Role of Diffusion Weighted MRI in Characterization of Musculoskeletal Soft Tissue Tumors

Abstract Background: Magnetic Resonance Imaging is the method of choice for the diagnostic work-up of soft tissue tumors. It is the modality of choice to evaluate such masses, because of its excellent soft tissue contrast. Aim of Study: To assess the efficacy of Diffusion weighted MRI in characterization of musculoskeletal soft tissue tumors. Patients and Methods: The current study enrolled 20 patients (11 female and 9 male) with musculoskeletal STTs with mean age was 41.08±11.54 year. The most frequent affected site with the swelling was the thigh (48%) followed by the arm (20%). Four (16%) patients suffered from leg swelling while three (12%) patients had shoulder swelling. Our results revealed that malignant musculoskeletal soft tissue masses had significantly lower ADC value in comparison to those with benign masses (0.70±0.09 vs. 1.58±0.52x10-3m2/s; p < 0.001). Results: Patients with malignant lesions had significantly lower ADC value in comparison to those with benign lesions (0.70±0.09 vs. 1.58±0.52 (103mm2/s). Myxoma had the highest ADC value that was 2.44 (103mm2/s) while sarcoma had lowest value that was 0.54±0.03 (103mm2/s). It was noticed that MRI had 100% sensitivity and 81.8% specificity for diagnosis of malignant musculoskeletal soft tissue masses with overall accuracy was 92% and area under curve was 0.91 at cut off value was <1.14 (103mm2/s). Based on final diag-nosis; MRI was successful in diagnosis of all cases with malignant musculoskeletal soft tissue masses but as the same time, MRI falsely diagnosed two cases with benign nature to be malignant. Those two cases were finally diagnosed to be lipoma. Conclusion: Based on the current study, DWI-MRI con-sidered the method of choice for the characterization of muscul oskel etal STTs; however, DW-MRI with ADC mapping is a rapidly, valuable, non-invasive, non-contrast tool for reliably differentiating between benign and malignant STTs. It's recommended to perform such study in large sample of patients and in more centers to confirm the great values of DWI-MRI in evaluation of such lesions.