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    23204995 23204995 Document Transcript

    • Section IX – Gastrointestinal Radiology Figure 1 213. You are shown a contrast-enhanced CT of a 62-year-old man with left lower quadrant abdominal pain (Figure 1). What is the MOST LIKELY diagnosis? A. Omental infarct B. Diverticulitis C. Mesenteric panniculitis D. Epiploic appendagitis 1 Diagnostic In-Training Exam 2006
    • Section IX – Gastrointestinal Radiology Question #213 Rationales: A. Incorrect. Omental infarct is usually right sided, presenting as a large fat-containing mass centered in the omentum. It may or may not be adjacent to the colon. It is typically larger than the fatty mass of epiploic appendagitis and is less well defined. B. Incorrect. Diverticulitis demonstrates marked colonic wall thickening in addition to the surrounding inflammatory changes in the fat. It occurs more commonly in the sigmoid colon. C. Incorrect. Mesenteric panniculitis is an idiopathic, chronic, nonspecific process usually presenting as a solitary mass of heterogeneous fat at the root of the jejunal mesentery. There are often shotty lymph nodes. D. Correct. Epiploic appendagitis presents with a paracolonic fat-containing mass with well circum- scribed hyperattenuating rim (“ring sign”) and central engorged/thrombosed vessel. It is located adjacent to the left colon in most cases and is typically smaller, more round, and better defined than omental infarction. 2 American College of Radiology
    • Section IX – Gastrointestinal Radiology Figure 2A Figure 2B 3 American College of Radiology
    • Section IX – Gastrointestinal Radiology Figure 2C Figure 2D 214. You are shown T2-weighted and pre- and post-contrast T1-weighted arterial and portal venous phase MR images (Figures 2A through 2D). Concerning the hepatic lesion, which one is TRUE? A. It is the most common benign hepatic neoplasm. B. It may increase in size with use of oral contraceptives. C. It is associated with cirrhosis and viral hepatitis. D. Predisposing conditions include primary sclerosing cholangitis. 4 Diagnostic In-Training Exam 2006
    • Section IX – Gastrointestinal Radiology Question #214 Rationales: A. Incorrect. The images demonstrate typical findings of focal nodular hyperplasia, the second most common benign hepatic neoplasm. Hemangioma is the most common. B. Correct. C. Incorrect. Hepatocellular carcinoma typically occurs in the setting of cirrhosis or chronic hepatitis. D. Incorrect. These are associated with intrahepatic cholangiocarcinoma. 5 American College of Radiology
    • Section IX – Gastrointestinal Radiology Figure 3 215. You are shown a spot view of the distal ileum (Figure 3) from a small bowel series in a 48-year- old man. What is the MOST LIKELY diagnosis? A. “Backwash ileitis” of ulcerative colitis B. “Pipestem bowel” of strongyloides infection C. Tuberculosis D. Crohn’s ileitis 6 American College of Radiology
    • Section IX – Gastrointestinal Radiology Question #215 Rationales: A. Correct. The terminal ileum shows loss of mucosal folds and diffuse subtle nodularity with no ulceration or stricture. The ileocecal valve is gaping, but the ileocecal angle is preserved. The cecum is normal contour and shows diffuse superficial ulceration. These findings are characteristic of back- wash ileitis of ulcerative colitis. B. Incorrect. Strongyloides stercoralis infection is more common in the jejunum, with mucosal fold effacement and areas of narrowing. C. Incorrect. Tuberculosis of the ileum shows ulceration and hypertrophic changes. The mucosal folds first thicken and then become effaced. Though the ileocecal valve is widely patent, this is usually accompanied by loss of the ileocecal angle and shrinkage of the cecum (“coned cecum”). D. Incorrect. Crohn’s disease involving this much ileum is unlikely to be this homogeneous. It is more likely to show ulceration, more pronounced nodularity, stenosis, and eccentric bowel involvement. 7 Diagnostic In-Training Exam 2006
