FDG-PET/CT in the Evaluation of Patients With Suspected Cholecystitis

This is a pilot study to investigate the ability of fluorodeoxyglucose-positron emission tomography (FDG-PET) and Positron emission tomography-computed tomography (PET/CT) as a direct method of detecting infection and/or inflammation of the gallbladder.

Hepatobiliary iminodiacetic acid (HIDA) scan scintigraphy is a nuclear medicine scan used to evaluate patients suspected of having acute cholecystitis (infection/inflammation of the gallbladder). Because it is an indirect test that looks for obstruction of the cystic duct structure, there are many causes for a false-positive HIDA study. There is a need for a more sensitive and specific test that can accurately assess gallbladder infection and/or inflammation. The purpose of this study is to determine the effectiveness of fluorodeoxyglucose (FDG) as a direct means of detecting patients with acute cholecystitis. FDG is an imaging agent that has previously been shown to accumulate in areas of infection and/or inflammation. The location and intensity of FDG accumulation in the body can be detected with a camera system called a "positron emission tomography" (PET) camera. In theory, this test should be effective in detecting acute infection and/or inflammation of the gallbladder. Consenting participants will receive injection of FDG one hour prior to the FDG-PET/CT examination. The participant will then be imaged using a PET/CT machine, which is a special camera system that is capable of performing both a PET and CT scan at the same time. A CT scan is an anatomical imaging test and, for this research study, will mainly be used to localize the area of 18FDG accumulation recorded by the PET scan. The examination will take approximately one hour.

19 patients with suspected acute cholecystitis and a positive HIDA will be included in the study. This is purposely a highly selective population which most likely will have surgical proof of the findings. Subjects will receive an FDG PET/CT exam to determine the presence of gallbladder inflammation/infection(cholecystitis). Please note that 18FDG is an FDA approved radiopharmaceutical.

Sensitivity and Specificity of FDG PET/CT and Tc99mHIDA in the Evaluation of Subjects Suspected of Cholecystitis

Percent of patients identified of having cholecystitis using FDG PET/CT compared to patients identified of having pathological diagnosis of cholecystitis (sensitivity) Percent of patients identified of not having cholecystitis using FDG PET/CT compared to patients identified of not having pathological diagnosis of cholecystitis (specificity) number of false positives = number of patients incorrectly identified of having cholecystitis using FDG PET/CT compared to a negative pathological diagnosis. number of false negatives = number of patients incorrectly identified of not having cholecystitis using FDG PET/CT compared to a positive pathological diagnosis. number of true positives = number of patients correctly identified of having cholecystitis using FDG PET/CT compared to a positive pathological diagnosis. number of true negatives = number of patients correctly identified of not having cholecystitis using FDG PET/CT compared to a negative pathological diagnosis.

Inclusion Criteria: known or high suspicion of cholecystitis highly likely to undergo cholecystectomy positive HIDA study age >18 years old provide written informed consent Exclusion Criteria: highly unlikely to proceed to surgery or biopsy received an investigational drug within the past 30 days pregnant or lactating decline to provide written informed consent