CT and MR imaging findings of bowel ischemia from various primary causes

Imaging the postoperative patient: long-term complications of gastrointestinal surgery

OBJECTIVES

The objectives of this review are (1) to become acquainted with the long-term complications of surgery of the gastrointestinal tract, and (2) to appreciate the appropriate use of imaging in the assessment of long-term complications.

BACKGROUND

Gastrointestinal tract surgery comprises a group of procedures performed for a variety of both benign and malignant diseases. In the late postoperative setting, adhesions and internal hernias are the most important complications. and they can be further complicated by volvulus and ischemia. At present, computed tomography (CT) is the workhorse for evaluating late postoperative complications. Accurate imaging assessment of patients is essential for adequate treatment planning.

IMAGING FINDINGS OR PROCEDURE DETAILS

In this pictorial essay we will review the most frequent long-term complications after gastrointestinal surgery, including adhesions, afferent loop syndrome, closed-loop obstruction, strangulated obstruction, internal hernias, external hernias, anastomotic strictures and disease recurrence. Examples will be depicted using iconography from the authors' imaging department.

CONCLUSIONS

Knowledge of the most frequent complications after gastrointestinal surgery in the late postoperative period is of paramount importance for every radiologist, so that potentially life-threatening situations can be promptly diagnosed and adequate therapy can be planned.

TEACHING POINTS

• Long-term postoperative complications of gastrointestinal tract surgery can be divided into procedure-related and disease-related categories. • The most common procedure-related complications are internal hernias and adhesions. • The most frequent disease-related complications are mainly associated with neoplastic or inflammatory recurrence. • Computed tomography is the most useful examination when such complications are suspected.

Radiological Diagnosis of Portal/Mesenteric Vein Occlusion

Background

In contrast to an acute occlusion of the visceral arteries, which is the most important differential diagnosis for an occlusion of the portal venous system and which poses a highly dangerous situation ending in gangrene of the bowel wall, the symptoms of an acute occlusion of the portal venous system are quite unspecific. To rule out an acute arterial occlusion, diagnostic evaluation has to be carried out quickly in order to decide on the necessity of therapeutic steps concerning a recanalization of the occluded vessels. Only few therapeutic options are available to recanalize and remodel the portal venous system, depending on the underlying disease, the age of the occlusion, its extension, and the effect on the bowel wall, stomach, spleen, and abdominal wall. Moreover, the efficacy of recanalization procedures mainly depends on the formation and number of collateral venous blood supply, its degree, and the anatomic structure. Possible complications of portal hypertension like varices, gastrointestinal vasculopathy, ascites, and splenomegaly also influence the success of recanalization procedures. Only in cases of acute thrombotic occlusion systemic lytic therapy promises to be successful. Therefore, other options such as transjugular intrahepatic recanalization, e.g. by means of the TIPS (transjugular intrahepatic portosystemic shunt) procedure, have to be evaluated.

Methods

Review of the literature.

Results

Noninvasive methods such as ultrasound (US), computed tomography, and especially magnetic resonance imaging (MRI) allow the evaluation of therapeutic options as well as their success, the feasibility of technical procedures, the detection of possible risks, and a calculation of risks and benefits.

Conclusion

In order to arrive at the correct therapeutic decision, a combination of MRI and US methods combined with color Doppler guarantee the most efficient diagnostic results in cases with acute or chronic occlusions of the portal venous system.

Ischemic colitis: spectrum of CT findings, sites of involvement and severity

To summarize the frequency of findings on IV contrast, enhanced computer tomography (CT) in 335 patients with pathologically proven ischemic colitis (IC) determine the most frequent locations and patterns of involvement and establish the correlation of these findings with the severity of IC. 231 patients were excluded for not having a concomitant CT or for having underlying comorbidities. 104 cases were analyzed. Scans were evaluated for abnormal wall enhancement (AE), bowel wall thickening (BWT), bowel dilatation (DIL), mesenteric fat stranding (FS), venous engorgement (VE), pericolonic free fluid (FF), and pneumatosis (PN) and portomesenteric venous gas. Segmental versus pancolonic involvement was noted. Severity was determined by histopathology criteria. Data obtained are as follows: female to male incidence, 69 % (70) vs. 31 % (34); average age, 64.5; and positive CT, 102/104 (98.1 %). The most frequent findings include FS (88 %), BWT (88 %), and AE (82 %) regardless of severity of involvement. Statistically significant increased risk ratio and likelihood of severe ischemia for PN, DIL, and FF individually. BWT, DIL, FS, FF, VE, and PN together have a probability for severe IC of 91.8 %. A correlation between fewer findings and milder IC was found (R (2) = 0.6771). The most frequently involved segments: descending (64 %) and sigmoid colon (54 %). Splenic flexure (SF) was infrequently involved (n = 8, 7.84 %). Females had two times higher incidence of IC. The most frequent CT findings in IC are FS, BWT, and AE regardless of the severity. PN is suggestive of severe IC. Segmental involvement is the predominant pattern. The distal colon is more frequently involved. SF contrary to the conventional literature is not disproportionately involved in IC.

