Fitting the blood-to-plasma or plasma-to-blood ratios
The plasma must be separated from blood, and the radioactivity and mass of both plasma and blood samples (or the precipitant left in the tube after most of plasma is removed) must be measured. Radioactivity measurement is hampered by the fast decay of radioactivity, especially with C-11 labeled radiopharmaceuticals. Fitting of a mathematical function to the fraction curves reduces variation and enables interpolation and extrapolation of the ratio curve, for the conversion of blood TAC to plasma.
The plasma-to-blood and blood-to-plasma ratio curves can be very different for different radiotracers, and therefore a suitable function must first be selected.
, where p1 < 0. Similar function was used to fit blood-to-plasma ratio curves by Tarkia et al (2012):
Function parameters are saved into specific fit file format, which are ASCII text files.
- Blood to plasma conversion
- Plotting curves
- Blood sampling
- Processing input data
- Fitting PET input curves
Lee J-S, Su K-H, Lin J-C, Chuang Y-T, Chueh H-S, Liu R-S, Wang S-J, Chen J-C. A novel blood-cell-two-compartment model for transferring a whole blood time activity curve to plasma in rodents. Comput Methods Programs Biomed. 2008; 92(3): 299-304. doi: 10.1016/j.cmpb.2008.02.006.
Updated at: 2018-12-18
Created at: 2016-04-06
Written by: Vesa Oikonen