Role of Diffusion Weighted Imaging in Differentiating Benign from Pathological Vertebral Collapse using ADC Values

Abstract

Introduction: Vertebral fractures are very commonly encountered in day to day practice. Diffusion Weighted Imaging (DWI) with Apparent Diffusion Coefficent (ADC) values is a novel technique to evaluate vertebral fractures. Aim: To establish the role of DWI in differentiating benign from pathologic vertebral fractures using ADC values in comparison with histopathology report as gold standard/laboratory evaluation and clinical follow-up. Materials and Methods: This was a prospective study of 45 adult patients. Echo Planar Imaging (EPI-DWI) with a max b-values of 600 and conventional MRI sequences were done in each of these patients. ADC values were calculated with Region Of Interest (ROI) in area of interest. Mean ADC of normal, benign and pathological vertebrae were calculated. Finally correlated with histopathological findings and clinical correlation was done. Results: Twelve cases of benign collapse either due to osteoporosis/trauma and 33 cases of pathological collapse were included in the study. Pathological collapse include 23 cases of metastasis and 10 cases of multiple myeloma. The mean ADC value in benign compression fractures was 1.466±0.325×10-3 mm2 /s and in pathological collapse was 0.959±0.288×10-3 mm2 /s. In the pathological group mean ADC in metastatic compression fractures was 0.970±0.237×10-3 mm2 /s and in multiple myeloma was 0.936±0.395×10-3 mm2 /s. The ADC was significantly higher in benign compression fractures than in pathological compression fractures (p<0.01), but the subtypes in pathological collapse between myeloma (10 cases) and metastasis (23 cases) showed considerable overlap and no statistical significance. Also, two false negative cases where ADC values were on the higher side but conventional imaging demonstrated pathological collapse. Conclusion: DWI with ADC values has considerable importance in distinguishing acute benign collapse from pathological collapse, but there is a significant overlap between metastatic collapse and multiple myeloma. Hence, we conclude that DWI with ADC maps should be a routine add-on sequence in a patient with collapsed vertebra to increase our diagnostic accuracy.

Keywords

• fracture
• metastasis
• multiple myeloma
• trauma
• vertebra