Imaging of common solid organ and bowel torsion in the emergency department

OBJECTIVE

This article will discuss the most common forms of torsion encountered in the emergency department.

CONCLUSION

Torsion refers to the twisting of an object about its axis and represents the pathophysiologic mechanism underlying an important group of disorders affecting both the bowel and the solid organs of the abdomen and pelvis. Although these disorders typically present with the acute onset of pain, clinical findings are often nonspecific, with imaging playing a key role in diagnosis. Missed or delayed diagnosis may result in complications, such as ischemia; end-organ loss; and, in some cases, death. Therefore, it is critical to have a thorough understanding of the pathophysiology and imaging findings of these entities to avoid the morbidity and mortality associated with a missed or delayed diagnosis.

Computed tomography evaluation of high-grade esophageal necrosis after corrosive ingestion to avoid unnecessary esophagectomy

BACKGROUND

Esophagectomy is the standard of care for high-grade corrosive esophageal necrosis as assessed endoscopically. However, the inaccuracy of endoscopy in determining the depth of intramural necrosis may lead to unnecessary esophageal resection, with devastating consequences. Our aim was to evaluate the use of computed tomography (CT) for the emergency diagnostic workup of endoscopic high-grade corrosive esophageal necrosis.

METHODS

In a before (2000-2007)/after (2007-2012) study of patients with grade 3b endoscopic esophageal necrosis, we compared outcomes after routine emergency esophagectomy versus selection for emergency esophagectomy based on CT evidence of transmural necrosis, defined as at least two of the following: esophageal-wall blurring, periesophageal-fat blurring, and the absence of esophageal-wall enhancement. Survival estimated using the Kaplan-Meier method was the primary outcome.

RESULTS

Compared to the routine-esophagectomy group (n = 125), the CT group (n = 72) had better overall survival in the crude analysis (hazard ratio [HR], 0.43; 95 % confidence interval [95 %CI], 0.21-0.85; P = 0.015) and in the analysis matched on gender, age, and ingested agent (HR, 0.36; 95 %CI, 0.16-0.79; P = 0.011). No deaths occurred among patients managed without emergency esophagectomy based on CT findings, and one-third of CT-group patients had their functioning native esophagus at last follow-up. Self-sufficiency for eating and breathing was more common (84 % vs. 65 %; relative risk [RR], 1.27; 95 %CI, 1.04-1.55; P = 0.016) and repeat suicide less common (4 % vs. 15 %; RR, 0.27; 95 %CI, 0.09-0.82; P = 0.019) in the CT group.

CONCLUSION

The decision to perform emergency esophagectomy for endoscopic high-grade corrosive esophageal injury should rely on CT findings.

Gastrointestinal intramural hematoma--analysis of clinical and radiological features for early differentiation from mesenteric ischemia

INTRODUCTION

Long-term anticoagulation is associated with hemorrhage at various sites. Gastrointestinal intramural bleeds and hematomas (IMH) often mimic mesenteric ischemia (MI) due to similar clinical settings and imaging features, making early differentiation difficult.

AIM

To compare the demography, clinical features and imaging characteristics of patients presenting with IMH with those of MI, so as to help in evolving clinical and imaging guidelines to differentiate both early in the course of the disease.

METHODS

All radiologically (contrast-enhanced computed tomogram [CT]) diagnosed cases of gastrointestinal IMH from the hospital database during the period between 2006 and 2012 were retrospectively analyzed. This data was compared with the clinical and imaging features of a group of surgically confirmed MI during the same period. Patients not on anticoagulation therapy at the time of presentation and those with incomplete clinical or radiological data were excluded from the study.

