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.

Multidetector CT angiography in acute gastrointestinal bleeding: why, when, and how.

Acute gastrointestinal (GI) bleeding remains an important cause of emergency hospital admissions, with substantial related morbidity and mortality. Bleeding may relate to the upper or lower GI tract, with the dividing anatomic landmark between these two regions being the ligament of Treitz. The widespread availability of endoscopic equipment has had an important effect on the rapid identification and treatment of the bleeding source. However, the choice of upper or lower GI endoscopy is largely dictated by the clinical presentation, which in many cases proves misleading. Furthermore, there remains a large group of patients with negative endoscopic results or failed endoscopy, in whom additional techniques are required to identify the source of GI bleeding. Multidetector computed tomography (CT) with its speed, resolution, multiplanar techniques, and angiographic capabilities allows excellent visualization of both the small and large bowel. Multiphasic multidetector CT allows direct demonstration of bleeding into the bowel and is helpful in the acute setting for visualization of the bleeding source and its characterization. Thus, multidetector CT angiography provides a time-efficient method for directing and planning therapy for patients with acute GI bleeding. The additional information provided by multidetector CT angiography before attempts at therapeutic angiographic procedures leads to faster selective catheterization of bleeding vessels, thereby facilitating embolization. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.313105206/-/DC1.

CT findings of misleading features of colonic diverticulitis.

Colonic diverticulitis (CD) is a common entity whose diagnosis is particularly based on computed tomography (CT) examination, which is the imaging technique of choice. However, unusual CT findings of CD may lead to several difficulties and potential pitfalls: due to technical errors in the management of the CT examination, due to the anatomical situation of the diseased colon, in diagnosing unusual complications that may concern the gastrointestinal tract, intra- and retroperitoneal viscera or the abdominal wall, and in differentiating CD from other abdominal inflammatory and infectious conditions or colonic cancer. The aim of this work is to delineate the pitfalls of CT imaging and illustrate misleading CT features in patients with suspected CD.

Accuracy of multidetector computed tomography in differentiating primary epiploic appendagitis from left acute colonic diverticulitis associated with secondary epiploic appendagitis.

The objectives of this study are to evaluate the prevalence of left acute colonic diverticulitis (LACD) associated with secondary epiploic appendagitis (SEA) detected by computed tomography (CT); to describe CT features that distinguish LACD associated with SEA from primary epiploic appendagitis (PEA); and to assess the accuracy of CT in diagnosing LACD associated with SEA versus PEA. Institutional review board approval was obtained. We retrospectively identified 46 consecutive patients with LACD between July 2004 and July 2005 and 26 patients with PEA between 2000 and 2005 investigated using multidetector CT. Two radiologists blinded to the final diagnosis reviewed the CT images for findings of LACD-associated SEA or PEA. Each reader classified each CT scan into one of four categories: PEA, LACD-associated SEA, LACD without SEA, and indeterminate. Fisher's exact test and Wilcoxon test were performed to compare the groups. The prevalence of LACD-associated SEA was 71% (33/46) in the LACD group. The accuracy of CT was 100% for diagnosing LACD-associated SEA (33/33), 100% for diagnosing LACD without SEA (13/13), and 96% for diagnosing PEA (25/26). Colon wall thickening, "inflamed diverticulum", extraluminal gas, abscess or phlegmon, multiple paracolic fatty lesions, and a thin hyperattenuated rim were significantly associated with LACD-associated SEA. Neither the dot sign nor parietal peritoneal thickening showed good accuracy for differentiating PEA from LACD-associated SEA. CT is accurate for distinguishing LACD-associated SEA from PEA. The findings that perform best for diagnosing SEA are evidence of diverticulitis, multiple fatty lesions, and a thin hyperattenuated rim.

Location of the transition zone in CT of small-bowel obstruction: added value of multiplanar reformations.

PURPOSE: To assess the additional value of multiplanar reformations (MPR) in comparison with axial images alone for location of the transition zone in CT of mechanical small-bowel obstruction (SBO). MATERIALS AND METHODS: Sixty-nine consecutive patients with mechanical SBO underwent 16-slice multi detector row CT (MDCT). The gold standard for the precise location of the transition zone was established by two experienced abdominal radiologists, unblinded to clinical and surgical reports, reviewing all CT examinations. On a workstation, two blinded readers independently located the transition zone using first axial slices alone and then 1 month later MPR (axial, coronal, sagittal and oblique views) according to a three-point confidence scale. Diagnostic accuracy and mean confidence score were evaluated for both the transverse and multiplanar data sets. RESULTS: Accuracy of transition zone location for reader 1 and reader 2 was 86% and 84% with axial slices alone, and by using MPR 93% (significant: P = 0.03) and 90% (not significant: P = 0.08), respectively. Mean confidence score was significantly increased for both readers using MPR: 0.3 higher (P = 0.0001) and 0.37 higher (P = 0.0001) respectively. CONCLUSION: MPR can increase both accuracy and confidence in the location of the transition zone in CT of SBO.

Cerebral venous thrombosis and multidetector CT angiography: tips and tricks.

Because of the great diversity of clinical features, its unforeseeable evolution, and a small proportion of cases that will worsen in the acute phase, cerebral venous thrombosis must be diagnosed as early as possible so that specific treatment can be started, typically transcatheter thrombolysis or systemic anticoagulation. Unenhanced computed tomography (CT) is usually the first imaging study performed on an emergency basis. Unenhanced CT allows detection of ischemic changes related to venous insufficiency and sometimes demonstrates a hyperattenuating thrombosed dural sinus or vein. Helical multidetector CT venography with bolus power injection of contrast material and combined use of two-dimensional and three-dimensional reformations (maximum intensity projection, integral display, and volume rendering) provides exquisite anatomic detail of the deep and superficial intracranial venous system and can demonstrate filling defects. However, common variants of the sinovenous system should not be mistaken for sinus thrombosis. A comprehensive diagnostic approach facilitates imaging of cerebral venous thrombosis with multidetector CT.