MRI for Diagnosing Musculoskeletal Tumors: A Qualitative and Quantitative Analysis of Tissue Composition

Musculoskeletal (MSK) tumors are neoplasms that arise in the bones, cartilage, muscles, tendons, nerves, and synovium. These lesions are highly diverse, comprising various tissue components such as mature fat, fluid, hematoma, and fibrous tissue. MRI is a crucial modality for diagnosing MSK tumors, providing both qualitative and quantitative assessments of tissue composition. The key tissue components of MSK tumors that are identifiable on MRI include mature fat and fluid. However, hyperintense mimickers-such as subacute hematomas on T1-weighted image (T1WI) and pseudocystic lesions on T2-weighted image (T2WI)-can complicate MRI interpretation. Masses with non-specific MRI features-such as intermediate signal intensity (SI) on T1WI and high SI on T2WI-require differential diagnosis. Special attention should be paid to the tumor's specific location, imaging signs, patterns of low-SI foci on both sequences, and features suggestive of malignancy, with biopsy indicated in uncertain cases. Advanced MRI techniques enhance diagnostic precision. DIXON quantifies fat content, diffusion-weighted imaging assesses cellularity with tumor heterogeneity, and dynamic contrast-enhanced MRI quantifies perfusion. Ultimately, integrating conventional and functional MRI analyses is essential to accurately characterize the diverse and complex nature of MSK tumors.