CHOLECYSTOKININ AND MORPHINE PHARMACOLOGICAL INTERVENTION DURING TC-99M-HIDA CHOLESCINTIGRAPHY - A RATIONAL APPROACH

Pharmacological intervention with either cholecystokinin-8 (CCK-8) or morphine during Tc-99m- hepatoiminodiacetic acid (HIDA) cholescintigra phy is required primarily for the assessment of the diseases affecting the gallbladder, the common bile duct, or the sphincter of Oddi. For imaging, the patient should be prepared by an overnight fast, or with 4 hours of minimum fast. Pre-emptying with CCK-8 is probably undesirab le and should either be avoided or one should wait for at least 4 hour s after CCK-8 to begin the Tc-99m-HIDA study to achieve higher specifi city of the test for acute cholecystitis. When the gallbladder is not observed by 60 mins in a clinical setting of acute cholecystitis, a do se of 0.04 mg/kg of morphine is administered intravenously and imaging continued for an additional 30 mins. Nonvisualization of the gallblad der by 90 mins with morphine in an appropriate clinical setting is dia gnostic for acute cholecystitis. When the gallbladder is not observed by 60 min but is seen with morphine administered after 60 mins, a posi tive diagnosis of abnormal gallbladder function can be made. When the gallbladder is observed in a clinical setting of biliary pain or chron ic calculous or acalculous cholecystitis, CCK-8 at a dose rate of 3.3 ng/kg/min is infused intravenously for 3 mins (10 ng/kg/3 min) for the measurement of the ejection fraction. An ejection fraction value of l ess than 35% is indicative of calculous or acalculous chronic cholecys titis. The gallbladder emptying is directly related to the total numbe r of cholecystokinin receptors in the smooth muscle. The ejection frac tion can be controlled to any desired level simply by controlling the dose rate or the duration of infusion of CCK-8. Morphine and other opi ate metabolites circulate for many hours in blood and act on the sphin cter of Oddi and decrease the gallbladder ejection fraction. Careful d rug history, especially that of opiates, is very critical in all subje cts with a low ejection fraction before assigning an abnormality to th e gallbladder motor function. (C) 1996 by W.B. Saunders Company