CE Credit: For CE credit, you can access the test for this article, as well as additional JNMT CE tests, online at https://www.snmmilearningcenter.org. Complete the test online no later than December 2017. Your online test will be scored immediately. You may make 3 attempts to pass the test and must answer 80% of the questions correctly to receive 1.0 CEH (Continuing Education Hour) credit. SNMMI members will have their CEH credit added to their VOICE transcript automatically; nonmembers will be able to print out a CE certificate upon successfully completing the test. The online test is free to SNMMI members; nonmembers must pay $15.00 by credit card when logging onto the website to take the test. Participants who have already taken the exam using JNM and passed cannot retake the exam.Cholescintigraphy with 99m Tc-hepatobiliary radiopharmaceuticals has been an important, clinically useful diagnostic imaging study for almost 4 decades. It continues to be in much clinical demand; however, the indications, methodology, and interpretative criteria have evolved over the years. This review will emphasize state-of-the-art methodology and diagnostic criteria for various clinical indications, including acute cholecystitis, chronic acalculous gallbladder disease, high-grade and partial biliary obstruction, and the postcholecystectomy pain syndrome, including sphincter-of-Oddi dysfunction and biliary atresia. The review will also emphasize the use of diagnostic pharmacologic interventions, particularly sincalide. Now almost 4 decades old, 99m Tc cholescintigraphy continues to be a radionuclide imaging study in much clinical demand. Its strength lies in the fact that the diagnostic information provided defines pathophysiology rather than anatomy.123 I-and 123 I-rose bengal were the first clinically useful cholescintigraphic agents; however, image quality was relatively poor (Fig. 1). 99m Tc-hepatobiliary radiopharmaceuticals began to be widely used by the early 1980s.The discovery of 99m Tc-hepatobiliary (HIDA) radiopharmaceuticals was by chance. During investigation for a cardiac imaging radiopharmaceutical, it was found that 99m Tclabeled lidocaine was not a good cardiac imaging agent but cleared through the hepatobiliary system. With chemical modification, 99m Tc-HIDA imaging agents were born. Loberg et al. reported on this in 1976 (1). Its structure is simply that of 2 lidocaine analogs bichelated to 99m Tc by iminodiacetic acid (IDA) (Fig. 2). HIDA (hepatoiminodiacetic acid) has long been used as a generic term for cholescintigraphy.Modifications of the benzene ring of the lidocaine analogs resulted in an alphabet soup of hepatobiliary radiopharmaceuticals (PIPIDA, BIDA, EIDA, DIDA, DISIDA, etc.), each with different rates of hepatic uptake and clearance. The first 99m Tc-HIDA radiopharmaceutical was approved for clinical use by the Food and Drug Administration in 1982. Dimethyl IDA (lidofenin [Technescan; Mallinckrodt]) was a major advance, but image quality and diagnostic utility were suboptimal in patients with seru...