Measurement of portal systemic circulation by oral and per-rectal administration of I-123 iodoamphetamine

In an earlier study, we measured the portal circulation noninvasively by Tc-99m pertechnetate per-rectal portal scintigraphy. This method makes it possible to see the portal circulation and to diagnose portal hypertension from the images of the liver and heart. However, the method mainly reflects circulation from the inferior mesenteric vein, the contribution of which to the portal circulation is less than that of the superior mesenteric vein. Here, we devised capsules of I-123 iodoamphetamine (IMP) that dissolve when the pH changes to evaluate the portal circulation arising from the superior mesenteric vein. I-123 IMP enclosed in an enteric-coated capsule was prepared and given orally, just before I-123 IMP was injected into the rectum. The per-rectal portal shunt index (RSI) and oral portal shunt index (OSI) were calculated from the count of radioactivity of the liver and lungs. The RSI and OSI of patients with cirrhosis were both higher than those of the patients with chronic hepatitis. In individual patients, the RSI was higher than the OSI. This noninvasive method seemed to be useful in evaluation of the portal systemic circulation in chronic liver diseases.