    • Section IX – Gastrointestinal Radiology Figure 4 216. You are shown a contrast-enhanced CT (Figure 4) of an elderly woman with chronic right upper quadrant pain. What is the MOST LIKELY diagnosis? A. Acute calculous cholecystitis B. Traumatic gallbladder rupture C. Gallbladder carcinoma D. Adenomyomatosis 8 American College of Radiology
    • Section IX – Gastrointestinal Radiology Question #216 Rationales: A. Incorrect. The CT scan demonstrates a gallstone with rim calcification in the gallbladder. There is abnormal gallbladder wall thickening. The gallbladder pathology is complicated by contiguous involvement of the adjacent hepatic parenchyma, but this appears more extensive than pericholecys- tic inflammatory changes. Acute calculous cholecystitis is a consideration in this case, but the absence of fever and an elevated WBC makes this diagnosis unlikely. B. Incorrect. Blunt abdominal trauma can cause gallbladder perforation or avulsion of the cystic duct. A traumatic perforation can result in either an intrahepatic or extrahepatic biloma. By CT, a biloma appears as a homogeneous, low-density, thin-walled, round to oval to lobulated collection. Fig. 3 does not show a discrete fluid collection typical of a biloma. In addition, no history of trauma is given. C. Correct. Rationale: Gallbladder carcinoma is the most common cancer of the biliary tree. It is asso- ciated with cholelithiasis in 60 – 90% of cases. Gallbladder cancer is three times more common in women than in men, and it most often occurs in the eighth decade of life. Contiguous spread of neo- plasm into the adjacent liver is common. This usually obviates curative surgery. As a result, the five- year survival is only 3%. D. Incorrect. Adenomyomatosis is a benign disorder of the gallbladder mucosa and muscular wall. It has two pathologic components that contribute to imaging findings. Intramural diverticula (Rokitansky-Aschoff sinuses) can appear as small hypoechoic spaces or can be filled with choles- terol crystals appearing as small echogenic foci with comet-tail acoustic artifact. Wall thickening can be circumferential (waist-like), diffuse, or focal. Focal adenomyomatosis usually occurs in the fundus and cannot be differentiated from a polypoid gallbladder carcinoma. However, because ade- nomyomatosis is benign, gallbladder wall disruption with contiguous invasion of the liver would not be expected. 9 Diagnostic In-Training Exam 2006
    • Section IX – Gastrointestinal Radiology Figure 5A 217. You are shown two images from an upper gastrointestinal examination (Figures 5A and 5B). What is the MOST LIKELY diagnosis? A. Adenocarcinoma B. Lymphoma C. Marginal ulcer D. Gastric remnant cancer 10 American College of Radiology
    • Section IX – Gastrointestinal Radiology Figure 5B 11 Diagnostic In-Training Exam 2006
    • Section IX – Gastrointestinal Radiology Question #217 Findings: There is a large benign ulcer in the efferent limb of the patient’s gastrojejunostomy. Rationales: A. Incorrect. This is a benign ulcer without any evidence of a malignant mass. B. Incorrect. Lymphoma would typically have a large mass and/or enlarged distorted folds. C. Correct. This is a classic benign appearing marginal ulcer post subtotal gastrectomy with a Billroth II anastomosis. D. Incorrect. A gastric stump cancer occurs in the stomach, not in the jejunum. 12 American College of Radiology
    • Section IX – Gastrointestinal Radiology Figure 6A Figure 6B 13 American College of Radiology
    • Section IX – Gastrointestinal Radiology Figure 6C 218. You are shown a contrast-enhanced CT (Figures 6A through 6C) in a 46-year-old woman. What is the MOST LIKELY diagnosis? A. Metastatic ovarian carcinoma B. Post-traumatic splenosis C. Polysplenia D. Lymphoma 14 Diagnostic In-Training Exam 2006
    • Section IX – Gastrointestinal Radiology Question #218 Findings: Multiple splenic masses in left upper quadrant, no intrahepatic inferior vena cava, and an enlarged azygous vein and hemiazygous vein. Rationales: A. Incorrect. The multiple masses could represent enhancing metastases but other findings make the diagnosis. B. Incorrect. There are too many splenic masses for splenules. C. Correct. Multiple splenic masses, no intrahepatic IVC and an enlarged azygous vein. D. Incorrect. There are no enlarged lymph nodes. 15 American College of Radiology
