Tc-99m HIDA dosimetry in patients with various hepatic disorders.

The pharmacodynamics of Tc-99m dimethyliminodiacetic acid were studied for normal subjects and for patients with a variety of hepatobiliary disorders. It was determined that, in normal subjects, approximately 65% of the gallbladder agent bypassed the gallbladder and was excreted directly from the liver into the small intestine. This bypassing of the gallbladder was even higher in patients with cystic-duct or common-duct obstruction. The radiation burdens to the gallbladder wall and other critical organs were calculated using the dynamic data obtained from patients with a variety of gallbladder disease. The dose to the gallbladder wall was found to be significantly lower than previously reported. Gallbladder ejection and clearance characteristics when stimulated by food intake were studied for normal subjects. Dosimetry calculations demonstrated a fivefold reduction of absorbed dose to the gallbladder wall when the gallbladder was stimulated to contract using a fatty meal. Accordingly, a fatty meal is recommended for patients at the end of all gallbladder imaging studies.