TRANSSPLENIC PORTAL SCINTIGRAPHY USING ⁹⁹MTC-MEBROFENIN IN NORMAL DOGS

Transsplenic portal scintigraphy using sodium pertechnetate is superior to per-rectal portal scintigraphy due to improved visualization of the portal vasculature with decreased patient and personnel exposure. The purpose of this study was to describe the use of ⁹⁹mTc-mebrofenin, the radiopharmaceutical of choice for the evaluation of hepatic function, in place of pertechnetate for transsplenic portal scintigraphy in normal dogs. Sixteen juvenile dogs underwent transsplenic portal scintigraphy using 37-130 MBq ⁹⁹mTc-mebrofenin in a 0.2-0.5 ml volume. After the initial dynamic acquisition obtained at 4 frames/s in right lateral recumbency, static right lateral, and ventral views were obtained at 5, 10, 15, 20, 25, 30, 40, 50, and 60 min. A nuclear angiogram of the splenic and portal veins was visible in all dogs, followed by rapid distribution of the radiopharmaceutical in the liver. Hepatic morphology was more easily defined than with pertechnetate. Transit time could not be calculated due to the high hepatic extraction of ⁹⁹mTc-mebrofenin. Mean±SD shunt fraction was 0.8±0.8%. Time to peak liver activity was 3.1±1.1 min, and hepatic excretion T₁/₂ was 19.4±6.3 min. No visible blood pool and cardiac activity was seen after 5 min. The mean±SD time to visualization of defined biliary activity was 8.8±2.9 min. Absorption from the spleen was significantly higher than that reported for pertechnetate (87.9±8.2%, vs. 52.5±19.1%). ⁹⁹mTc-mebrofenin can be used in place of pertechnetate for transsplenic portal scintigraphy, with the advantage of combining quantitative parameters of liver function with the already known advantage of transsplenic portal scintigraphy.