Cancer Imaging for Therapy Assessment

Monitoring tumor response following treatment is essential to tailor therapeutic strategy to achieve the most favorable clinical outcomes for cancer patients. Imaging is a non-invasive approach to assess tumor response quantitatively, and it has been clinically validated as a reliable tool. RECIST (Response Evaluation Criteria in Solid Tumors) is a published protocol to determine tumor response mainly based on change in tumor size as a response to therapy. The high-resolution anatomical information of a tumor can be obtained using computer tomography (CT), ultrasound imaging or magnetic resonance imaging (MRI). However, it is often insufficient to evaluate tumor viability and aggressiveness using only anatomical information, thus a new protocol named PERCIST (Positron Emission Tomography (PET) Response Criteria in Solid Tumors) has been recently proposed. PERCIST evaluates therapy based on the change of glycolic metabolism using

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F-FDG PET, and its effectiveness has been compared with RECIST. In addition, many other physiologic and molecular imaging modalities have been tested for more objective, rapid, and reproducible measurement of tumor response. In this chapter, both conventional and experimental non-invasive imaging modalities to evaluate therapy for cancer patients having solid tumors are reviewed.