Acute gastrointestinal bleeding: value of MDCT

Computed tomography versus lower endoscopy as initial diagnostic method for evaluating patients with hematochezia at emergency room

For acute lower gastrointestinal bleeding (LGIB), lower gastrointestinal endoscopy is the preferred initial diagnostic test. However, it is difficult to perform urgently. Computed tomography (CT) is a convenient alternative.This study aimed to determine the diagnostic performance of CT compared to lower endoscopy as an initial test for evaluating acute LGIB.The medical records of 382 patients who visited our emergency department with hematochezia between January 2012 and January 2017 were retrospectively analyzed. Of them, 112 underwent CT, 65 underwent colonoscopy, and 205 underwent sigmoidoscopy as an initial test. For each method, sensitivity, specificity, positive predictive value, and negative predictive value were calculated upon active bleeding site detection and LGIB etiology diagnosis.The sensitivity, specificity, positive predictive value, and negative predictive value of CT for active bleeding site detection were 85.7%, 100%, 100%, and 96.9%, respectively, while those for identifying the etiology of LGIB were 87.4%, 40.0%, 83.5, and 47.6%, respectively.CT was not inferior to lower endoscopy for active bleeding site detection. Early localization and the exclusion of active bleeding were possible with CT. Etiology was diagnosed with high sensitivity and PPV by CT. Thus, CT can be an alternative initial diagnostic tool for evaluating acute LGIB.

ACR Appropriateness Criteria® Nonvariceal Upper Gastrointestinal Bleeding

Upper gastrointestinal bleeding (UGIB) remains a significant cause of morbidity and mortality with mortality rates as high as 14%. This document addresses the indications for imaging UGIB that is nonvariceal and unrelated to portal hypertension. The four variants are derived with respect to upper endoscopy. For the first three, it is presumed that upper endoscopy has been performed, with three potential initial outcomes: endoscopy reveals arterial bleeding source, endoscopy confirms UGIB without a clear source, and negative endoscopy. The fourth variant, "postsurgical and traumatic causes of UGIB; endoscopy contraindicated" is considered separately because upper endoscopy is not performed. When endoscopy identifies the presence and location of bleeding but bleeding cannot be controlled endoscopically, catheter-based arteriography with treatment is an appropriate next study. CT angiography (CTA) is comparable with angiography as a diagnostic next step. If endoscopy demonstrates a bleed but the endoscopist cannot identify the bleeding source, angiography or CTA can be typically performed and both are considered appropriate. In the event of an obscure UGIB, angiography and CTA have been shown to be equivalent in identifying the bleeding source; CT enterography may be an alternative to CTA to find an intermittent bleeding source. In the postoperative or traumatic setting when endoscopy is contraindicated, primary angiography, CTA, and CT with intravenous contrast are considered appropriate. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Is urgent CT angiography necessary in cases of acute lower gastrointestinal bleeding?

Acute lower gastrointestinal bleeding usually presents as hematochezia, rectal bleeding or melena and represents 1-2% of the medical appointments in the Emergency Services. Mortality reaches the 30-40% and it is highly related with the severity and associated comorbidity. Most clinical practice guidelines include colonoscopy at some point in the diagnostic and therapeutic process (urgent for severe cases and ambulatory for mild ones) and look for predictors of severity. In the last years, there have been numerous studies where is clear the relevance and complementarity of advanced diagnostic imaging techniques, gradually incorporated as an alternative or second step in severe cases. Therefore, we have made a review of current scientific evidence to establish a clinical prediction rule for optimal indication of CT angiography in these patients. However, future studies providing greater robustness and level of evidence are necessary.

