Summary of PET-Based and CT-Based Response Assessment Criteria for Immunotherapy Response Evaluation
| 18F-FDG PET/CT– based criteria | CT-based criteria | ||||
|---|---|---|---|---|---|
| Response | PERCIST | imPERCIST | Response | RECIST | iRECIST |
| PMD | >30% relative increase and >0.8 absolute increase in SULpeak of hottest lesion or unequivocal progression of 18F-FDG–avid nontarget lesion or appearance of new 18F-FDG–avid lesion | Defined only by increase in sum of SULpeak of 5 lesions by 30% | PD | ≥20% increase in sum of diameters of TLs or unequivocal progression of NL or appearance of new lesion | iUPD: ≥20% of sum of longest diameters compared with nadir (minimum, 5 mm) or progression of nontarget lesions or new lesion; confirmation of progression recommended at minimum of 4 wk after first iUPD assessment |
| iCPD: increased size of target or nontarget lesions; increase in sum of new target lesions > 5 mm; progression of new nontarget lesions; appearance of another new lesion | |||||
| SMD | Not meeting criteria for CMR, PMR, or PMD | Not meeting definitions for CMR, PMR, or PMD | StD | Neither sufficient TR nor sufficient TG to qualify for PR or PD | Neither sufficient TR nor sufficient TG to qualify for PR or PD |
| PMR | >30% relative decrease and >0.8 absolute decrease in SULpeak of hottest lesion | Decrease in sum of SULpeak by at least 30% | PR | ≥30% decrease in SoDs of TLs; NLs may persist but not unequivocally progress | ≥30% decrease in SoDs of TLs; NLs may persist but not unequivocally progress |
| CMR | Complete resolution of 18F-FDG uptake within measurable target lesion and disappearance of all other lesions to background blood-pool levels | Resolution of all malignant lesions; nominally assigned SULpeak of zero for quantitative analysis | CR | Disappearance of all TLs and NLs; all LNs < 10 mm on short axis | Disappearance of all TLs and NLs; all LNs < 10 mm on short axis |
LN = lymph node; NL = nontarget lesion; TG = tumor growth; TL = target lesion; TR = tumor regression; iUPD = unconfirmed PD; iCPD = confirmed PD; SoD = sum of diameters.