Fig. 3

Positron emission tomography (PET) maximum intensity projection (MIP) images and axial images from the chest, abdomen, and pelvis demonstrating the radiographic response to pembrolizumab therapy. a Baseline imaging shows extensive metastatic disease burden, and green arrows highlight lesions first to improve in lung, mediastinum, and axillary lymph nodes. b Imaging after 3 months (4 cycles) of pembrolizumab are consistent with mixed response and pseudoprogression, with several new hypermetabolic foci (red arrows) in soft tissue, liver and bone. c Imaging studies at 6 months shows a near complete response to 7 cycles of pembrolizumab, with regression of multiple hypermetabolic metastatic foci, and few small remaining foci of residual hypermetabolism in the chest and abdomen. d Imaging at 12 months shows persistent FDG avidity in mediastinal and abdominal lymph nodes and new FDG avid lesions in liver and small bowel (red arrows)