Organ perfusion by dynamic scintigraphy convection-diffusion tracer kinetics in a phantom
Dynamic scintigraphy is used widely to evaluate qualitatively the perfusion of an organ. Attempts to quantify blood flow to an organ by means of scintigraphic imaging modalities have often employed assumptions that lead to oversimplifying the physiology of the tracer kinetics. We used a mathematical formalism described by W. Perl and F. P. Chinard (Circ. Res. 22: 273-298, 1968), the convection-diffusion tracer kinetics, model, for parameter evaluation of flow (F) and volume of distribution (V). This modeling methodology was evaluated using a circulatory phantom with absolute flow measured independently by flowmeter. In a series of 22 phantom experiments with F/V < 0.32 s-1, there was a strong correlation between F and flow probe measurement [r = 0.97; slope = 1.08 +/- 0.06 (SE)]. The theoretical analysis comparing this approach with classical tracer kinetics methods explains both the satisfactory results for F/V using mean transit time and the systematic overestimation of F/V using decay constant methods.