Pharmacological intervention with either cholecystokinin-8 (CCK-8) or
morphine during 99mTc- hepatoiminodiacetic
acid (
HIDA) cholescintigraphy 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 undesirable and should either be avoided or one should wait for at least 4 hours after
CCK-8 to begin the
99mTc-HIDA study to achieve higher specificity of the test for
acute cholecystitis. When he gallbladder is not observed by 60 mins in a clinical setting of
acute cholecystitis, a dose of 0.04 mg/kg of
morphine is administered intravenously and imaging continued for an additional 30 mins. Nonvisualization of the gallbladder by 90 mins with
morphine in an appropriate clinical setting is diagnostic for
acute cholecystitis. When the gallbladder is not observed by 60 min but is seen with
morphine administered after 60 mins, a positive diagnosis of abnormal gallbladder function can be made. When the gallbladder is observed in a clinical setting of biliary
pain or chronic 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 less than 35% is indicative of calculous or acalculous chronic
cholecystitis. The gallbladder emptying is directly related to the total number of
cholecystokinin receptors in the smooth muscle. The ejection fraction can be controlled to any desired level simply by controlling the dose rate or the duration of infusion of
CCK-8.
Morphine and other
opiate metabolites circulate for many hours in blood and act on the sphincter of Oddi and decrease the gallbladder ejection fraction. Careful
drug history, especially that of
opiates, is very critical in all subjects with a low ejection fraction before assigning an abnormality to the gallbladder motor function.