PET and PET-CT in Treatment Response Evaluation: Overview

Assessing tumor response to therapy is one of the most common applications of imaging in oncology. The fundamental reason for the frequent use of imaging to assess response is tumor heterogeneity. In addition to its crucial clinical role for managing treatments in individual patients, response assessment by imaging is critical for oncologic drug development. Using imaging-based end points instead of survival end points can shorten the duration of clinical trials and make new therapeutics for diseases with limited therapeutic options available significantly earlier. PET-CT is useful in treatment response evaluation. EORTC criteria and PERCIST are often used. Lugano criteria is used for the response assessment in Hodgkin and non-Hodgkin lymphomas. The new response classification response evaluation criteria in lymphoma (RECIL) is also used in response evaluation. The chapter will discuss criteria, response assessment timing, responders, nonresponders and common patterns, pitfalls, variants, advantages, and limitations.