    • Section IX – Gastrointestinal Radiology Concerning gastric lymphoma, which one is TRUE? 219. A. Accounts for 25% of all gastrointestinal lymphomas B. Vast majority are Hodgkin’s lymphoma C. Low-grade MALT lymphomas usually present as large bulky masses on upper gastrointestinal barium studies D. Advanced gastric lymphoma is usually large and involves the body and antrum Question #219 Rationales: A. Incorrect. Lymphoma involves the stomach more frequently than any other portion of the gastroin- testinal tract and accounts for 50% of all gastrointestinal lymphomas. B. Incorrect. Almost all gastric lymphomas are non-Hodgkin’s lymphoma of B-cell origin. C. Incorrect. Low-grade MALT lymphomas usually present as varied sized, rounded nodules on double contrast barium studies. D. Correct. Advanced lymphoma is a large bulky mass and most commonly involves the gastric body and antrum. 16 American College of Radiology
    • Section IX – Gastrointestinal Radiology Concerning gastrojejunostomy, which one of the following is TRUE? 220. A. A Billroth I is a gastrojejunostomy. B. A gastric stapling procedure incorporates a Roux-en-Y loop. C. Internal hernias occur in up to 5% of patients following gastric bypass for weight reduction. D. There is no increased risk for gastric cancer following partial gastrectomy for benign peptic ulcer disease. Question #220 Rationales: A. Incorrect. A Billroth I is an antrectomy with a gastroduodenostomy. B. Incorrect. A gastric partitioning stapling does not use any type of gastro-jejunal anastomosis. C. Correct. Internal hernias have been reported in up to 5% of post gastric bypass operations. D. Incorrect. There is a 3 to 6 fold increased chance of developing gastric remnant adenocarcinoma 15 to 20 years following surgery for benign peptic ulcer disease. 17 Diagnostic In-Training Exam 2006
    • Section IX – Gastrointestinal Radiology Concerning splenic trauma, which one is TRUE? 221. A. The spleen is injured in 35% of penetrating abdominal trauma. B. The spleen is the second most common solid organ injured in blunt trauma. C. Grading splenic trauma is a reliable way to predict whether a patient will need splenectomy. D. Embolization techniques can be used to control splenic hemorrhage. Question #221 Rationales: A. Incorrect. The spleen is injured less than 10%. B. Incorrect. The spleen is the most common solid organ injured. C. Incorrect. CT and surgical grading systems are not reliable methods to predict conservative vs. sur- gical management. D. Correct. Embolization techniques can be useful in controlling splenic hemorrhage and obviating splenectomy. 18 American College of Radiology
    • Section IX – Gastrointestinal Radiology Concerning double-contrast upper GI examination, which one is TRUE? 222. A. Flow technique is useful for evaluation of the stomach but not the duodenum. B. Compression views of the duodenum are obtained in the supine position. C. The left posterior oblique view provides a double contrast view of the duodenum. D. A barium suspension of 25% W/V concentration is used. Question #222 Rationales: A. Incorrect. Flow technique is useful for evaluating superficial lesions on the dependent surface of the stomach and duodenum. B. Incorrect. Compression views of the duodenum are typically obtained in the prone position. C. Correct. D. Incorrect. A barium suspension of 250% W/V concentration is used. 19 Diagnostic In-Training Exam 2006
    • Section IX – Gastrointestinal Radiology Concerning duodenal inflammatory disease, which one is TRUE? 223. A. Duodenocolic fistulas are likely to occur in primary duodenal Crohn’s disease. B. Radiation doses of 500 rad to the duodenum may cause radiation duodenitis. C. Mucosal fold thickening is often more severe in dialysis patients. D. Duodenal caustic injury is more likely to occur with alkali ingestion than acid ingestion. Question #223 Rationales: A. Incorrect. Duodenocolic fistulas rarely occur in primary duodenal Crohn’s disease, but will occa- sionally occur in primary colonic Crohn’s disease. B. Incorrect. The dose threshold for injury is 5000 rad. C. Correct. D. Incorrect. The opposite is true. 20 American College of Radiology
