CT features of ulcerative colitis and Crohn's disease.
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Biomedical subjects
Publications and source records attributed to R M Gore.
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Definitive diagnosis of infectious or idiopathic inflammatory bowel disease ultimately rests on histologic and bacteriologic documentation. Nevertheless, radiologic studies play an important role in the evaluation and management of patients with acute enterocolitis. Plain abdominal films can give a gross estimate of disease extent in the colon and detect complications, such as perforation or toxic megacolon. Double-contrast barium enema allows visualization of the mucosal pattern and the overall configuration of the bowel, which are important for determining the extent and severity of disease and its most likely cause. Cross-sectional imaging depicts the mural and mesenteric involvement as well as intraperitoneal complications of inflammatory bowel disease, thus providing a critically important perspective that complements the information afforded by endoscopic and conventional radiographic techniques.
PURPOSE: To determine whether colitides can be differentiated based on computed tomographic (CT) features. MATERIALS AND METHODS: The CT scans of 117 patients with documented colitis and colon wall thickening were reviewed. Features evaluated included mural thickness and homogeneity, distribution of bowel involvement, and associated mesenteric and small bowel disease. RESULTS: The mean colon wall thickness in Crohn colitis (11.0 mm +/- 5.1) was significantly greater than in ulcerative colitis (7.8 mm +/- 1.9) (P < .002). Submucosal fat deposition, not observed in the acute colitides, was present significantly more often in ulcerative (61%) than in Crohn colitis (8%) (P = .0001). Exclusive involvement of the right colon and small bowel was most frequent with Crohn and infectious colitis. Abscess was associated almost exclusively with Crohn colitis (35%) but was seen in one patient with radiation colitis. CONCLUSION: Although many CT findings in patients with colitis are nonspecific, some features are helpful in suggesting a specific diagnosis.
Passive hepatic congestion is caused by stasis of blood within the liver parenchyma due to compromise of hepatic venous drainage. It is a common complication of congestive heart failure and constrictive pericarditis, wherein elevated central venous pressure is directly transmitted from the right atrium to the hepatic veins because of their close anatomic relationship (Fig. 1). The liver becomes tensely swollen as the hepatic sinusoids dilate and engorge to accommodate the backflow of blood. A variety of structural and functional hepatic derangements develop that have distinctive appearances on sonograms, CT scans, and MR images.
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The kidneys in patients with acquired immunodeficiency syndrome (AIDS) are subject to a variety of insults. Renal manifestations can be seen with imaging studies of AIDS patients. Computed tomographic (CT) and ultrasound (US) scans of 64 patients with AIDS and renal dysfunction were retrospectively reviewed and compared with clinical, laboratory, and, when available, biopsy results. Imaging abnormalities included increased cortical echogenicity, nephromegaly, pyelonephritis, lobar nephronia, focal masses caused by abscess and lymphoma, parenchymal calcification, hydronephrosis, and infarct. Generally, patients with AIDS as a result of intravenous drug abuse and those with multiple risk factors were more likely to have abnormalities demonstrated at imaging as well as poorer prognosis than were patients in the homosexual transmission group in this series. Although US should be the screening study used in patients with AIDS and suspected renal dysfunction, CT and magnetic resonance imaging may be necessary to identify focal infectious, ischemic, and neoplastic processes.
Appendices epiploicae are adipose structures protruding from the serosal surface of the colon. They can be seen with abdominal radiography and cross-sectional imaging if the colonic wall is surrounded by intraperitoneal contrast material, ascites, or blood. Normal appendices epiploicae appear as lobulated masses of pericolic fat, usually 2-5 cm long and 1-2 cm thick. Their enlargement, deformity, or altered radiopacity may result from various pathologic processes that can originate locally or extend from adjacent viscera. In a series of 22 cases, appendices epiploicae were affected by spontaneous torsion and hemorrhagic infarct, calcification due to aseptic fat necrosis, primary or secondary inflammation, enlargement by lipomas or metastases, and incarceration in hernias. Disorders of appendices epiploicae are often manifested by nonspecific clinical signs and symptoms (eg, torsion is often mistaken for appendicitis or diverticulitis). These entities should be included in the differential diagnosis of any unexplained abdominal pain or pericolic lesions in adults.
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Excess hepatic iron deposition was found in five of 15 (33%) renal transplant patients undergoing magnetic resonance (MR) screening for avascular necrosis of the femoral heads. Only one of these patients had overt liver disease. The number of prior blood transfusions was a significant factor for this deposition, whereas the age and sex of the patients, number and type of transplants, histocompatibility alleles (HLA), and years of hemodialysis and of chronic renal failure were not significant etiological factors. Liver/fat intensity ratios of less than 0.29 on T1-weighted images and ratios of less than 0.21 on T2-weighted images and a calculated T2 value of less than 35 ms were the best indicators of iron overload. Renal transplant patients are at great risk for excess hepatic iron deposition and MR imaging is a promising tool for the diagnosis of iron overload in this patient population.
