27 Imaging of Biliary Disorders: Cholecystitis, Bile Duct Obstruction, Stones, and Stricture Jose C. Varghese, Brian C. Lucey, and Jorge A. Soto I. What is the best imaging strategy for the diagnosis of acute calcu- Issues lous cholecystitis? A. Ultrasonography B. Cholescintigraphy C. Computed tomography D. Magnetic resonance imaging E. Imaging strategy II. What is the best imaging strategy for the diagnosis of acute acal- culous cholecystitis? A. Ultrasonography B. Cholescintigraphy C. Computed tomography D. Imaging strategy III. What is the best imaging strategy for the diagnosis of chronic cal- culous cholecystitis? A. Ultrasonography B. Cholescintigraphy C. Imaging strategy IV. What is the best imaging strategy for the diagnosis of chronic acal- culous cholecystitis? A. Ultrasonography B. Cholescintigraphy C. Endoscopic retrograde cholangiopancreatography D. Imaging strategy V. What is the best imaging strategy for the evaluation of bile duct obstruction? A. Ultrasonography B. Computed tomography C. Magnetic resonance cholangiopancreatography D. Endoscopic ultrasonography 493 494 J.C. Varghese et al. VI. What is the best imaging strategy for the diagnosis of choledo- cholithiasis? A. Ultrasonography B. Computed tomography C. Endoscopic retrograde cholangiopancreatography D. Magnetic resonance cholangiopancreatography E. Endoscopic ultrasonography F. Imaging strategy VII. What is the best imaging strategy for the evaluation of bile duct stricture? A. Ultrasonography B. Computed tomography C. Endoscopic retrograde cholangiopancreatography D. Magnetic resonance cholangiopancreatography E. Endoscopic ultrasonography F. Special case: Klatskin tumor G. Imaging strategy Key Points ᭿ Cholescintigraphy is significantly more accurate than ultrasonogra- phy in the diagnosis of acute calculous cholecystitis (strong evidence). ᭿ There is no one highly accurate test for the diagnosis of acute acal- culous cholecystitis (moderate evidence). ᭿ Cholecystokinin stimulated cholescintigraphy is very helpful in the diagnosis of chronic acalculous cholecystitis, and is predictive of symptom relief after cholecystectomy (strong evidence). ᭿ Magnetic resonance cholangiopancreatography (MRCP) and endo- scopic ultrasonography (EUS) are superior to ultrasonography in visualizing the whole of the bile duct, and establishing the level of bile duct obstruction (strong evidence). ᭿ Patients with a high likelihood of choledocholithiasis based on clini- cal, laboratory, and ultrasonography findings should proceed directly to therapeutic endoscopic retrograde cholangiopancreatography without further cholangiographic studies (strong evidence). ᭿ Magnetic resonance cholangiopancreatography is useful in the diag- nosis of bile duct obstruction and in directing further patient man- agement (moderate evidence). ᭿ Endoscopic ultrasound and MRCP have a complementary role in the comprehensive evaluation of patients with bile duct stricture (mod- erate evidence). Definition and Pathophysiology Acute cholecystitis is caused by chemical or bacterial inflammation of the gallbladder leading to mucosal ulceration, wall edema, and fibrinosuppu- rative serositis. In up to 90% of patients, gallstones are associated and lead to acute calculous cholecystitis (ACC). In the remaining 10% of patients, gallbladder inflammation occurs in the absence of stones and results in Chapter 27 Imaging of Biliary Disorders 495 acute acalculous cholecystitis (AAC). Repeated episodes of subacute gall- bladder inflammation lead to chronic cholecystitis. Pathologically, the gall- bladder is shrunken and fibrotic with a thickened wall. Gallbladder stones are associated in 95% of these patients leading to chronic calculous chole- cystitis (CCC). In the remaining minority of patients, chronic cholecystitis occurs in the absence of gallstones resulting in chronic acalculous cholecystitis (CAC). Extrahepatic bile duct obstruction can result from intramural, mural, or extramural lesions of the biliary tract. The major causes of obstruction are stones, tumor, and benign strictures. Of these, choledocholithiasis is by far the commonest cause, accounting for up to 90% of bile duct obstruction. Bile duct strictures can be due to benign or malignant causes. Malignant lesions causing obstruction includes primary neoplasms of the bile ducts such as cholangiocarcinoma, and neoplasms extrinsic to the bile ducts. Most benign strictures of the bile duct are traumatic, infective, or inflam- matory in origin. Epidemiology Approximately 25 million (10% to 20%) adults in the United States have gallstones. They occur far more commonly in women than men, with around 40% of women greater than 80 years of age having gallstones. Prevalence is high in fair-skinned people of northern European descent, but is