Observation of portal circulation through superior mesenteric vein by enteric coated capsule of thallium-201

Evaluation of portal circulation through the superior mesenteric vein with an enteric capsule of [123I]iodoamphetamine

We report a method by which the contribution of the superior mesenteric vein to the portal blood flow can be evaluated noninvasively. An enteric-coated capsule containing [123I]iodoamphetamine is given by mouth 3h before the examination. The data obtained are treated by computer to calculate the portal shunt index (SI) through the superior mesenteric vein. The SI was higher for more severe liver disorders, Increasing in the order of chronic persistent hepatitis, chronic aggressive hepatitis, and cirrhosis. The SI was higher in cirrhotic patients than in chronic hepatitis patients or healthy volunteers (both, P < 0.0001). The SI was higher in cirrhotic patients with esophageal varices than in such patients without varices (P < 0.05). The SI was higher in cirrhotic patients with ascites than in such patients without ascites (P < 0.001). The SI was higher in cirrhotic patients with encephalopathy than in those without encephalopathy (P < 0.01). Correlation was significant between the SI and classical indicators of functional reserve. This method is clinically useful.

Contribution of scintigraphy to verify the reliability of different preparation processes for enteric coated capsules

The aim of this work was to use radiopharmaceuticals such as technetium (99mTc) and indium (DTPA-Ca111In) to visualize, with a gamma-camera, the disintegration area and time of 3 types of enteric coated hard gelatin capsules (obtained by 3 different preparation processes) and thus, to verify that they are really resistant in gastric fluids and soluble in intestinal zones. Results are well correlated with those previously obtained in vitro (disintegration, dissolution) and in vivo (profiles of plasmatic concentrations versus time).

Assessment of portosystemic shunting from superior mesenteric vein by duodenal administration of iodoamphetamine I123

Portosystemic shunting (PSS) from the superior mesenteric vein (SMV) was evaluated with the duodenal administration of iodoamphetamine I123 (IMP) in patients with chronic hepatitis and liver cirrhosis. After duodenal intubation, IMP was administered through a tube, and then scintigraphy including the pulmonary and hepatic regions was performed. In all patients, images of the liver and/or lungs were observed within 10 min and became clear with time, due to a good absorption of IMP from the intestine. On the other hand, IMP appears not to be absorbed from the stomach. The portosystemic shunt index was calculated by dividing counts of lungs by counts of liver and lungs. The shunt index (mean +/- SE) was 1.5% +/- 0.8%, 12.6% +/- 3.7% and 28.3% +/- 4.5% in chronic hepatitis, compensated cirrhosis and decompensated cirrhosis, respectively. This index was significantly higher in cirrhosis, especially in decompensated cirrhosis. Therefore, transintestinal portal scintigraphy with IMP could be a useful method for the non-invasive and quantitative evaluation of PSS from the SMV in portal hypertension.

Significance of blood flow in the inferior and superior mesenteric veins for the formation of oesophageal varices

The degree of involvement of blood flow in the superior mesenteric vein and inferior mesenteric vein in the formation of oesophageal varices is not known. We have developed a method by which the contributions of these veins to portal blood flow can be evaluated simultaneously in a relatively non-invasive way. An enteric-coated capsule containing [123I]iodoamphetamine (IMP) is given by mouth and 3 h later [123I]IMP is instilled into the rectum. The data obtained are treated by computer to calculate the portal shunt index via the inferior and superior mesenteric veins. In chronic hepatitis and cirrhosis, when varices were absent, the difference in these indices was not significant. In the presence of varices, the portal shunt index via the inferior mesenteric vein was significantly higher than that via the superior mesenteric vein. It was suggested that the contribution of blood flow in the inferior mesenteric vein the portal/splenic axis is important in the formation of varices.

Portal circulation in monkeys and humans studied after ingestion of a capsule containing a radionuclide

Capsules (8 x 30 mm) of technetium-99m pertechnetate were designed for measurement of portal blood flow. Most of the radionuclide entered the superior mesenteric vein. The capsule was taken orally and monitored with a collimator for scintigraphy until it reached the small intestine, when a magnetic field completed an electrical circuit in a sensor, burning a thread, releasing a spring, and discharging the preparation. A study in crab-eating monkeys (Macaca fascicularis) showed that the radionuclide in the small intestine circulated through the superior mesenteric vein to the portal vein and liver. Portal scintigraphy through the small intestine could be analysed in the same way as per-rectal portal scintigraphy, in which blood flow mostly from the inferior mesenteric vein is evaluated. A study of four volunteers showed that, after the radionuclide was released, it circulated through the superior mesenteric vein to the portal vein and liver. Use of a capsule enclosing a radioisotope was possible, and the procedure seemed to be safe. The use of the per-small intestine method plus the per-rectal method should give more accurate results than either method used alone, because the haemodynamics of both the superior and inferior mesenteric vein would be reflected.