Seven patients with duodenal diverticulitis were evaluated by computed tomography (CT) and various other abdominal imaging techniques. The series included four men and three women who ranged in age from 47 to 84 yr (mean: 65 yr). They had presented with epigastric or periumbilical pain, low-grade fever, leukocytosis, and loss of appetite and weight due to postprandial cramps or vomiting. In each instance, the abdominal CT examination proved crucial in the diagnosis of duodenal diverticulitis, with contained perforation or inflammatory changes involving the adjacent structures. Five patients underwent laparotomy while two others were treated conservatively with antibiotics and/or percutaneous drainage of peridiverticular abscess. The clinical and radiological features of this uncommon entity are herein described, along with a brief review of the medical literature regarding the current approach to its diagnosis and management.
Topographic relationships among the gallbladder, liver, hepatic flexure of the colon, right hemidiaphragm, and anterolateral peritoneal reflection were evaluated with computed tomography in 75 patients with biopsy-proved cirrhosis and in 200 control subjects to determine the effect of cirrhotic liver morphology on the anatomy of the right upper quadrant of the abdomen. Interposition of the colon between the liver and anterolateral abdominal wall and/or diaphragm was seen in 18 of the 75 (24%) cirrhotic patients and in six of the 200 (3%) control subjects. There was a strong correlation among gallbladder malposition, colonic interposition, and a ratio of transverse caudate lobe width to right lobe width (C/RL) exceeding 0.60. Patients with cirrhosis, colonic interposition, and gallbladder malposition had a mean C/RL of 0.62, compared with a mean of 0.50 for cirrhotic patients without interposition (P less than .0001). The mean C/RL for control subjects without interposition was 0.43, as compared with 0.69 for control subjects with interposition (P less than .01). These acquired malpositions of the colon and gallbladder may pose a diagnostic dilemma and increase the risk of inadvertent injury during percutaneous liver biopsy, interventional biliary tract procedures, and laparotomy.
Computed tomography (CT) provides an important perspective in patients with inflammatory bowel disease that often has a profound influence on the therapeutic decision-making process. By virtue of its ability to image the bowel wall, serosa, and mesentery directly and noninvasively, CT can diagnose infectious and inflammatory complications that often can only be inferred indirectly by barium studies and endoscopy.
Over 3 million abdominal operations are performed in the United States each year, and a significant number of these patients subsequently undergo computed tomography (CT) either for follow-up of resected lesions or evaluation of possible postoperative complications. This article describes the clinical presentations and CT features of commonly encountered postsurgical complications. A wide spectrum of lesions involving the abdominal wall as well as intraperitoneal structures is herein illustrated to emphasize the role of CT in their diagnosis and management.
Fourteen patients had mesenteric, portal, or splenic venous thrombosis that was diagnosed primarily by contrast-enhanced CT. The group included five patients with coagulopathy, three with pancreatic carcinoma, two with cirrhosis and portal hypertension, one with pancreatitis, and one with hepatocellular carcinoma. In two patients, no etiology was determined. In all cases, CT easily identified low-density venous thrombosis, which frequently involved more than one vein. In four patients, all three splanchnic veins were involved; five patients had occlusion of two veins. In five patients, only one vein was involved. Additional CT findings included ascites, collateral veins, hepatomegaly, and splenomegaly. No venous wall enhancement was found. CT also was helpful in defining the cause of thrombosis in six of 14 patients. Mesenteric edema and/or bowel wall thickening was not identified. None of the patients had classic clinical evidence of splanchnic venous occlusion, and none died primarily of that disease. The major morbidity suffered by these patients stemmed from complications of splanchnic venous occlusion, and nine patients ultimately required sclerotherapy, splenectomy, and portal decompression. We conclude that CT is useful in the diagnosis of splanchnic venous thrombosis. Our experience suggests that mesenteric, splenic, and/or portal venous thrombosis may occur more commonly than has been previously thought and that the disease in many cases is not life threatening.
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CT scans were obtained in 17 patients who had biopsy-proved chronic active hepatitis in order to evaluate deteriorating liver function and clinical status. Lymphadenopathy in the porta hepatis and/or retroperitoneum was found in 11 patients (65%), and this was the only CT indication of significant hepatic disease in six patients (35%). In three of five patients who subsequently underwent immunosuppressive therapy, serial biopsy, and CT scanning, clinical and histologic improvement in the condition of the liver were accompanied by a reduction in lymph-node size on CT. These findings suggest that abdominal adenopathy is a frequent CT finding in patients who have chronic active hepatitis and might be a useful marker in monitoring immunotherapy.