highest in specific races such as the Pima Indians (up to 75%). It is least prevalent in African Americans, unless there is underlying genetic disorders such as sickle cell disease or thalassemia. Acute cholecystitis typically occurs in women of reproductive age of 30 to 50 years. Chronic cholecystitis also occurs more frequently in women of the same age group. Although traditionally considered a disease of adults, cholecystitis is increasing in incidence in the pediatric population over the last 20 years with 1.3 pediatric cases occurring for every 1000 adult cases. The prevalence is increased in children with chronic hemolysis such as hemolytic anemia. Up to 5% of all cholecystectomies are performed in the pediatric age group for this reason. Acute acalculous cholecystitis occurs most commonly in hospitalized patients with severe underlying medical and surgical illness. There is no racial predilection. It occurs more commonly in males with a male-to- female ratio of 2–3:1, and occurs at an average age of over 50 years. It is more frequent in the pediatric population compared to adults. In the pedi- atric population, prognosis is good due to earlier diagnosis and treatment with cholecystectomy. The incidence of biliary obstruction in the United States is approximately 5 cases per 1000 people, with gallstones being by far the commonest cause. However, the vast majority of patients with gallstones are asymptomatic, with only 20% presenting with related symptoms. Malignancy is the second commonest cause of biliary obstruction with cholangiocarcinoma (0.1% to 0.9%), and tumors of the surrounding organs (gallbladder, pan- creas, malignant nodes) being the commonest lesions. Benign strictures of the extrahepatic bile duct are the third commonest cause of bile duct obstruction with traumatic, infective, and inflammatory lesions being the leading causes. 496 J.C. Varghese et al. Overall Cost to Society Due to the high incidence of cholecystitis and the large number of chole- cystectomies performed annually in the U.S., a sizable portion of health care costs is devoted to treating this condition. In addition, 15% of 500,000 cholecystectomies performed in the U.S. each year require common bile duct exploration (75,000), further increasing the surgical costs. The advent of laparoscopic surgery has served to reduce some of these costs, although due to the large volume of cases the health economic burden still remains high. There is very little information on the cost of managing patients with bile duct obstruction, particularly that due to malignancy. Only the minor- ity of patients undergoes curative surgery. The majority is palliated with stent placement or chemoradiotherapy. Goals The goals of imaging in gallbladder disease are (1) to diagnose gallstones, and (2) to identify underlying gallbladder disease (acute or chronic chole- cystitis) that requires treatment. The goals of imaging in patients with sus- pected bile duct obstruction are (1) to confirm the presence of obstruction, (2) to determine the level of obstruction, and (3)to diagnose the cause of obstruction. Methodology A search of the Medline/PubMed (National Library of Medicine, Bethesda, Maryland) was performed using a single or combination of key words including imaging, ultrasonography, computed tomography, magnetic resonance cholangiopancreatography, cholescintigraphy, endoscopic ultrasound, endoscopic retrograde cholangiopancreatography, acute cholecystitis, acalculous cholecystitis, chronic cholecystitis, sphincter of Oddi dysfunction, bile duct obstruction, chole- docholithiasis, neoplasm, and stricture. Reviewing the reference list of rele- vant papers identified additional articles. No time limits were applied for the searches, which were repeated up to several times up to April 16, 2004. Limits included English-language, abstracts, and human subjects. A search of the National Guideline Clearinghouse at www.guideline.gov was also performed. I. What Is the Best Imaging Strategy for the Diagnosis of Acute Calculous Cholecystitis? Summary of Evidence: Ultrasonography is useful primarily for the diagno- sis of gallstones, and secondarily in the diagnosis of acute cholecystitis. Its accuracy for diagnosis of cholelithiasis is over 95%, but its accuracy for diagnosis of acute cholecystitis is reduced to around 80%. Cholescintigra- phy is the most accurate test for the diagnosis of acute cholecystitis with an accuracy exceeding 90% (strong evidence). However, in the appropri- ate clinical setting, sonographic findings of gallstones and specific gall- bladder changes are sufficient for management of most patients with Chapter 27 Imaging of Biliary Disorders 497 suspected ACC. Cholescintigraphy should be performed where doubt exists. Supporting Evidence: Patients with