RESULTS

There were 16 patients in IMH group and 54 patients in MI group. Clinical features like overt rectal bleeding or melena, and prolonged prothrombin time-international normalized ratio (PT-INR) more than three, and CT features like proximal location in the bowel, increased bowel wall thickness, hyperdensity on plain scan (>40 Hounsfield units (HU)), and short segment bowel involvement were significantly associated with IMH. Visualization of embolus and absent mesenteric vasculature to a segment of intestine in CT was significantly associated with MI.

CONCLUSION

Attention to clinical features and early CT scan can aid in early differentiation of IMH from MI, facilitating appropriate intervention early in the course of disease.

Acute Mesenteric Ischaemia

Acute mesenteric ischaemia (AMI) is a surgical emergency, and has a high mortality. The term AMI covers arterial embolism, arterial thrombosis, non-occlusive mesenteric ischaemia and venous thrombosis which all lead to ischaemia/reperfusion syndrome of the bowel. Multi-detector row helical CT (MDCT) technology has dramatically improved the performance of CT by allowing rapid volumetric data acquisition to provide increased resolution, leading to better identification of the site, level and cause of ischaemia. CT angiography for diagnosing mesenteric ischaemia is now highly sensitive and specific, and should be used as first line when AMI is suspected. The aim of management is to restore intestinal blood flow in a timely manner. Therapeutic decisions are based on the presence of peritonitis, the presence of irreversible ischaemia or infarcted segments of the bowel, the general condition of the patient and the pathophysiological process underlying the ischaemia. AMI remains a challenging condition with high mortality. There is a need for good general surgical cover on the intensive care unit, with continuing care and clinical review by experienced senior surgeons with an interest in this condition.

Multi-detector CT features of acute intestinal ischemia and their prognostic correlations

Acute intestinal ischemia is an abdominal emergency occurring in nearly 1% of patients presenting with acute abdomen. The causes can be occlusive or non occlusive. Early diagnosis is important to improve survival rates. In most cases of late or missed diagnosis, the mortality rate from intestinal infarction is very high, with a reported value ranging from 60% to 90%. Multi-detector computed tomography (MDCT) is a fundamental imaging technique that must be promptly performed in all patients with suspected bowel ischemia. Thanks to the new dedicated reconstruction program, its diagnostic potential is much improved compared to the past and currently it is superior to that of any other noninvasive technique. The increased spatial and temporal resolution, high-quality multi-planar reconstructions, maximum intensity projections, vessel probe, surface-shaded volume rending and tissue transition projections make MDCT the gold standard for the diagnosis of intestinal ischemia, with reported sensitivity, specificity, positive and negative predictive values of 64%-93%, 92%-100%, 90%-100% and 94%-98%, respectively. MDCT contributes to appropriate treatment planning and provides important prognostic information thanks to its ability to define the nature and extent of the disease. The purpose of this review is to examine the diagnostic and prognostic role of MDCT in bowel ischemia with special regard to the state of art new reconstruction software.

Bowel wall thickening at CT: simplifying the diagnosis

Objective

In this article we present a simplified algorithm-based approach to the thickening of the small and large bowel wall detected on routine computed tomography (CT) of the abdomen.

Background

Thickening of the small or large bowel wall may be caused by neoplastic, inflammatory, infectious, or ischaemic conditions. First, distinction should be made between focal and segmental or diffuse wall thickening. In cases of focal thickening further analysis of the wall symmetry and perienteric anomalies allows distinguishing between neoplasms and inflammatory conditions. In cases of segmental or diffuse thickening, the pattern of attenuation in light of clinical findings helps narrowing the differential diagnosis.

Conclusion

Focal bowel wall thickening may be caused by tumours or inflammatory conditions. Bowel tumours may appear as either regular and symmetric or irregular or asymmetric thickening. When fat stranding is disproportionately more severe than the degree of wall thickening, inflammatory conditions are more likely. With the exception of lymphoma, segmental or diffuse wall thickening is usually caused by benign conditions, such as ischaemic, infectious and inflammatory diseases.

Key points

• Thickening of the bowel wall may be focal (<5 cm) and segmental or diffuse (6-40 cm or >40 cm) in extension.

• Focal, irregular and asymmetrical thickening of the bowel wall suggests a malignancy.

• Perienteric fat stranding disproportionally more severe than the degree of wall thickening suggests an inflammatory condition.

• Regular, symmetric and homogeneous wall thickening is more frequently due to benign conditions, but can also be caused by neoplasms such as well-differentiated adenocarcinoma and lymphoma.

• Segmental or diffuse bowel wall thickening is usually caused by ischaemic, inflammatory or infectious conditions and the attenuation pattern is helpful in narrowing the differential diagnosis.

