The Role of Diffusion-Weighted MRI in the Characterization of Musculoskeletal Soft Tissue Tumors

Abstract

usculoskeletal soft-tissue tumors are arising from ectodermal and mesodermal layers (David et al., 2011). They can generally be classified into two main categories, that is, soft-tissue sarcomas and benign tumors, and these tumors can occur at any age and present at any site (Pencavel et al., 2010). MRI is indispensable in the evaluation of soft tissue tumors and become modality of choice. It offers improved soft tissue contrast when compared to other modalities (Goldblum et al., 2013). There are some finding on MRI which are indicative for malignancy, such as infiltration of adjacent tissue destruction of bones and tendons and the size of mass, there are no criteria available to clearly distinguish benign mass from malignant, some very aggressive tumors present as encapsulated mass without surrounding edema and only minimal enhancement which are in general indicative for benign process. Thus, histopathologic work up is required for reliable characterization of soft tissue tumors (Andreas et al., 2007). The DWI now used in association with conventional MRI with the objective of improving diagnostic accuracy and treatment evaluation. DWI allow quantitative and qualitative analysis of tissue cellularity and cell membrane integrity and has been widely used for tumor detection and characterization to monitor treatment response (Koh and Collins, 2007). The tissue contrast using diffusion weighted image (DWI) is different from that attained using conventional MR technique. The DWI involves the diffusion motion of water protons in tissue, which produces different contrast in different kinds of tissue, because of this procedure provide different information about diseased tissue (Nagata et al., 2008). DWI has the potential to differentiate benign from malignant soft tissue tumors because malignant tumors have greater cellularity with more restricted diffusion than benign tumors (Maeda et al., 2007).