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Gastrointestinal Imaging |
1 From the Department of Radiology, University of Pittsburgh Medical Center-Presbyterian Hospital, 200 Lothrop St, Room 4660 CHP MT, Pittsburgh, PA 15213-2582 (S.K., M.P.F., M.K.); and the Departments of Radiology (S.K., S.G.S., P.R.R.) and Medicine (P.H.S.), Brigham and Women’s Hospital, Harvard Medical School, Boston, Mass. From the 1999 RSNA scientific assembly. Received May 3, 2000; revision requested June 5; revision received July 11; accepted August 15. Address correspondence to M.P.F. (e-mail:federlemp@radserv.arad.upmc.edu).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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MATERIALS AND METHODS: Retrospective review of medical records from two university medical centers from 1994 through 1997 revealed 215 patients who had a hypercoagulable state attributed to primary or secondary APS. Abdominal CT findings in these patients were reviewed for evidence of large-vessel occlusion or visceral ischemia.
RESULTS: In 42 (19.5%) of 215 patients with APS (age range, 32–65 years; mean age, 42 years), abdominal thromboses or ischemic events were detected at CT. Twenty-two (52%) had major vascular thromboses, including those in the inferior vena cava (n = 10), portal and superior mesenteric veins (n = 7), splenic vein (n = 4), and aorta (n = 1). Thirty-six (86%) patients had abdominal visceral ischemia resulting in renal infarction (n = 22), bowel ischemia (n = 13), splenic infarction (n = 6), pancreatitis (n = 3), hepatic infarction (n = 1), and/or hepatic dysfunction with portal hypertension (n = 1). In some patients, more than one abdominal organ and/or vessel was involved.
CONCLUSION: Patients who have circulating antiphospholipid antibodies are at risk for major abdominal vascular thromboses and organ infarction. Radiologists must be familiar with this syndrome; they may be the first physicians to suggest the diagnosis on the basis of findings of unusual or recurrent sites of thrombosis, especially in young patients.
Index terms: Abdomen, CT, 70.12112, 70.12115 • Antiphospholipid syndrome, 70.659 • Arteries, thrombosis, 95.751 • Lupus erythematosus, 70.612, 80.612 • Veins, thrombosis, 95.751
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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We recently encountered several patients who had unanticipated and catastrophic abdominal ischemic events subsequently attributed to APS. Abdominal complications of APS have received relatively little attention in prior investigations (12–16). The purpose of our study was to determine the abdominal computed tomographic (CT) findings in patients with APS.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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We excluded 228 patients because they had a medical condition known to predispose a patient to hypercoagulable states, such as malignant neoplasm; sickle cell or another type of hemoglobinopathy; or protein S, protein C, or antithrombin III deficiency. Another exclusion criterion was a patient age greater than 65 years, which was used to minimize the incidence of unrelated atherosclerotic or cardiovascular disease.
Of the remaining 990 patients, 215 had a diagnosis of APS that was based on immunologic evidence of the antibodies and clinical evidence of a hypercoagulable state, with at least two of the following criteria: recurrent deep venous thrombosis, early stroke or transient ischemic attacks, recurrent spontaneous fetal abortion, and livedo reticularis (a purple mottling of the skin attributed to small-vessel thrombosis) (5).
We excluded patients in whom visceral ischemia or vascular thrombosis was suspected or confirmed by the presence of clinical criteria but who lacked CT findings that were confirmatory and available for review. We also excluded 29 patients who underwent angiography, which demonstrated major abdominal arterial or venous occlusion, but who did not undergo CT.
Of 215 patients with APS, 160 (74.4%) underwent abdominal CT, and 42 (19.5%) of 215 had both clinical and CT evidence of abdominal organ ischemia and/or major abdominal vascular occlusion.
The exact CT equipment and protocols varied somewhat between the institutions. Helical breath-hold scans through the abdomen and pelvis were obtained with a collimation of 5, 7, or 8 mm and a pitch of 1.5–1.7. Scanning delay was 70–90 seconds. All patients received orally administered contrast medium. All except four CT studies included images obtained after intravenous administration of contrast material. Contrast material–enhanced scans were obtained during the rapid bolus injection of 60% contrast material (iothalamate meglumine [Conray 60] or ioversol [Optiray 350]; Mallinckrodt Medical, St Louis, Mo) at a dose of approximately 2 milliliters per kilogram of body weight and a rate of 2.5–3.0 mL/sec. Of 42 patients with CT findings of abdominal thrombosis, 12 had occluded vessels, which were confirmed at angiography.