    • Section IX – Gastrointestinal Radiology 224. Concerning abdominal multidetector CT (MDCT), the z-axis resolution MOST LIKELY increases with decreasing: A. slice thickness B. radiation dose C. mAs (product of tube current and scan time) D. image noise Question #224 Rationales: A. Correct. Spatial resolution in CT is dependent on the image matrix (FOV) in transaxial plane and slice thickness in z- direction. One of the driving force in MDCT is to obtain high spatial resolution and this is achieved by scanning very thin slice thickness. B. Incorrect. The radiation dose per slice in CT increases with decreasing slice thickness. This is done in order to maintain lower image noise. C. Incorrect. Decreasing mAs yeilds higher image noise and could degrade spatial resolution D. Incorrect. See correct answer. 21 Diagnostic In-Training Exam 2006
    • Section IX – Gastrointestinal Radiology Concerning selective immunoglobulin A deficiency, which one is TRUE? 225. A. It is an uncommon immunodeficiency in adults. B. The majority of persons with IgA deficiency will present with malabsorption. C. It is not associated with celiac disease. D. It carries an increased risk of malignancy. Question #225 Rationales: A. Incorrect. It is the most common immunodeficiency in adults, occurring in 1 in 700 persons. B. Incorrect. Most are asymptomatic because of a compensatory rise in IgM production. The remain- der will be symptomatic and may respond favorably to a gluten-free diet. C. Incorrect. It has been reported in 1 in 40 patients with celiac disease. D. Correct. Malignant tumors are more common in patients with IgA deficiency and in patients with other immunodeficiencies. 22 American College of Radiology
    • Section IX – Gastrointestinal Radiology 226. Concerning acute pancreatitis on a helical CT with dynamic bolus contrast enhancement, which finding is the BEST prognostic indicator of morbidity and mortality? A. Size of the pancreas B. Location and size of fluid collections C. Presence of biliary obstruction D. Pancreatic parenchymal enhancement Question #226 Rationales: A. Incorrect. While this is one of the indicators of the severity of acute pancreatitis, it is not the most predictive of M & M. B. Incorrect. While this is one of the indicators of the severity of acute pancreatitis, it is not the most predictive of M & M. C. Incorrect. While this is a complication of acute pancreatitis, it is not the most predictive of M & M. D. Correct. There is general agreement that the development and extent of pancreatic necrosis are the most important indicators of disease severity. Necrosis is diagnosed when portions of the gland do not enhance. 23 Diagnostic In-Training Exam 2006
    • Section IX – Gastrointestinal Radiology Concerning microcystic cystadenoma of the pancreas, which one is TRUE? 227. A. Fluid aspirated from the cyst will contain mucin. B. They usually appear as a solid mass on ultrasound exam. C. They should be resected because they are potentially malignant. D. They rarely calcify. Question #227 Rationales: A. Incorrect. Aspirate yields low viscosity fluid. The cysts are lined by glycogen-containing cells. Macrocystic cystadenomas and cystadenocarcinomas have mucinous fluid. B. Correct. They have this appearance because the small cysts are depicted only as acoustic interfaces. C. Incorrect. They are benign. Macrocystic adenomas are potentially malignant. D. Incorrect. Microcystic adenoma calcifies more than any other pancreatic tumor, with central calcifi- cations seen in about one-third by conventional radiographs. 24 American College of Radiology
