There are multiple definitions:

1. target-to-background ratio(English)

   • correction procedure for background activity. Calculated by dividing the SUVmax of the arteries by the SUVmean of the caval veins (blood pool)
   • RAGE, SUV, AIx, BMI, CRP, PWV, SBP, FDG, PET
   • Medical imaging, Ratio-based metric, Nuclear medicine
   • https://doi.org…heartj/ehaa1095
   • https://doi.org…0/ijms231810268
   • https://doi.org….2337/dc16-0327

2. tumor-to-background ratio(English)

   • ROI, SUV, PET, OSEM
   • Medical imaging, Ratio-based metric
   • https://pubmed.…h.gov/15347719/

3. time below rang(English)

   • BMI, MAGE, NAH, CGM, LAGE
   • Endocrinology
   • https://doi.org…ndo.2022.858912