[18F]FDG PET/CT Integration in Evaluating Immunotherapy for Lung Cancer: A Clinician's Practical Approach

The advent of immune checkpoint inhibitors (ICIs) has revolutionized the treatment paradigm of lung cancer, resulting in notable enhancements in patient survival. Nevertheless, evaluating treatment response in patients undergoing immunotherapy poses distinct challenges due to unconventional response patterns like pseudoprogressive disease (PPD), dissociated response (DR), and hyperprogressive disease (HPD). Conventional response criteria such as the RECIST 1.1 may not adequately address these complexities. To tackle this issue, novel response criteria such as the iRECIST and imRECIST have been proposed, enabling a more comprehensive assessment of treatment response by incorporating additional scans and considering the best overall response even after radiologic progressive disease evaluation. Additionally, [18F]FDG PET/CT imaging has emerged as a valuable modality for evaluating treatment response, with various metabolic response criteria such as the PERCIMT, imPERCIST, and iPERCIST developed to overcome the limitations of traditional criteria, particularly in detecting pseudoprogression. A multidisciplinary approach involving oncologists, radiologists, and nuclear medicine specialists is crucial for effectively navigating these complexities and enhancing patient outcomes in the era of immunotherapy for lung cancer. In this review, we delineate the key components of these guidelines, summarizing essential aspects for radiologists and nuclear medicine physicians. Furthermore, we provide insights into how imaging can guide the management of individual lung cancer patients in real-world multidisciplinary settings.