    • Section IX – Gastrointestinal Radiology Concerning duodenal ulcers, which one is TRUE? 228. A. Free air is seen on conventional x-rays in up to 2/3 with perforation. B. Duodenal peptic ulcers have a 5% chance of being malignant. C. Multiple ulcers throughout the duodenum are most frequently associated with aspirin therapy. D. Altered mucosal resistance is a major factor in the pathogenesis of duodenal peptic ulcers. Question #228 Rationales: A. Correct. B. Incorrect. Gastric ulcers have a 5% chance of being malignant. In contrast, duodenal ulcers are vir- tually always benign. C. Incorrect. Eighty-five percent of duodenal ulcers are solitary. Multiple ulcers in the postbulbar duo- denum should raise the possibility of Zollinger-Ellison syndrome. Chronic aspirin therapy is associ- ated with multiple gastric ulcers, seen in over 80% of these patients. It is not associated with duode- nal ulcers. D. Incorrect. This is thought to be the major factor in gastric peptic ulcers. Duodenal ulcers are due to increased peptic acid secretion. 25 Diagnostic In-Training Exam 2006
    • Section IX – Gastrointestinal Radiology Concerning esophageal intramural pseudodiverticulosis, which one is TRUE? 229. A. Most commonly associated with Candida infection B. Is a pre-malignant condition C. Histologically represents dilated submucosal mucus glands D. Outpouchings range in size from 1 cm to 2 cm Question #229 Rationales: A. Incorrect. Esophageal intramural pseudodiverticulosis (EIPD) is most commonly associated with reflux disease, but can be seen in Candidiasis, stricture, or esophageal carcinoma. B. Incorrect. C. Correct. D. Incorrect. Outpouchings are usually on the order of 1 – 4 mm. 26 American College of Radiology
    • Section IX – Gastrointestinal Radiology 230. What disease is associated with mesenteric desmoid tumors? A. Gardner’s syndrome B. Carcinoid tumors C. Lymphoma D. Peritoneal mesothelioma Question #230 Rationales: A. Correct. Desmoid tumors occur predominately in patients with Gardner’s syndrome who have had abdominal surgery. B. Incorrect. Carcinoid tumors may have a similar appearance to desmoid tumors but are not associat- ed with them. C. Incorrect. No association. D. Incorrect. No association. 27 Diagnostic In-Training Exam 2006
    • Section IX – Gastrointestinal Radiology 231. For an abdominal radiograph of a very large patient, which method is MOST LIKELY to improve x-ray transmission? A. Increasing mAs B. Increasing the kVp C. Increasing the tube-patient distance D. Decreasing the tube-patient distance Question #231 Rationales: A. Incorrect. Increasing mAs will increase the number of photons generated and a proportionate num- ber of photons making it through the patient, however the photon energies and the fraction of inci- dent photons making it through the patient is unchanged. B. Correct. Increasing kVp not only increases the number of x-ray photons generated, but also pro- duces higher energy photons with a maximum photon energy in keV equal to the kVp voltage across the x-ray tube. The higher energy photons are more penetrating an a higher fraction of the incident photons will pass through the patient to the detector. C. Incorrect. Increasing the tube-patient distance for a given technique does not change the penetrating ability of the beam and will decrease the intensity of the beam. D. Incorrect. Decreasing the tube-patient distance for a given technique will increase the incident intensity of the beam, but will not change the penetrating ability of the beam. Note that decreasing the tube-patient distance can significantly increase the entrance exposure to the patient. 28 American College of Radiology
    • Section IX – Gastrointestinal Radiology 232. What is the MOST common malignant primary hepatic tumor? A. Hepatocellular carcinoma B. Lymphoma C. Focal nodular hyperplasia D. Intrahepatic cholangiocarcinoma Question #232 Rationales: A. Correct. HCC is the most common primary hepatic malignancy. B. Incorrect. Hepatic lymphoma is uncommon and often undetectable by imaging. C. Incorrect. FNH is benign. D. Incorrect. Intrahepatic cholangiocarcinoma is the second most common primary hepatic malignancy. 29 Diagnostic In-Training Exam 2006
