Ratio of time-activity curves
Tissue-to-reference tissue ratio (SUV ratio) and tissue-to-blood ratio are simple analysis methods often well-suited for diagnostic semi-quantitative PET studies, but that can also be applied to quantitative studies for instance in brain receptor studies, especially for analysis of steady-state and bolus+infusion PET studies.
Ratios are dependent on the time of the measurement, and suitable ratio calculation time (and scan time) for the clinical use must be determined by first conducting a series of dynamic PET studies. In addition, studying the kinetics of the ratios can provide valuable and comprehensible information on the properties of a new radiopharmaceutical for model development.
Let us simulate some typical PET time-activity curves (TACs) to see how the ratios could be utilized:
- Late-time tissue-to-plasma ratio
- Standardized uptake value (SUV)
- Fractional uptake rate (FUR)
- Asymmetry index (AI)
- Perfusion ratio
- Bmax and KD
- Retention index (RI)
- Static late scan
- Fitting TTACs
Carson RE. PET physiological measurements using constant infusion. Nucl Med Biol. 2000; 27(7): 657-660. doi: 10.1016/S0969-8051(00)00138-4.
Updated at: 2019-04-02
Created at: 2019-03-31
Written by: Vesa Oikonen