Computed tomography angiography in patients with active gastrointestinal bleeding

Gastrointestinal bleeding represents a common medical emergency, with considerable morbidity and mortality rates, and a prompt diagnosis is essential for a better prognosis. In such a context, endoscopy is the main diagnostic tool; however, in cases where the gastrointestinal hemorrhage is massive, the exact bleeding site might go undetected. In addition, a trained professional is not always present to perform the procedure. In an emergency setting, optical colonoscopy presents limitations connected with the absence of bowel preparation, so most of the small bowel cannot be assessed. Scintigraphy cannot accurately demonstrate the anatomic location of the bleeding and is not available at emergency settings. The use of capsule endoscopy is inappropriate in the acute setting, particularly in the emergency department at night, and is a highly expensive method. Digital angiography, despite its high sensitivity, is invasive, presents catheterization-related risks, in addition to its low availability at emergency settings. On the other hand, computed tomography angiography is fast, widely available and minimally invasive, emerging as a promising method in the diagnostic algorithm of these patients, being capable of determining the location and cause of bleeding with high accuracy. Based on a critical literature review and on their own experience, the authors propose a computed tomography angiography protocol to assess the patient with gastrointestinal bleeding.

Gastrointestinal Bleeding Scintigraphy in the Early 21st Century

Gastrointestinal bleeding scintigraphy performed with (99m)Tc-labeled autologous erythrocytes or historically with (99m)Tc-sulfur colloid has been a clinically useful tool since the 1970s. This article reviews the history of the techniques, the different methods of radiolabeling erythrocytes, the procedure, useful indications, diagnostic accuracy, the use of SPECT/CT and CT angiography to evaluate gastrointestinal bleeding, and Meckel diverticulum imaging. The causes of pediatric bleeding are discussed by age.

Cross-sectional imaging of common and unusual complications after endoscopic retrograde cholangiopancreatography

Endoscopic retrograde cholangiopancreatography (ERCP) is currently a primarily therapeutic procedure that is extensively employed to treat several biliopancreatic disorders. Although widely considered a safe procedure, ERCP is associated with a non-negligible morbidity and occasional mortality. Due to the number and complexity of operative ERCPs performed, radiologists are increasingly faced with urgent requests for investigation of suspected post-procedural complications, which often have similar clinical and laboratory manifestations. This pictorial essay reviews the usual post-procedural CT findings, the clinical features and imaging appearances of common and unusual post-ERCP occurrences including interstitial oedematous and necrotising acute pancreatitis, haemorrhages, retroperitoneal and intraperitoneal duodenal perforations, infections and stent-related complications. Emphasis is placed on the pivotal role of multidetector CT, which is warranted after complex or prolonged ERCP procedures as it represents the most effective modality to detect and grade ERCP-related complications and to monitor nonsurgically treated patients. Timely diagnosis and optimal management require a combination of clinical and laboratory data with imaging appearances; therefore, this article aims to provide an increased familiarity with interpretation of early post-ERCP studies, particularly to triage those occurrences that require interventional or surgical treatment. In selected patients MRI allows imaging pancreatitis and abnormal collections without the use of ionising radiation.

Teaching Points

• Endoscopic retrograde cholangiopancreatography (ERCP) allows treating many biliopancreatic disorders.

• Due to the number and complexity of procedures, post-ERCP complications are increasingly encountered.

• Main complications include acute pancreatitis, haemorrhages, duodenal perforation and infections.

• Diagnosis and management of complications rely on combined clinical, laboratory and imaging data.

• Multidetector CT is most effective to diagnose, categorise and monitor post-ERCP complications.

Hemorrhagic complications of anticoagulant therapy: role of multidetector computed tomography and spectrum of imaging findings from head to toe

