Experimental study of per-rectal portal scintigraphy using 99mTc-HM-PAO

Usefulness of per-rectal portal scintigraphy by 123I-IMP has already been admitted. We assessed whether 99mTc-HM-PAO, another agent used for cerebral blood flow scintigraphy, could be utilized for scintigraphic evaluation of the portal system. Animal experiments were carried out to evaluate the usefulness of the examination. Shunt indices obtained from per-rectal portal scintigraphy by 123I-IMP and 99mTc-HM-PAO in shunt models and shunt rate obtained by direct injection of 99mTc-MAA into the inferior mesenteric vein under laparotomy were compared. Correlation coefficient of each agent with 99mTc-MAA was 0.90 for 99mTc-HM-PAO and 0.80 for 123I-IMP. It was also noted that as larger quantity of the tracer could be administered in 99mTc-HM-PAO than in 123I-IMP, absorption from rectum was optimum and liver extraction fraction was 94.4%. Therefore, we concluded that 99mTc-HM-PAO was useful for per-rectal portal scintigraphy. (author)