Table 2.

Classification systems for positron emission tomography evaluation of response to treatment of solid tumours, adapted from Wahl et al. [15]

Parameter	EORTC	PERCIST
Lesion measure	SUVmax and SUVmean in a manually drawn region of interest	SUV peak of the tumour lesion with greatest uptake (primary or metastatic)
Reproducibility	±25 % liver uptake	±20 % and <0.3 SUL on liver
Timing	ND	<15 min difference from injection to acquisition between scans before and after treatment
Acquisition and calibration	ND	Same scanner and reconstruction software should be used for scans before and after treatment Proper calibration required
Complete metabolic response (CMR)	No pathological FDG uptake foci	No FDG uptake foci below mean liver activity No new foci
Partial metabolic response (PMR)	After first chemotherapy cycle: SUV reduction 15–25 % After subsequent chemotherapy cycles: SUV reduction >25 %	SUL reduction >30 % in target lesion with minimum 0.8 SUL decrease No increase in SUL or size in non-target lesions
Progressive metabolic disease (PMD)	Increase >25 % tumour SUV or increase >20 % tumour longest dimension or appearance of new lesions	SUL increase >30 % in target lesion (minimum, 0.8 SUL) or visible increase of lesion extent (minimum >75 % total lesion glycolysis) or appearance of new lesions
Stable metabolic disease (SMD)	Increase <25 % or decrease <15 % tumour SUV	Not CMR, PMR, or PMD

CMR complete metabolic response, EORTC European Organization for Research and Treatment of Cancer, FDG fluorodeoxyglucose, ND not defined, PERCIST positron emission tomography response criteria in solid tumours, PMD progressive metabolic disease, PMR partial metabolic response, SMD stable metabolic disease, SUL standardised uptake value for lean body mass, SUV standardised uptake value