Increased unenhanced bowel-wall attenuation at multidetector CT is highly specific of ischemia complicating small-bowel obstruction

PURPOSE

To evaluate performance of increased bowel-wall attenuation on unenhanced 64-section multidetector computed tomographic (CT) images for diagnosing bowel-wall ischemia in patients with mechanical small-bowel obstruction (SBO) and to evaluate the diagnostic accuracy of multidetector CT in detecting small-bowel ischemia complicating SBO, with surgical and histopathologic findings as reference standard.

MATERIALS AND METHODS

The local institutional review board approved this retrospective study; informed consent requirement was waived. In 44 patients (10 men, 34 women; age range, 30-100 years) who were admitted because they were suspected of having SBO and treated surgically within the next 7 days, 45 multidetector CT scans were retrospectively reviewed. Two gastrointestinal radiologists performed independent blinded reviews of images to identify specific signs of ischemia; disagreements were resolved in consensus with a third gastrointestinal radiologist. Results were compared with both findings in prospective radiology reports and surgical and histopathologic findings. Fisher exact and χ(2) tests were used to assess associations between CT signs and ischemia, and the κ statistic was used to assess interobserver agreement.

RESULTS

In 19 of 45 (42%) multidetector CT scans, ischemia was confirmed at surgery and/or histopathologic examination. Increased bowel-wall attenuation on unenhanced images was significantly associated with ischemia (P < .0001); in this highly selected population, this sign had a 100% (24 of 24) specificity and a 56% (10 of 18) sensitivity. Sensitivity and specificity of multidetector CT for ischemia were 63% (12 of 19) and 92% (24 of 26), respectively, for the prospective reports and 84% (16 of 19) and 96% (25 of 26), respectively, for the consensus review. Decreased segmental bowel-wall enhancement was the most accurate 64-section multidetector CT sign for diagnosing ischemia (sensitivity, 78% [14 of 18]; specificity, 96% [24 of 25]; P < .0001). The small-bowel feces sign was significantly associated with ischemia (P = .0308).

CONCLUSION

Increased bowel-wall attenuation on unenhanced 64-section multidetector CT images is a specific sign for ischemia complicating SBO. Diagnostic accuracy of 64-section multidetector CT for ischemia associated with SBO was excellent.

Splanchnic venous thrombosis and pancreatitis

Pancreatitis is an inflammatory process with local and systemic manifestations. One such local manifestation is thrombosis in splanchnic venous circulation, predominantly of the splenic vein. The literature on this important complication is very sparse. This review offers an overview of mechanism of thrombosis, its pathophysiology, diagnosis, and management in the setting of acute as well as chronic pancreatitis.

MDCT of abdominopelvic oncologic emergencies

Acute complications arising in abdominopelvic malignancies represent a unique subset of patients presenting to the emergency room. The acute presentation can be due to complications occurring in the tumor itself or visceral or vascular structures harboring the tumor. Multidetector computed tomography (MDCT) is the investigation of choice in the workup of these patients and enables appropriate and timely management. Management of the complication depends primarily on the extent of the underlying malignancy and the involvement of other viscera. The purpose of this article is to depict the imaging features of these complications on MDCT.

Effectiveness of MR enterography for the assessment of small-bowel diseases beyond Crohn disease

The use of cross-sectional imaging techniques for the noninvasive evaluation of small-bowel disorders is increasing. The effectiveness of magnetic resonance (MR) enterography for the evaluation of Crohn disease, in particular, is well described in the literature. In addition, MR enterography has an evolving though less well documented role to play in the evaluation of other small-bowel diseases, including various benign and malignant neoplasms arising in isolation or in polyposis syndromes such as Peutz-Jeghers, inflammatory conditions such as vasculitis and treatment-induced enteritis, infectious processes, celiac disease, diverticular disease, systemic sclerosis, and bowel duplication. MR enterography may be useful also for the evaluation of intermittent and low-grade small-bowel obstructions. Advantages of MR imaging over computed tomography (CT) for enterographic evaluations include superb contrast resolution, lack of associated exposure to ionizing radiation, ability to acquire multiplanar primary image datasets, ability to acquire sequential image series over a long acquisition time, multiphasic imaging capability, and use of intravenous contrast media with better safety profiles. MR enterography also allows dynamic evaluations of small-bowel peristalsis and distensibility of areas of luminal narrowing and intraluminal masses by repeating sequences at different intervals after administering an additional amount of the oral contrast medium. Limitations of MR enterography in comparison with CT include higher cost, less availability, more variable image quality, and lower spatial resolution. The advantages and disadvantages of MR enterography performed with ingestion of the oral contrast medium relative to MR enteroclysis performed with infusion of the oral contrast medium through a nasoenteric tube are less certain.

