Kinetic modelling of hepatic function in rats using a dedicated small-animal SPECT: Initial experience

1311 Objectives To present the first results on kinetic modelling of dynamic liver SPECT (DLS) acquired on a dedicated small animal SPECT system. Methods We performed DLS under peritoneal anaesthesia in 5 healthy Sprague Dawley rats on the YAP-(S)PET system. Following the intravenous injection of a mean activity of 91±33MBq of Tc-99m-mebrofenine, a list mode acquisition of 32 frames (4*30sec, 28*1min) was started. Arterial blood samples were collected to measure the input function. A one-tissue compartment model was applied to fit hepatic tissue time activity curves derived from spherical VOI9s drawn on the liver tissue. Global k1 and k2 values, representing kinetics of liver uptake and thus hepatocellular function, were estimated using the PMOD software. Additionally, we calculated parametric images for k1 and k2. Results The global mean±SD k1 and k2 values were 0.48±0.16 and 0.14±0.03 ml/ccm/min, respectively. The individual values for all rats are summarized below. The obtained values were independent of the amount of injected tracer. However, image quality improved substantially with the amount of radioactivity. Conclusions Pixelwise kinetic modelling of DLS proved to be feasible in this study. The influence of anaesthesia, attenuation and partial volume effect corrections as well as a tissue compartment model for bile excretion remain to be studied in further experiments.