Morphine-Modified Hepatobiliary Scanning Protocol for the Diagnosis of Acute Cholecystitis

We report a morphine-modified hepatoiminodiacetic acid (HIDA) scanning protocol that uses 2 mg of morphine IV push at the bedside as a pretreatment. We compared this protocol with the original HIDA scanning protocol, which included delayed imaging for up to 4 hours without the use of morphine. Moreover, we contrast our results with the results of studies in the literature.

We retrospectively reviewed the charts of inpatients who underwent HIDA scanning for the diagnosis of acute cholecystitis between 2003 and 2013. The study group consisted of 374 HIDA studies of 365 patients who received 2 mg of morphine IV push at bedside and then underwent dynamic imaging for 1 hour using 222 MBq of ^99mTc-mebrofenin. No delayed images were obtained. The control group consisted of 232 studies of 227 patients who underwent conventional HIDA scanning using our standard protocol with delayed imaging and without morphine. Either strict pathologic criteria or the results of a percutaneous gallbladder drainage procedure were used for the confirmation of acute cholecystitis.

The true-negative rate in the study group was 77% and in the control group, 72%. The positive predictive value in the study group was 81% and in the control group, 45%. The negative predictive value in the study group was 98% and in the control group, 99%. The accuracy in the study group was 95% and in the control group, 84%. The sensitivity in the study group was 93% and in the control group, 93%. The specificity in the study group was 95% and in the control group, 83%. The differences in the true-negative rate, accuracy, specificity, and positive predictive value of the morphine-modified protocol used for the study group and the original protocol used for the control group were statistically significant (p < 0.0005).

Pretreatment using 2 mg of IV morphine at bedside before radionuclide imaging is superior to routine HIDA scanning with only delayed images for the diagnosis of acute cholecystitis. The results of our pretreatment morphine-modified protocol are comparable to those reported in the literature for posttreatment morphine-augmented protocols.