CT scans were reviewed retrospectively by one or more abdominal radiologists (M.P.F., S.G.S., P.R.R.) for confirmation of CT evidence of an abdominal thrombotic event. Because we were not attempting to determine the accuracy of CT or of individual readers, we did not test for interobserver variations but accepted the judgment of CT findings by one or more of the senior investigators.
Abdominal visceral infarction was diagnosed when CT findings demonstrated lesions in the liver, kidneys, or spleen that were wedge-shaped, nonenhancing, capsular-based, and sharply defined in comparison with normally enhancing parenchyma. Intestinal ischemia was diagnosed when CT findings demonstrated bowel wall thickening greater than 3 mm along with associated submucosal edema or hemorrhage, pneumatosis, mesenteric infiltration, or ileus. Clinical confirmatory evidence of bowel ischemia consisted of surgical pathologic findings (five patients), recurrence of CT findings and clinical signs of bowel ischemia (four patients), and angiographic findings (four patients). Pancreatitis was confirmed by elevation of serum amylase and lipase levels and was attributed to ischemia only if more common causes, such as biliary calculi, alcohol abuse, and hyperlipidemia, were excluded. CT signs of pancreatitis consisted of infiltration of peripancreatic fat along with gland swelling, abnormally decreased enhancement, or pseudocyst formation. Large-vessel thrombosis was diagnosed when there was CT evidence of nonenhancing luminal contents of the inferior vena cava, portal and superior mesenteric veins, splenic vein, or aorta.
In four patients who underwent only nonenhanced CT, the diagnosis of visceral infarction was based on findings of bowel wall pneumatosis or solid parenchymal hypoattenuating wedge-shaped lesions associated with capsular retraction.
We determined the age and sex of the patients meeting our inclusion criteria.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Major abdominal vascular thromboses, which were diagnosed in 22 patients on the basis of CT criteria, involved the inferior vena cava (10 patients), the portal and superior mesenteric veins (seven patients), the splenic vein (four patients), and the aorta (one patient). Six patients had major vascular thrombosis alone, while 16 had vascular thrombosis and abdominal visceral ischemia (Table).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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While abdominal complications of APS have been mentioned in prior reports, most radiologic investigations have focused on thromboembolic disease of the extremities or cerebrovascular accidents manifested as stroke or transient ischemic attack. Numerous and varied abdominal manifestations have been noted in case reports and small series (2,5,7,8,12-20), but these have provided only a limited assessment of the importance of abdominal thrombotic events in APS. Many patients in our series had multisystem thromboembolic disease, but we wished to focus on the abdominal CT manifestations because most radiologists may be less familiar with the latter.
The combination of data from two university medical centers allowed us to identify 1,218 recent cases of patients with antiphospholipid antibodies and 215 patients who had APS. As in prior reports, the majority of these patients received medical attention because of recurrent deep venous thrombosis, repeated abortion, or stroke. However, 42 (19.5%) of the patients with APS had important abdominal manifestations, sometimes as the first clinical sign of APS. Because abdominal imaging, particularly CT, is used frequently in the evaluation of abdominal pain of uncertain origin and because the abdominal visceral infarctions and major vascular occlusions can be recognized at CT, it is likely that radiologists will be the first physicians to recognize APS as the cause of symptoms in some patients.
While we diagnosed one case of aortic occlusion, most abdominal vascular occlusions were venous; these included the inferior vena cava in 10 cases and various main branches of the portal venous system in 11. These findings are consistent with those of prior reports (5–16) in which the majority of systemic and cerebrovascular occlusions were venous rather than arterial. Vascular occlusions may lead to pulmonary emboli, visceral and bowel engorgement or ischemia, or catastrophic infarction or hemorrhage (19–22).
Among the abdominal visceral manifestations of APS, renal infarction was diagnosed most often, seen in 22 (52%) of our 42 patients. Renal complications of APS, including infarction, nephrotic syndrome, and renal hypertension, have been noted by other investigators (8,9,14,18). Renal venous thrombosis, renal arterial thrombosis or stenosis, glomerular thrombosis, and renal microangiopathy are among the proposed or documented mechanisms of injury (14,18). These mechanisms are characteristic of APS and are different from those causing vasculitis that may occur in various autoimmune disorders, including SLE.