    • Section IX – Gastrointestinal Radiology 233. Concerning jaundice, which of the following is the MOST common etiology? A. Choledocholithiasis B. Pancreatitis C. Benign stricture D. Pancreatic carcinoma Question #233 Rationales: A. Incorrect. Choledocholithiasis accounts for 20% of cases of biliary obstruction. B. Incorrect. Pancreatitis accounts for 8%. C. Correct. Benign stricture form surgery, trauma, or biliary intervention accounts for almost half of the cases of biliary obstruction. D. Incorrect. Pancreatic cancer does cause biliary obstruction, but less commonly than benign stricture. 30 American College of Radiology
    • Section IX – Gastrointestinal Radiology 234. Concerning focal hepatic fatty sparing, what is its appearance on imaging studies? A. Hypodense on CT relative to remaining liver B. Hyperechoic on US relative to remaining liver C. Demonstrates no signal loss on fat-suppressed MR images D. Heterogeneous enhancement Question #234 Rationales: A. Incorrect. Areas of fatty sparing are hyperdense. B. Incorrect. Fatty sparing is hypoechoic. C. Correct. D. Incorrect. Enhancement pattern is similar to the entire liver. 31 Diagnostic In-Training Exam 2006
    • Section IX – Gastrointestinal Radiology Concerning ADULT intussusception, which one is TRUE? 235. A. Most surgical cases are caused by a structural lesion. B. Carcinoid is the most common malignancy to cause a colocolic intussusception. C. Symptomatic intussusception is more common in adults than children. D. Asymptomatic small bowel intussusceptions commonly require surgery. Question #235 Rationales: A. Correct. In most adult cases, intussusception is associated with a bowel-related structural abnormality. B. Incorrect. About 40% of adult intussusceptions are caused by malignant neoplasms. In the colon, primary adenocarcinoma is the most common. C. Incorrect. Intussusception is most commonly a disease of childhood. Eighty-five to ninety-five per- cent of intussusceptions occur in children. Ninety-five percent of pediatric intussusceptions are idio- pathic. However, there is some evidence to suggest that viral infection causing Peyer patch enlarge- ment could be the underlying etiology in many cases. D. Incorrect. A short-segment, relatively asymptomatic or incidental enteroenteric intussusception is fre- quently noted with abdominal CT and MR in adults. These are not associated with significant small bowel obstruction, are usually self-limiting and transient, and do not require surgical intervention. 32 American College of Radiology
    • Section IX – Gastrointestinal Radiology Concerning Mirizzi syndrome, which one is TRUE? 236. A. Mirizzi syndrome is caused by gallstone impaction in the common hepatic duct. B. Mirizzi syndrome is facilitated by an anatomic variant. C. Cholecystocolonic fistula can complicate Mirizzi syndrome. D. Bile duct injury at surgery is less likely in cases of Mirizzi syndrome. Question #236 Rationales: A. Incorrect. Mirizzi syndrome is a complication of longstanding cholelithiasis. It is caused by impaction of a gallstone in the cystic duct or in the gallbladder neck. Extrinsic mass effect of the stone in the cystic duct on the common hepatic duct (CHD) or associated inflammatory changes extending to the CHD causes obstruction of the extrahepatic biliary tree B. Correct. Mirizzi syndrome is defined as extrinsic obstruction of the common hepatic duct (CHD), usually caused by mass effect from a stone lodged in the adjacent cystic duct. CHD compression is more likely in patients with low cystic duct insertions, because the cystic duct runs more parallel and in closer proximity to the CHD when this variant anatomy is present. Inflammatory changes extending from the cystic duct or gallbladder neck can also cause narrowing of the bile duct. C. Incorrect. A cholecystocholedochal (not cholecystocolonic) fistula is a complication of Mirizzi syn- drome in 9 – 39% of cases. Fistula repair is required at the time of surgery. This requires either choledochoplasty or hepaticojejunostomy. D. Incorrect. Because of adhesions, inflammation and variant bile duct anatomy, the surgical dissection is more difficult in Mirizzi syndrome. Inadvertent injury to the biliary tree or hepatic artery is more likely. Although laparoscopic cholecystectomy can be performed successfully in patients with Mirizzi syndrome, more require open cholecystectomy than in cases of uncomplicated cholecystitis. 33 Diagnostic In-Training Exam 2006
