compression fractures: "see-through sign" on contrast-enhanced MR images

To retrospectively evaluate the diagnostic role of the contrast-enhanced MRI (CE-MRI) for differentiation between benign VCFs and malignant VCFs focusing on the internal transparent trabecular bone on CE-MRI (the "see-through sign").

The institutional review board approved this study and informed consent was waived due to the retrospective nature of the study. From January 2012 to December 2013, all 149 consecutive benign or malignant VCF patients were enrolled for consideration in this study from a CE-MRI database. In the first analysis, four radiologists independently evaluated the presence or absence of the see-through sign. The see-through sign was defined as internal transparent trabecular bone morphology on CE-MRI. The intraclass correlation coefficient (ICC), percentage agreement, and Fleiss's kappa statistics were obtained.

Fifty-seven patients (M:F = 27:30; mean age, 63 years; age range, 20-88 years) who diagnosed as acute benign (n = 24) and malignant (n = 33) VCFs were finally included for the analysis. The results of all readers showed that the see-through sign was associated with acute benign VCFs (p < 0.05). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) of the see-through sign ranged from 75-96, 70-88, 66-85, 81-97 %, respectively. The inter-observer reliability of the see-through sign was sufficient with ICC = 0.847, percentage agreement = 78.9, and κ = 0.578.

The see-through sign on CE-MRI is featured in acute benign VCFs, and it can be a useful finding to differentiate between benign and malignant VCFs.