Should SPECT/CT imaging be standard protocol when gallbladder uptake is not seen on hepatobiliary scintigraphy evaluating for either acute or chronic cholecystitis?

1328 Objectives To determine the need to incorporate SPECT/CT imaging as standard protocol when gallbladder uptake is not seen on hepatobiliary scintigraphy evaluating for either acute or chronic cholecystitis. Methods 36 year old female with intermittent right upper quadrant abdomen pain for the past several months with nausea and diarrhea was consented for a hepatobiliary study to evaluate for biliary dyskinesis. The patient was injected with 5.32 mCi of Tc99m - mebrofenin. Dual headed gamma camera was used for the initial two hours of dynamic imaging, anterior images at approximately one hour, two hours and right lateral and anterior images at around 4 hours after radiotracer injection. SPECT with 16 slices CT hybrid system was used for imaging at 4 hours and 30 minutes after radiotracer injection. Results Planar HIDA scan demonstrated no gallbladder filling at one, two and four hours of imaging. There was no appreciable increased radiotracer uptake within the gallbladder fossa. There was visualization of the common bile duct and bowel activity within 20 minutes. Usually, the diagnosis of acute cholecystitis is given if there is no radiotracer seen in the gallbladder by 4 hours after radiotracer injection. However, symptomatically, the diagnosis of acute cholecystitis was not appropriate for the patient. The patient was not in acute distress at the time of the exam. Additional SPECT/CT imaging was acquired which demonstrated minimal radiotracer uptake in the gallbladder. Conclusions Hepatobiliary scintigraphy, known as HIDA scan, is often used to evaluate for cystic duct patency or occlusion in patient when there is suspicion of acute cholecystitis. A HIDA scan can also assess for biliary dyskinesis or chronic cholecystitis with the aid of sincalide (CCK) administration. There are times when further anatomical information is warranted to determine whether or not there is gallbladder filling of radiotracer. Single-photon emission computed tomography with computed tomography (SPECT/CT) provides an advantage over planar HIDA scan because of the additional anatomical correlation. This educational exhibit demonstrates the advantage of using SPECT/CT imaging in conjunction with a HIDA scan. Many clinicians use SPECT/CT imaging’s unique feature of combining function and anatomy to separate bowel activity from gallbladder activity in evaluating for acute or chronic cholecystitis or distribution of radiotracer activity in bile leak studies. However, SPECT/CT imaging may also be indicated to show radiotracer uptake in the gallbladder when no appreciable increased radiotracer uptake activity is seen in the gallbladder fossa on the planar images. Thus, we believe that SPECT/CT imaging should be the standard protocol when gallbladder uptake is not seen on hepatobiliary scintigraphy evaluating for either acute or chronic cholecystitis. Similar presentation with chronic cholecystitis that had non-visualization of the gallbladder at 4 hours on planar HIDA scans has been reported in literature. This finding raises a few interesting questions. Is there truly no radiotracer uptake in the gallbladder on planar HIDA scans for some patients suspected of chronic cholecystitis? Can SPECT/CT demonstrate actual gallbladder filling for symptomatic patients diagnosed with acute cholecystitis based on non-filling gallbladder planar images? The ultimate management may not change, but the timeline to take a patient to surgery may change. Further studies are needed to determine how visualization of gallbladder on SPECT/CT versus planar imaging can affect patient outcome. RESEARCH SUPPORT: None