Ischemic bowel: uncommon imaging findings in a case of cocaine enteropathy

While the clinical findings of cocaine-induced enteropathy from mesenteric ischemia are fairly well understood, there is a paucity of imaging description and detail in the literature that describes these findings. Imaging characteristics of cocaine-induced mesenteric ischemia on CT examination include bowel edema, mucosal enhancement, venous engorgement, mesenteric free fluid, and dilatation of the small bowel lumen. A thorough history, physical examination, and laboratory testing are critical for the diagnosis and prompt surgical intervention may be necessary. We present a case of cocaine-induced mesenteric ischemia in a 49 year old male which resolved within 24 hours of supportive therapy.

Mesenteric vascular occlusion: comparison of ancillary CT findings between arterial and venous occlusions and independent CT findings suggesting life-threatening events

OBJECTIVE

To compare the ancillary CT findings between superior mesenteric artery thromboembolism (SMAT) and superior mesenteric vein thrombosis (SMVT), and to determine the independent CT findings of life-threatening mesenteric occlusion.

MATERIALS AND METHODS

Our study was approved by the institution review board. We included 43 patients (21 SMAT and 22 SMVT between 1999 and 2008) of their median age of 60.0 years, and retrospectively analyzed their CT scans. Medical records were reviewed for demographics, management, surgical pathology diagnosis, and outcome. We compared CT findings between SMAT and SMVT groups. Multivariate analysis was conducted to determine the independent CT findings of life-threatening mesenteric occlusion.

RESULTS

Of 43 patients, 24 had life-threatening mesenteric occlusion. Death related to mesenteric occlusion was 32.6%. A thick bowel wall (p < 0.001), mesenteric edema (p < 0.001), and ascites (p = 0.009) were more frequently associated with SMVT, whereas diminished bowel enhancement (p = 0.003) and paralytic ileus (p = 0.039) were more frequent in SMAT. Diminished bowel enhancement (OR = 20; p = 0.007) and paralytic ileus (OR = 16; p = 0.033) were independent findings suggesting life-threatening mesenteric occlusion.

CONCLUSION

The ancillary CT findings occur with different frequencies in SMAT and SMVT. However, the independent findings indicating life-threatening mesenteric occlusion are diminished bowel wall enhancement and paralytic ileus.

Acute bowel ischemia: analysis of diagnostic error by overlooked findings at MDCT angiography

To retrospectively evaluate the frequency and type of findings that were missed in the original reports of multi-detector CT angiography (MDCTA) in patients with suspected acute bowel ischemia. From January 2007 to March 2011, a series of 35 patients who underwent MDCTA of the abdomen and pelvis and had surgery were included. The reports of the initial CT were retrospectively compared with the discharge diagnosis and surgical reports. Discrepant or missing findings were re-evaluated and divided into relevant or not relevant regarding the diagnosis. In 23 of the 35 patients (66 %), all findings were correctly diagnosed in the initial MDCTA report. In the remaining 12 of the 35 patients (34 %), lesions that were not reported were present at surgery. In 10 of the 12 (83 %) patients, the overlooked findings were relevant and subtle: gas in the portal vein (n = 3), gas in the bowel wall (n = 3), gas in the portal vein and bowel wall (n = 2), thrombotic occlusion of the superior mesenteric artery (n = 1), and thrombotic occlusion of the inferior mesenteric artery (n = 1). In 2 of the 12 (17 %) patients in whom the MDCTA-overlooked findings were classified as non-relevant, bowel ischemia was found at surgery. With retrospective image interpretation, 83 % of the patients with occlusive mesenteric ischemia at surgery were correctly identified, whereas the remaining 17 % with non-occlusive mesenteric ischemia at surgery showed non-relevant findings at MDCTA. About 33 % of relevant findings of bowel ischemia were overlooked by the initial MDCTA interpretation, most were subtle findings. However, secondary reading revealed most of these findings and can serve to improve diagnostic performance.

Value of CT in the discrimination of fatal from non-fatal stercoral colitis

Objective

Clinical presentation and physical signs may be unreliable in the diagnosis of stercoral colitis (SC). This study evaluates the value of computed tomography (CT) in distinguishing fatal from non-fatal SC.