Highly effective in preventing and treating thromboembolic conditions in acute and chronic settings, anticoagulant therapy is associated with a non-negligible risk of hemorrhagic complications with a considerable clinical impact. Advanced age and comorbidities further increase the risk of bleeding during heparinization, treatment with low-molecular-weight heparins or long-term oral warfarin anticoagulation. Multidetector computed tomography represents the mainstay diagnostic technique to image-suspected hemorrhages in anticoagulated patients, as it can quickly assess presence, site, and extent of hemorrhage, identify active bleeding, and possible underlying diseases. Cross-sectional imaging appearances of the wide spectrum of anticoagulant therapy-related bleeding complications are hereby presented, including peripheral and thoracic-abdominal wall muscular hematomas, intrathoracic, abdominal, retroperitoneal genitourinary, gastrointestinal, and brain hemorrhages. Prompt recognition and comprehensive diagnostic assessment with multidetector computed tomography allow clinicians to correctly choose treatment modification or withdrawal, surgery, or interventional procedures as needed, with the aim to reduce the associated morbidity and mortality.

Accuracy of CT angiography in the diagnosis of acute gastrointestinal bleeding: systematic review and meta-analysis

OBJECTIVE

To assess the diagnostic accuracy of computed tomography (CT) angiography in the evaluation of patients with an episode of acute gastrointestinal haemorrhage.

METHODS

Systematic review and meta-analysis to estimate pooled accuracy indices. A bivariate random effects model was adjusted to obtain a summary receiver-operating characteristic (sROC) curve and the corresponding area under the curve (AUC).

RESULTS

Twenty-two studies were included and provided data on 672 patients (range of age 5-74) with a mean age of 65 years. The overall sensitivity of CT angiography for detecting active acute GI haemorrhage was 85.2 % (95 % CI 75.5 % to 91.5 %). The overall specificity of CT angiography was 92.1 % (95 % CI 76.7 % to 97.7 %). The likelihood ratios for positive and negative test results were 10.8 (95 % CI 3.4 to 34.4) and 0.16 (95 % CI 0.1 to 0.27) respectively, with an AUC of 0.935 (95 % CI 0.693 to 0.989). The sources of heterogeneity explored had no significant impact on diagnostic performance.

CONCLUSIONS

CT shows high diagnostic accuracy and is an excellent diagnostic tool for detection and localising of intestinal bleeding sites. It is highly available, provides fast detection and localisation of the bleeding site, and is minimally invasive.

KEY POINTS

• CT angiography is increasingly used for investigating severe gastrointestinal bleeding. • This systematic review and meta-analysis updates previous ones. • In patients with massive gastrointestinal bleeding, CT angiography/MDCT detects bleeding accurately. • CT angiography is useful in locating the bleeding site and determining appropriate treatment.

Extensive colonic necrosis following cardiac arrest and successful cardiopulmonary resuscitation: report of a case and literature review

Non-occlusive colonic ischaemia is a recognized albeit rare entity related to low blood flow within the visceral circulation and in most reported cases the right colon was affected. This is the second case report in the literature of extensive colonic necrosis following cardiac arrest and cardiopulmonary resuscitation (CPR). A 83-year-old Caucasian woman was admitted to our hospital due to a low energy hip fracture. On her way to the radiology department she sustained a cardiac arrest. CPR started immediately and was successful. A few hours later, the patient developed increasing abdominal distension and severe metabolic acidocis. An abdominal multidetector computed tomography (MDCT) scan was suggestive of intestinal ischaemia. At laparotomy, the terminal ileum was ischaemic and extensive colonic necrosis was found, sparing only the proximal third of the transverse colon. The rectum was also spared. The terminal ileum and the entire colon were resected and an end ileostomy was fashioned. Although the patient exhibited a transient improvement during the immediate postoperative period, she eventually died 24h later from multiple organ failure. Histology showed transmural colonic necrosis with no evidence of a thromboembolic process or vasculitis. Therefore, this entity was attributed to a low flow state within the intestinal circulation secondary to the cardiac arrest.

In the workup of patients with obscure gastrointestinal bleed, does 64-slice MDCT have a role?

Purpose:

The purpose was to prospectively determine the sensitivity of 64-slice MDCT in detecting and diagnosing the cause of obscure gastrointestinal bleed (OGIB).

