Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST)

Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST) makes use of positron emission tomography (PET) to provide functional information to help determine tumour viability.

The criteria consist of four categories: complete metabolic response (CMR), partial metabolic response (PMR), progressive metabolic disease (PMD), and stable metabolic disease (SMD). 

As used below, SUL is the standardised uptake value corrected for lean body mass. SULpeak (or SUL_peak) is the peak SUL in a spherical 1 cm³ volume of interest (VOI).

Complete metabolic response (CMR)

• complete resolution of 18F-FDG uptake within the measurable target lesion

  • so that it is less than mean liver activity
  • so that it is at the level of surrounding background blood pool activity
• disappearance of all other lesions to background blood pool levels
• no new suspicious 18F-FDG avid lesions
• if progression according to RECIST criteria, must verify with follow up

Partial metabolic response (PMR)

• reduction of a minimum of 30% in target measurable tumour 18F-FDG SUL peak, with absolute drop in SUL of at least 0.8 SUL units.
• no increase >30% of SUL or size in all other lesions
• no new lesions

Stable metabolic disease (SMD)

• no CMR, PMR, or progressive metabolic disease (PMD)
• no new lesions

Progressive metabolic disease (PMD)

• >30% increase in 18F-FDG SUL peak, with >0.8 SUL units increase in tumour SUL from the baseline scan in pattern typical of tumour and not of infection/treatment effect
• or visible increase in the extent of 18F-FDG tumour uptake.
• or new 18F-FDG avid lesions typical of cancer and not related to treatment effect and/or infection.