Materials and Methods

Ten patients diagnosed as SC were obtained from inter-specialist conferences. Additional 13 patients with suspected SC were identified via the Radiology Information System (RIS). These patients were divided into two groups; fatal and non-fatal SCs. Their CT images are reviewed by two board-certified radiologists blinded to the clinical data and radiographic reports.

Results

SC occurred in older patients and displayed no gender predisposition. There was significant correlation between fatal SC and CT findings of dense mucosa (p = 0.017), perfusion defects (p = 0.026), ascites (p = 0.023), or abnormal gas (p = 0.033). The sensitivity, specificity, and accuracy of dense mucosa were 71%, 86%, and 81%, respectively. These figures were 75%, 79%, and 77% for perfusion defects; 75%, 80%, and 78% for ascites; and 50%, 93%, and 78% for abnormal gas, respectively. Each CT sign of mucosal sloughing and pericolonic abscess displayed high specificity of 100% and 93% for diagnosing fatal SC, respectively. However, this did not reach statistical significance in diagnosing fatal SC.

Conclusion

CT appears to be valuable in discriminating fatal from non-fatal SC.

Multidetector computed tomography in large bowel lesions-a study of 100 cases

This study aims to evaluate the role of multidetector computed tomography (MDCT) in detecting and classifying the large bowel lesions. A prospective study of 100 adult patients was conducted from June 2007 to October 2009. Rectal and IV contrast were used for three dimensional reconstruction. Angiography was performed in cases of suspected ischemic pathology. CT colongraphy was done to evaluate adenomas. CT findings were correlated and confirmed by either colonoscopy, biopsy, postoperative findings or follow-up CT. The pathologies were common in 50-70 yrs (44%). M: F ratio was 2:1. Malignant lesions were seen in (55%) followed by inflammatory lesions in 26%, diverticulitis and ischemic colitis in 6% each. Miscellaneous conditions like polyps, volvulus and intussusceptions were seen in 7%. Adenocarcinoma was the common malignancy (81.2%). Present study showed that adenocarcinomas were associated with marked thickening of bowel wall (>1.5 cm) in 85.4% of patients, asymmetrical wall thickening (96.4%), focal involvement (length <10 cm) in 85.5% with heterogeneous post contrast enhancement (96.3%). Inflammatory lesions showed mild thickening (69%),segmental or diffuse involvement (77%), symmetrical wall thickening (89%) and homogenous post contrast enhancement (81%). Ischemic lesions showed marked thickening (83.4%), symmetrical thickening (100%) and homogenous enhancement (100%). Diverticulitis showed marked thickening (100%), asymmetrical wall thickening (66.7%) with heterogeneous post contrast enhancement (100%), with pericolic fluid. Arterial/venous thrombosis was diagnosed in 66.66%. Three per cent had benign adenomatous polyps on CT colonographic studies. MDCT was accurate in 98.2% cases for differentiating between benign and malignant etiology and is the modality of choice.

Radiologists' performance in the diagnosis of acute intestinal ischemia, using MDCT and specific CT findings, using a variety of CT protocols

The aim of this study was to evaluate the performance of radiologists in the diagnosis of acute intestinal ischemia using specific multi-detector CT findings. The abdominal CT scans of 90 patients were retrospectively reviewed by three radiologists: an abdominal imaging specialist, an experienced general radiologist, and a senior resident. Forty-seven patients had surgically proven intestinal ischemia and comprised the case group, while 43 patients had no evidence of intestinal ischemia at surgery and comprised the control group. Images were reviewed in a random and blinded fashion. Radiologists' performance in diagnosing bowel ischemia from other bowel pathologies was evaluated. The sensitivity, specificity, and accuracy for diagnosing bowel ischemia were 89%, 67%, and 79% for the abdominal imager; 83%, 67%, and 76% for the general radiologist; and 66%, 83%, and 74% for the senior resident, respectively. The calculated kappa value for inter-observer agreement regarding the presence of bowel ischemia was 0.79. CT findings that significantly distinguished bowel ischemia from other bowel pathologies were decreased or absent bowel wall enhancement, filling defect in the superior mesenteric artery, small bowel pneumatosis, and gas in the portal veins or superior mesenteric vein. For most of these signs, there was good inter-observer agreement. Radiologists' performance in diagnosing bowel ischemia is good, but lower than previously reported since a significant amount of cases are evaluated using a suboptimal CT technique. Radiologists' experience and expertise have an important impact on their performance.