    • Section IX – Gastrointestinal Radiology Concerning intrahepatic cholangiocarcinoma, which one is TRUE? 237. A. It is usually hyperdense during the arterial phase of contrast enhancement. B. It demonstrates washout during delayed CT imaging. C. Postobstructive hepatic atrophy can be a prominent feature. D. Extrahepatic spread of intrahepatic cholangiocarcinoma is uncommon. Question #237 Rationales: A. Incorrect. In the absence of primary sclerosing cholangitis, intrahepatic cholangiocarcinoma usually presents as a bulky mass. The lesion tends to be hypodense to background liver on noncontrast CTs. Following the dynamic administration of IV contrast, intrahepatic cholangiocarcinoma tends to remain relatively hypovascular (not hyperdense), particularly centrally. B. Incorrect. Increased patchy enhancement can be observed during the portal venous phase. Retention of contrast within the extracellular space of the central stoma at delayed CT imaging (5 – 10 min- utes) is relatively characteristic for these lesions. C. Correct. High-grade obstruction from intrahepatic and hilar cholangiocarcinomas can cause atrophy of the hepatic parenchyma surrounding the pathologically dilated biliary tree. Capsular retraction occurs in about 20% of cases. This retraction likely reflects the atrophy of a small volume of hepat- ic parenchyma beneath Glisson’s capsule. Surprisingly marked segmental and lobar atrophy can occur when cholangiocarcinoma affects more central intrahepatic or hilar bile ducts. D. Incorrect. The extrahepatic spread of peripheral, intrahepatic cholangiocarcinoma is not uncommon. In autopsy series, it is noted in about 50 – 70% of cases. Metastatic disease to regional celiac and left gastric nodes occurs frequently. The prevalence of microscopic nodal disease with its tendency to spread back to the liver makes the preoperative diagnosis of cholangiocarcinoma a contraindica- tion for hepatic transplantation. 34 American College of Radiology
    • Section IX – Gastrointestinal Radiology Concerning Crohn’s disease, which one is TRUE? 238. A. In the United States, ulcerative colitis is less common than Crohn’s disease. B. Ulcerative colitis can affect any part of the alimentary tract. C. Crohn’s disease is limited to the mucosa of the gastrointestinal tract. D. Crohn’s disease does not contiguously affect the bowel. Question #238 Rationales: A. Incorrect. Among the general population of the United States, ulcerative colitis is more common than Crohn’s disease. The incidence of ulcerative colitis is 11 per 100,000. The incidence of Crohn’s disease is about 7 per 100,000. B. Incorrect. Crohn’s disease can affect any part of the gastrointestinal tract, from the mouth to the anus. About 75% of Crohn’s patients will have disease of the small intestine, without or with con- comitant disease elsewhere. Of all patients with small intestinal Crohn’s, 90% have involvement of the terminal ileum. Ulcerative colitis affects the colon. The terminal ileum can be secondarily affect- ed, backwash ileitis. C. Incorrect. Crohn’s disease is associated with transmural inflammation of the bowel wall. At histol- ogy, noncaseating granulomas can be found throughout all layers, from the mucosa to the serosa. Granulomas, lymphoid aggregates, inflammatory changes and fissures can penetrate through the bowel wall to involve the adjacent mesentery (fibrofatty change) and mesenteric lymph nodes. D. Correct. Crohn’s disease tends to have a discontinuous distribution. Lengths of involved gut will have disease free segments or “skip areas”. Crohn’s disease often spares the rectum. This contrasts with ulcerative colitis, in which the rectum is almost always involved. In ulcerative colitis, disease extends upstream from the rectum and is continuous, without intervening normal segments. 35 Diagnostic In-Training Exam 2006