Materials and Methods:

Our study included 50 patients (male 30, female 20) in the age range of 3–82 years (average age: 58.52 years) who were referred to our radiology department as part of their workup for clinically evident gastrointestinal (GI) bleed or as part of workup for anemia (with and without positive fecal occult blood test). All patients underwent conventional upper endoscopy and colonoscopy before undergoing CT scan. Following a noncontrast scan, all patients underwent triple-phase contrast CT scan using a 64-slice CT scan system. The diagnostic performance of 64-slice MDCT was compared to the results of capsule endoscopy, 99m-technetium-labeled red blood cell scintigraphy (99mTc-RBC scintigraphy), digital subtraction angiography, and surgery whenever available.

Results:

CT scan showed positive findings in 32 of 50 patients. The sensitivity, specificity, positive predictive value, and negative predictive values of MDCT for detection of bleed were 72.2%, 42.8%, 81.2%, and 44.4%, respectively. Capsule endoscopy was done in 15 patients and was positive in 10 patients; it had a sensitivity of 71.4%. Eleven patients had undergone 99mTc-RBC scintigraphy prior to CT scan, and the result was positive in seven patients (sensitivity 70%). Digital subtraction angiography was performed in only eight patients and among them all except one patient showed findings consistent with the lesions detected on MDCT.

Conclusion:

MDCT is a sensitive and noninvasive tool that allows rapid detection and localization of OGIB. It can be used as the first-line investigation in patients with negative endoscopy and colonoscopy studies. MDCT and capsule endoscopy have complementary roles in the evaluation of OGIB.

Obscure and occult gastrointestinal bleeding: comparison of different imaging modalities

Patients with persistent, recurrent, or intermittent bleeding from the gastrointestinal (GI) tract for which no definite cause has been identified by initial esophagogastroduodenoscopy, colonoscopy, or conventional radiologic evaluation are considered to have an obscure GI bleeding (OGIB). The diagnosis and management of patients with OGIB is challenging, often requiring extensive and expensive workups. The main objective is the identification of the etiology and site of bleeding, which should be as rapidly accomplished as possible, in order to establish the most appropriate therapy. The introduction of capsule endoscopy and double balloon enteroscopy and the recent improvements in CT and MRI techniques have revolutionized the approach to patients with OGIB, allowing the visualization of the entire GI tract, particularly the small bowel, until now considered as the "dark continent" . In this article we review and compare the radiologic and endoscopic examinations currently used in occult and OGIB, focusing on diagnostic patterns, pitfalls, strengths, weaknesses, and value in patients' management.

Advances in small bowel imaging

The small intestine has been difficult to examine by traditional endoscopic and radiologic techniques. Within the past 10 years, advances have led to an explosion of technologies that facilitate examination of the entire small intestine. Wireless video capsule endoscopy, deep enteroscopy using balloon-assisted or spiral techniques, computer tomography (CT) and magnetic resonance (MR) enterography have facilitated the diagnosis, monitoring, and management of patients with small intestinal diseases. These technologies are complementary, each with its advantages and limitations. Capsule endoscopy provides a detailed view of the mucosal surface and has excellent patient acceptance, but does not allow therapeutics. Deep enteroscopy allows careful inspection of the mucosa and therapeutics, but is time consuming and invasive. Enterography (CT or MR) allows examination of the small bowel wall and surrounding structures. The initial best test for detecting small intestinal disease depends on clinical presentation and an astute differential diagnosis.

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.

[Gastrointestinal bleeding: the role of radiology]

Gastrointestinal bleeding represents a diagnostic challenge both in its acute presentation, which requires the point of bleeding to be located quickly, and in its chronic presentation, which requires repeated examinations to determine its etiology. Although the diagnosis and treatment of gastrointestinal bleeding is based on endoscopic examinations, radiological studies like computed tomography (CT) angiography for acute bleeding or CT enterography for chronic bleeding are becoming more and more common in clinical practice, even though they have not yet been included in the clinical guidelines for gastrointestinal bleeding. CT can replace angiography as the diagnostic test of choice in acute massive gastrointestinal bleeding, and CT can complement the endoscopic capsule and scintigraphy in chronic or recurrent bleeding suspected to originate in the small bowel. Angiography is currently used to complement endoscopy for the treatment of gastrointestinal bleeding.