Cytomegalovirus enterocolitis in apparently immunocompetent hosts: evaluation of the radiologic findings and clinical features

OBJECTIVE

To describe the clinical and radiologic features of cytomegalovirus (CMV) enterocolitis in apparently immunocompetent hosts.

MATERIALS AND METHODS

Our institutional review board approved this retrospective study, and informed consent was waived. Twelve apparently immunocompetent patients (7 women and 5 men; mean age, 58 years) with pathologically proven CMV enterocolitis were included. Computed tomographic (CT) scans were retrospectively reviewed to determine the extent and the location of mural thickening, maximal mural thickness, enhancement pattern, that is, single-halo, double-halo, and homogeneous patterns, and ascites.

RESULTS

Eight patients had comorbidities potentially affecting the host immune status, whereas 4 patients were apparently healthy before presentation. On CT, all patients showed mural thickening (range, 4-11 mm) involving the colon (n = 8), the small bowel (n = 1), or both (n = 3). Segmental involvement was most common (n = 9 for colon and n = 2 for small bowel), whereas focal involvement of the rectum (n = 1) and diffuse involvement of the entire ileum (n = 1) or the entire small bowel and colon (n = 1) were also noted. Colonic lesions showed variable enhancement patterns, including the single-halo (n = 6), homogeneous (n = 3), and double-halo patterns (n = 2), whereas all small-bowel lesions in 4 patients exhibited a single-ring pattern. Ascites was present in 7 patients. Complications requiring surgery occurred in 3 patients and included refractory bleeding (n = 2) and bowel perforation (n = 1).

CONCLUSIONS

Cytomegalovirus enterocolitis in immunocompetent hosts typically develops in elderly subjects with comorbidities, although it may also affect relatively young and healthy subjects. On CT, it is characterized by mild mural thickening of the small bowel and the colon and frequently shows segmental involvement and a single-halo enhancement pattern.

Acute and chronic mesenteric ischemia: MDCT findings

Mesenteric ischemia is caused by a reduction in mesenteric blood flow. It can be divided into acute and chronic, based upon the rapidity and the degree to which the blood flow is compromised. The authors retrospectively reviewed 22 cases of mesenteric ischemia, diagnosed by multidetector computed tomography (MDCT) in our service, and confirmed by surgery or clinical follow-up. The frequency of the diagnostic findings of chronic and acute mesenteric ischemia was evaluated. The improvement of three-dimensional (3D) MDCT allows accurate assessment of mesenteric vessels. Therefore, it demonstrates changes in ischemic bowel segments helpful in determining the primary cause of the disease, and can identify the complications in patients with acute and chronic mesenteric ischemia.

Spontaneous dissection of the superior mesenteric artery

We describe a case of spontaneous dissection and thrombosis of the superior mesenteric artery in a 54-year-old man who presented with new onset of hypertension and epigastric pain. Initial unsuccessful treatment with catheter-directed thrombolysis was followed by surgical intervention. In cases in which an extensive intimectomy is performed, early institution of antiplatelet therapy or anticoagulation may be necessary to preserve vessel patency due to the presence of a prothrombotic surface and compromised outflow.

Abdominal angina

Abdominal angina is an underrecognized cause of postprandial abdominal pain and weight loss. Diagnosis is often delayed and requires both a careful exclusion of more common causes and a high degree of clinical suspicion, based on the patient's age, the coexistence of multiple risk factors for atherosclerosis, and the presence of vasculopathy in other districts. Appropriate investigations include duplex ultrasound, traditional angiography, magnetic resonance angiography, computed tomography angiography, and tonometry. The purpose of this review is to discuss the pathophysiology and clinical presentation of chronic mesenteric ischemia and to suggest a diagnostic flowchart for this complex condition.

