Portal shunt scintigraphy (PSS) in the evaluation of patients suspected of hereditary hemorrhagic telangiectasia

Objectives Hereditary hemorrhagic telangiectasia (HHT) is a rare disease characterized by angiodysplastic lesions of telangiectases and vascular malformations (VMs) that affect various organs including the liver. Clinical manifestations are correlated to three predominant hepatic shunt patterns: arterio-venous, arterio-portal, portal-venous. Several small studies have shown improvement in HHT patients with predominant high output cardiac failure after embolization of hepatic VMs. However, hepatic or biliary necrosis may occur if inadequate portal blood flow supplies the liver. Therefore, porto-venous shunts should be evaluated prior to embolization. We applied PSS to measure the portal shunt index (PSI) as described by Shiomi.

Methods Six patients were referred for evaluation of possible HHT. The final diagnosis HHT (4), cirrhosis (1), nodular regenerative hyperplasia (NRH) (1) was based on clinical evaluation and various combinations of diagnostic examinations: CT, angiography, ultrasound and PSS. An 18Fr polyethylene urinary catheter tube was placed into the upper rectum. 99mTc-PO4 370 MBq in 2ml saline, followed by 15 ml of room air, was given through the tube. Anterior dynamic images of the liver and the heart were obtained for a total of 5 minutes. Regions of interest were drawn over the liver and cardiac blood pool to generate a time activity curve to calculate a PSI.

Results All 6 patients had abnormal PSI values (normal < 5.9%) with values ranging from 10.8-88%. The patient with the highest PSI (88%) also had the most severe symptoms and features of HHT. The lowest PSI (10.8%) was found in a patient with HHT but CT showed no VMs. The patient with NRH had an initial PSI of 29% but became normal (4%) after therapy.

Conclusions The PSI may be a useful non-invasive technique for evaluating patients suspected of HHT and identifing patient who may be at risk from embolization therapy where the loss of hepatic arterial blood flow will lead to hepatic and biliary necrosis.

Research Support Wagner-Torizuka Fellowship Progra