Arterial interventions in gastrointestinal bleeding

The diagnosis and management of gastrointestinal (GI) bleeding are complicated. A multitude of pathologic processes results in GI bleeding, and often, the bleeding is intermittent in nature. Of the available diagnostic tools, angiography has been the gold standard. Management of patients requires a multidisciplinary approach involving gastroenterologists, interventional radiologists, and surgeons. Therapeutic arterial interventions include pharmacologic control with the use of intraarterial vasopressin, embolization with temporary and permanent embolizing materials, and catheter-induced vasospasm.

Diagnosis of acute gastrointestinal bleeding: comparison of the arterial, the portal, and the combined set using 64-section computed tomography

OBJECTIVES

To compare the respective capabilities of the arterial, the portal, and the combined set in the detection and localization of acute gastrointestinal (GI) bleeding with 64-section computed tomography (CT).

METHODS

A total of 46 patients with acute GI bleeding and who had undergone both 64-section CT and digital subtraction angiography were included in this study. The results of angiography were used as a reference standard. Two radiologists independently reviewed the 3 sets of CT images (arterial set, the unenhanced and arterial-phase images; portal set, the unenhanced and portal venous-phase images; combined set, the unenhanced and arterial-phase and portal venous-phase images). The diagnostic accuracy was assessed by a receiver operating characteristic analysis.

RESULTS

For each observer, the Az values were 0.915 and 0.931 for the arterial set, 0.903 and 0.933 for the portal set, and 0.919 and 0.911 for the combined set, respectively. The differences were not statistically significant among the 3 data sets for each observer (P > 0.05). Both observers correctly detected the bleeding site in 81.3% and 84.4% on the arterial set, in 81.3% and 84.4% on the portal set, and in 84.4% and 84.4% on the combined set, respectively.

CONCLUSIONS

Using 64-section CT, the diagnostic performance was not different among the arterial, the portal, and the combined set for the detection and localization of acute GI bleeding.

Small intestinal vascular malformation bleeding: diagnosis by double-balloon enteroscopy combined with abdominal contrast-enhanced CT examination

Aim

The purpose of this study was to explore the value of double-balloon enteroscopy combined with abdominal vascular-enhanced CT examination for the diagnosis of intestinal vascular malformation bleeding, to explore a simple and effective method for the diagnosis of small intestinal vascular malformation bleeding.

Methods

Ten patients with intestinal bleeding were first examined with double-balloon enteroscopy. If active bleeding considered as vascular malformation was observed, the patient underwent abdominal vascular-enhanced CT examination. If no active bleeding was observed with double-balloon enteroscopy, the patient also underwent abdominal vascular-enhanced CT examination. When intestinal vascular malformation bleeding was diagnosed with double-balloon enteroscopy and/or abdominal vascular-enhanced CT examination, the patient underwent surgical operation and vascular malformation was confirmed with pathologic diagnosis.

Results

In ten patients who underwent double-balloon enteroscopy examination, active intestinal bleeding was observed in seven patients and no active bleeding was observed in three patients. All ten patients underwent abdominal vascular-enhanced CT examination and vascular malformation was detected in all the patients with confirmation by pathologic diagnosis.

Conclusion

Double-balloon enteroscopy combined with abdominal vascular enhanced CT examination is a simple and effective method for the diagnosis of intestinal vascular malformation bleeding.

The value of multidetector-row computed tomography for localization of obscure acute gastrointestinal bleeding

PURPOSE

There are no simple guidelines on when to perform multidetector-row computed tomography (MDCT) for diagnosis of obscure acute gastrointestinal bleeding (AGIB). We used a risk scoring system to evaluate the diagnostic power of MDCT for patients with obscure AGIB.