Similarly, we diagnosed six cases of splenic infarction, with massive spontaneous hemorrhage in one case, with no evidence of vasculitis noted at histopathologic examination. A similar case of spontaneous splenic rupture was reported previously (19).
Hepatic manifestations of APS include hepatic veno-occlusive disease (Budd-Chiari syndrome), hepatic infarction, and portal hypertension. One of our patients was believed to have cryptogenic cirrhosis on the basis of abnormal results of liver function tests, portal hypertension, portal venous thrombosis, and cirrhotic-appearing morphologic findings and a nodular contour of the liver at CT (Fig 2). Results of a core-needle biopsy, however, revealed no evidence of cirrhosis or chronic hepatitis, and the hepatic pathologic changes were attributed to ischemic injury and chronic veno-occlusive disease. Our case of hepatic infarction was also unusual because infarction usually results from occlusion or compromise of both the hepatic arterial and portal venous supplies. We documented CT evidence of portal venous thrombosis but did not recognize arterial occlusion. APS should be considered as a possible cause of cryptogenic liver failure and veno-occlusive disease (Budd-Chiari syndrome) (13).
Three of our patients underwent CT and had clinical evidence of pancreatitis without a history of alcohol abuse or gallstones, and similar cases have been attributed to APS in prior reports (21,22). We also encountered 13 patients with bowel ischemia in addition to one patient who underwent total colectomy due to infarction, without imaging evaluation. In sporadic case reports (12,15, 23–26), ischemic injury of all parts of the gastrointestinal tract—including esophageal necrosis with perforation, gastric ulceration, small-bowel and colonic infarction, mesenteric and omental infarction, and acalculous cholecystitis—has been attributed to APS.
Provenzale et al (27) have reported adrenal hemorrhage and infarction in several patients with APS, although we had no similar cases in our study.
Sixteen of our 42 patients had multiple and concurrent abdominal and extraabdominal thrombotic events. Vascular thromboses tend to recur in patients with APS, and arterial thromboses may tend to recur, while venous thromboses are often followed by other venous thromboses (8,17). A rapid succession of thromboembolic events within a short interval has been labeled catastrophic occlusive syndrome (20,21,28) and may have severe or even fatal consequences. This severe manifestation of APS may be mistaken for sepsis, thrombotic thrombocytopenic purpura, or disseminated intravascular coagulation. A distinguishing feature is the absence of consumption coagulopathy in APS (28).
Among 215 patients identified as having APS, we found imaging evidence of abdominal involvement in 42 (19.5%). This percentage is likely to be an underestimation of the true prevalence because those patients with abdominal involvement not documented at CT would not have been included in our results. It is also likely that many patients with abdominal infarcts and vascular thromboses never receive a correct diagnosis of APS at CT or on the basis of clinical criteria, either because abdominal ischemia is not recognized or because it is attributed to other causes, such as vasculitis or atherosclerotic disease. In addition, abdominal visceral infarcts, particularly hepatic and splenic infarcts, may vary in their CT appearance, as illustrated by our patients (Figs 1, 2).
The retrospective nature of our study design did not allow us to calculate or report the sensitivity, specificity, or accuracy of CT in the diagnosis of abdominal manifestations of APS. Various inflammatory conditions of the bowel or of abdominal viscera may be indistinguishable from ischemic injuries on the basis of CT criteria. Demonstration of certain CT features, such as thrombosis of medium to small vessels, is clearly dependent on CT technique, including bolus intravenous injection of contrast medium and rapid acquisition of thin sections during suspended respiration.
We conclude that major abdominal vascular thromboses and visceral infarctions are prominent features of APS. Recurrent or concurrent vascular thromboses, especially venous thromboses, are characteristic of APS, and any abdominal organ or structure may be affected, alone or in combination. Recognition of multiorgan ischemia or major vascular thrombosis, particularly in a young to middle-aged patient, may allow the radiologist to suggest APS as a cause, which can be confirmed with serologic and clinical evaluation.
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FOOTNOTES |
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Author contributions: Guarantors of integrity of entire study, S.K., M.P.F.; study concepts and design, M.P.F.; definition of intellectual content, M.P.F.; literature research, S.K., M.P.F.; clinical studies, all authors; data acquisition, all authors; data analysis, S.K., M.P.F.; manuscript preparation, all authors; manuscript editing and review, M.P.F.; manuscript final version approval, all authors.
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REFERENCES |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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