Nonoperative Management of Isolated Celiac and Superior Mesenteric Artery Dissection: Case Report and Review of the Literature

Isolated dissection of the origin of both celiac and superior mesenteric arteries is a rare vascular pathology with limited management guidelines. The presentation is generally nonspecific, most often manifesting with epigastric pain radiating to the back. A high diagnostic index of suspicion and stepwise management are essential for a successful outcome. This case report details the clinical course of a 57-year-male who presented with a 2-week history of epigastric discomfort with back pain and was found to have focal celiac artery dissection with aneurysmal dilation of 1.2 cm. His vital signs were stable, and the physical examination was unremarkable. At this time, he was placed on antiplatelet medication and was scheduled for endovascular repair of his celiac aneurysm with a covered stent graft. Two weeks later, recurrent abdominal pain prompted a repeat computed tomographic scan that revealed sequential superior mesenteric artery (SMA) dissection. The patient was admitted and anticoagulated. A complete workup ruled out underlying collagen vascular and autoimmune pathology. He remained stable, with significant symptomatic improvement. After 6 months, anticoagulation was discontinued and antiplatelet therapy was instituted for long-term management. Subsequent operative or endovascular intervention was not required. The patient was continuing to do well on his 18-month clinical follow-up. There are 71 cases of SMA and 12 cases of celiac artery dissection in the literature. This report outlines this rare presentation of isolated, proximal sequential celiac artery and SMA dissection. This case illustrates that conservative management may be warranted in uncomplicated, isolated visceral arterial dissection.

Spectrum of CT findings in patients with atrial fibrillation and nontraumatic acute abdomen

OBJECTIVE

The purpose of our study was to review the wide spectrum of pertinent CT findings in patients with acute nontraumatic abdominal pain in the setting of atrial fibrillation.

CONCLUSION

Underlying embolic or hemorrhagic complications are common in patients with acute nontraumatic abdominal pain in the setting of atrial fibrillation and can be accurately seen on CT.

CT diagnosis of acute mesenteric ischemia from various causes

OBJECTIVE

Acute mesenteric ischemia can be caused by various conditions such as arterial occlusion, venous occlusion, strangulating obstruction, and hypoperfusion associated with nonocclusive vascular disease, and the CT findings vary widely depending on the cause and underlying pathophysiology. The aim of this article is to review the CT appearances of acute mesenteric ischemia in various conditions.

CONCLUSION

Recognition of characteristic CT appearances and the variations associated with each cause may help in the accurate interpretation of CT in the diagnosis of mesenteric ischemia.

[Efficacy of rituximab combined with cyclophosphamide in a patient with systemic lupus erythematosus and peritoneal vasculitis refractory to conventional inmunosupressive therapy]

Peritoneal vasculitis is a rare and severe clinical manifestation of systemic lupus erythematosus. We report a patient who presented with ascites due to peritoneal vasculitis and cutaneous, articular, hematological and renal inflammatory activity. Treatment with glucocorticoids and immunosuppressive drugs was ineffective. In view of the resistance to different therapies, 4 weekly infusions of 375mg/m2 of rituximab (RTX) were started, in association with cyclophosphamide pulses during the first and the third weeks. With this treatment strategy, the patient reached a complete response which was achieved in later flares of inflammatory activity (the second and third flares were multisystemic and with ascites again, and the fourth flare with nephritis).

Imaging in intestinal ischemic disorders

Intestinal ischemia and infarction are a heterogeneous group of diseases that have as their unifying theme hypoxia of the small bowel or colon. The incidence of bowel ischemia and infarction is on the rise for several reasons: the aging of the population, the ability of intensive care units to salvage critically ill patients, and heightened clinical awareness of these disorders. Improvements in diagnostic imaging techniques have greatly contributed to the earlier diagnosis of intestinal ischemia, which can have a positive influence on patient outcomes. In this article, role of radiology in the detection, differential diagnosis, and management of patients who have intestinal ischemia and infarction is discussed.

Recurrent small bowel infarction in a young man: polycythaemia or vasculitis?

A 29-year-old man presented with a 3 day history of right lower quadrant pain, nausea and vomiting. There was tenderness in the right lower quadrant. At surgery the appendix was normal but an infarcted terminal ileum segment was found and resected. Histopathological examination was suggestive of vasculitis. The patient was discharged in good condition and follow-up for the first year was unremarkable. Unfortunately he developed another episode of bowel ischaemia in the second year and underwent resection of a short segment of proximal ileum. An autoimmune profile was negative. However, subsequent blood tests confirmed polycythaemia. Small bowel infarction due to polycythaemia in a young patient is rare and may be difficult to diagnose on clinical grounds.

Abdominal CT findings in small bowel perforation

Small bowel perforation is an emergent medical condition for which the diagnosis is usually not made clinically but by CT, a common imaging modality used for the diagnosis of acute abdomen. Direct CT features that suggest perforation include extraluminal air and oral contrast, which are often associated with secondary CT signs of bowel pathology. This pictorial review illustrates the CT findings of small bowel perforation caused by various clinical entities.