The Role of Diffusion-Weighted MRI in the Evaluation of Musculoskeletal Tumors in the Pediatric Age Group

Abstract

Clinically, musculoskeletal lesions in children present a wide spectrum of diseases, but most of them are benign. Malignant tumors of bone and soft tissue are less common, but present an important differential diagnosis. Our aim is to guide invasive diagnostic measures and limit the proportion of patients with benign disease who undergo biopsy and aid in the follow up of tumors. Diffusion-weighted imaging (DWI) yields qualitative and quantitative information that reflects tissue cellularity and cell membrane integrity, which complements the morphologic information obtained by conventional MR imaging. Qualitative analysis is achieved via visual assessment of the relative tissue signal attenuation of both the DW image and the ADC parametric map. Quantitative analysis is performed by calculating the conventional ADC value and/or perfusion-insensitive diffusion coefficient (PIDC) value. The PIDC map provides more accurate information about tumor tissue cellularity by minimizing vascular contributions, which are higher in malignant tumors. DWI could provide earlier identification of patients with a poor treatment response or of those with tumor recurrence. This is because cellular death and vascular changes in response to treatment precede changes in lesion size.Therefore, DWI could provide an opportunity to adjust individual treatment regimens more rapidly, sparing patients the unnecessary morbidity, expense, and delays in the initiation of effective treatment . WB-MRI and DW techniques has been proven to be an extremely useful method for multifocal diseases and oncology with the same routine MR contraindications. It should be, respecting the limitations inherent to any radiology method, accepted as another powerful tool, especially in pediatric oncology, avoiding radiation exposure related disease and being more available to these patients.