MATERIALS AND METHODS

Ninety-two patients with obscure AGIB who were referred for an MDCT scan after unsuccessful endoscopic treatment at presentation were studied. We recorded clinical data and calculated Blatchford score for each patient. Patients who required transfusion more than 500mL of blood to maintain the vital signs were classified as high-risk patients. Two radiologists independently reviewed and categorized MDCT signs of obscure AGIB. Discordant findings were resolved by consensus. One-way ANOVA was used to compare clinical data between two groups; kappa statistics were used to estimate agreement on MDCT findings between radiologists.

RESULTS

Of the 92 patients, 62 (67.4%) were classified as high-risk patients. Blatchford scores of high-risk patients were significantly greater than those of low-risk patients. Sensitivity for MDCT diagnosing obscure AGIB was 81% in high-risk patients, as compared with 50% in the low-risk. When used in conjunction with selection of the cut-off value of 13 in Blatchford scoring system, the sensitivity and specificity of MDCT were 70.9% and 73.7%, respectively. Contrast extravasation was the most specific sign of AGIB (k=.87), recognition of which would have improved diagnostic accuracy.

CONCLUSIONS

With the aid of Blatchford scoring system for evaluating the disease severity, MDCT can localize the bleeders of obscure AGIB more efficiently.

The role of colonoscopy and radiological procedures in the management of acute lower intestinal bleeding

There are multiple strategies for evaluating and treating lower intestinal bleeding (LIB). Colonoscopy has become the preferred initial test for most patients with LIB because of its diagnostic and therapeutic capabilities and its safety. However, few studies have directly compared colonoscopy with other techniques and there are controversies regarding the optimal timing of colonoscopy, the importance of colon preparation, the prevalence of stigmata of hemorrhage, and the efficacy of endoscopic hemostasis. Angiography, radionuclide scintigraphy, and multidetector computed tomography scanning are complementary modalities, but the requirement of active bleeding at the time of the examination limits their routine use. In addition, angiography can result in serious complications. This review summarizes the available evidence regarding colonoscopy and radiographic studies in the management of acute LIB.

Prospective study comparing multi-detector row CT and endoscopy in acute gastrointestinal bleeding

BACKGROUND

Upper and lower acute gastrointestinal bleeding (AGIB) is associated with high rates of mortality and morbidity. The latest computerized tomography (CT) imaging techniques play an important role in the treatment of this pathology.

METHODS

Twenty-nine patients with severe AGIB (11 upper, 18 lower), all hemodynamically stable, underwent endoscopy followed by a multi-detector row CT (MDCT) scan. Endoscopic and MDCT accuracy for the anatomical localization and etiology of AGIB was assessed, the diagnosis being considered correct when the two procedures were concordant or when the diagnosis was confirmed by angiographic, surgical, or post-mortem findings.

RESULTS

The sensitivity in identifying the site and etiology of bleeding was, respectively, 100% and 90.9% for the MDCT scan, compared with 72.7% and 54.5% for endoscopy in upper AGIB, and 100% and 88.2% for the MDCT scan, compared with 52.9% and 52.9% for endoscopy, in lower AGIB.

CONCLUSIONS

Considering the advantages of MDCT over endoscopy, we propose a new diagnostic algorithm for AGIB.

Preliminary estimate of triphasic CT enterography performance in hemodynamically stable patients with suspected gastrointestinal bleeding

OBJECTIVE

The objective of our study was to retrospectively evaluate the performance of triphasic CT enterography and identify causes of false-negative CT results in hemodynamically stable patients with suspected gastrointestinal bleeding.

