Imaging of post-treatment changes in soft tissue sarcomas

Post-treatment imaging of soft tissue sarcomas can be challenging due to altered tissue planes and imaging characteristics due to surgery, chemotherapy and radiotherapy. Magnetic resonance imaging (MRI) provides the best diagnostic information in the post-treatment phase. It is generally supplemented by ultrasound, computed tomography (CT) for staging and PET-CT to assess the therapeutic response or tumour recurrence in challenging cases. The most common radiological dilemma is differentiating tumour recurrence from post-treatment changes. One should evaluate pre-treatment imaging thoroughly to understand imaging characteristics and then compare both pre- and post-treatment imaging to make the correct diagnosis. Recent advances in MRI, such as DWI and DCE imaging, can help increase confidence when suspected of recurrence. However, the biopsy would be the most definitive step if the dilemma persists. In this chapter, we will discuss the best practices in radiologic follow up of treated patients for timely and accurate recurrence detection.