Immune-Modified 18F-FDG PET Response Criteria—LYRIC and iPERCIST
| Parameter | LYRIC (19,20) | iPERCIST (22) |
| Tumor type | HL | NSCLC |
| ICI | Anti-PD-1 | Anti-PD-1 |
| n | 16 | 28 |
| Timing | 3 mo | 2 mo |
| Standard of reference | Multidisciplinary experts’ consensus based on clinical and imaging results | Clinical benefit and confirmatory 18F-FDG PET/CT or CT 4 wk later |
| Definition of response | CR or PR: per Lugano (21) | CMR, PMR, or SMD: per PERCIST |
| Definition of progression | Per Lugano with following exceptions | PMD as per PERCIST is considered UPMD |
| IR1: ≥50% increase in SPD in first 12 wk | ||
| IR2a: <50% increase in SPD with new lesions | UPMD needs to be confirmed by second 18F-FDG PET/CT at 4–8 wk later to be classified as CPMD | |
| IR2b: <50% increase in SPD with ≥50% increase in PPD of lesion or set of lesions at any time during treatment | ||
| IR3: increase in 18F-FDG uptake without concomitant increase in lesion size meeting criteria for PD | ||
| Emphasis and advantages | Introduction of concept of IR categories until biopsy or subsequent imaging confirms either pseudoprogression or true progression | Introduction of concept of UPMD with clinical stability |
| Allowing treatment continuation |
PECRIT = PET/CT Criteria for Early Prediction of Response to ICI Therapy; PERCIMT = PET Response Evaluation Criteria for Immunotherapy; imPERCIST = Immunotherapy-Modified PERCIST; LYRIC = Lymphoma Response to Immunotherapy Criteria; iPERCIST = Immune PERCIST; HL = Hodgkin lymphoma; PR = partial response; CR = complete response; SD = stable disease; LDH = lactate dehydrogenase; PE = physical examination; CMR = complete metabolic response; PMR = partial metabolic response; SMD = stable metabolic disease; PD = progressive disease; SULpeak = lean body mass–corrected SUVpeak; PMD = progressive metabolic disease; UPMD = unconfirmed PMD; IR = indeterminate response; SPD = sum of product of diameters; CPMD = confirmed progressive metabolic disease; PPD = product of perpendicular diameters.