MATERIALS AND METHODS

A retrospective review of 48 patients (male-female ratio, 22:26) with suspected gastrointestinal bleeding (first-episode gastrointestinal bleed, n = 19; obscure gastrointestinal bleed, n = 29) who underwent triphasic CT enterography was performed. All patients had endoscopic, pathologic, or other imaging confirmation within 3 months of triphasic CT enterography. The sensitivity and specificity of triphasic CT enterography were calculated using pathology, endoscopy, or other imaging confirmation as the reference standard. Results were retrospectively reviewed to determine the cause of missed findings at triphasic CT enterography.

RESULTS

The overall sensitivity and specificity of triphasic CT enterography for detecting gastrointestinal bleeding was 33% (7/21) and 89% (24/27), respectively. Sensitivity and specificity were higher in first-episode gastrointestinal bleed cases (42% and 100%, respectively) than in obscure gastrointestinal bleed cases (22% and 85%). In the subset of patients undergoing capsule endoscopy (n = 17), only triphasic CT enterography identified two of three bleeding sources. Triphasic CT enterography did not identify six ulcers, four vascular malformations, two hemorrhoids, a duodenal mass, and a bleeding colonic diverticulum. The missed findings at triphasic CT enterography were attributed to being CT occult (n = 9), perception errors (n = 4), and technical errors (n = 1). If perception errors are excluded, the sensitivity of triphasic CT enterography increases to 52% (11/21).

CONCLUSION

Triphasic CT enterography can be a useful and complementary test in the evaluation of clinically stable patients with suspected gastrointestinal bleeding by identifying the bleeding source in one third to one half of patients. Because of the potential for perception errors, radiologists should familiarize themselves with the appearance of bleeding sources at CT enterography.

Optimized multidetector computed tomographic protocol for the diagnosis of active obscure gastrointestinal bleeding: a feasibility study

OBJECTIVE

The purpose of this feasibility study was to prospectively evaluate an optimized multidetector computed tomographic protocol for the diagnosis of active obscure gastrointestinal bleeding (OGIB).

METHODS

Between October 2006 and February 2008, patients admitted for active OGIB were included in this prospective unicenter study. Water was administered orally and rectally as neutral luminal contrast material. A contrast-enhanced 16-row multidetector computed tomography (MDCT) was performed in the arterial and venous phases. Mesenteric digital subtraction angiography was carried out immediately after MDCT as standard of reference.

RESULTS

Six patients were included in this study. Multidetector computed tomography identified the bleeding site and source in 5 (83%) of the patients. Digital subtraction angiography was performed in 4 patients, and the result was positive in 1 (25%) of the patients. Multidetector computed tomography detected the site and source of bleeding in 2 patients whose digital subtraction angiographic result was negative.

CONCLUSIONS

The results of this feasibility study indicate that optimized MDCT is an excellent diagnostic tool for the diagnosis of active OGIB.

Multi-detector row CT of patients with acute intestinal bleeding: a new perspective using multiplanar and MIP reformations from submillimeter isotropic voxels

Acute intestinal bleeding is a severe condition, with a mortality rate of up to 40% in case of associated hemodynamic instability. The diagnosis of acute intestinal bleeding is often challenging and to date, there is no definite consensus upon the most appropriate technique for this specific diagnosis. This pictorial essay illustrates our preliminary use of multiplanar (MPR) and maximum intensity projection (MIP) reformations using MDCT scanner with submillimeter and isotropic voxels as an adjunct to axial images in patients with acute intestinal bleeding. MDCT examinations were routinely performed with 64-slice helical CT scanner and images were reconstructed 0.6-mm thickness at 0.5-mm intervals. Multiplanar reconstructions and MIP views were created with a commercially available workstation. Reformatted images from submillimeter isotropic voxels enhanced the depiction of subtle vascular abnormalities and served as a useful adjunct to the axial plane images to improve diagnostic capabilities. Although we are aware that reformatted images should not replace careful analysis of the axial images in patients with acute gastrointestinal bleeding, reformatted images from submillimeter isotropic voxels may clarify the cause of the bleeding, add confidence to image analysis and help interventional radiologists or surgeons improving planning approach.