Multidetector CT angiography in the diagnosis of mesenteric ischemia

Role of multidetector CT angiography in the evaluation of suspected mesenteric ischemia

OBJECTIVE

To assess the role of multidetector CT angiography (MDCTA) in the diagnosis of acute mesenteric ischemia (AMI) and to compare the diagnostic utility of axial images with reconstructed images.

MATERIALS AND METHODS

In this Institute Review Board approved prospective study, MDCTA was performed on 31 patients who presented with the clinical suspicion of AMI (25M; 6F, age range: 16-73 years). Axial and reconstructed images of each patient were evaluated independently by two radiologists for evidence of bowel wall thickening, abnormal mucosal enhancement, bowel dilatation or obstruction, mesenteric stranding, ascites, solid organ infarcts, pneumatosis intestinalis or porto-mesenteric gas, and mesenteric arterial or venous occlusion. MDCT findings were correlated with the surgical findings and clinical outcome. Patients were later divided into two groups: a study group of patients with proven AMI and a control group of patients with an alternate diagnosis, for the purpose of statistical analysis.

RESULTS

AMI was correctly diagnosed in all 16 patients on MDCTA (100% sensitivity and specificity) of whom nine patients underwent surgical exploration. Three patients expired before surgery and the remaining 5 patients were proven based on positive clinical and laboratory findings. Mesenteric arterial occlusion was seen in 7 patients while 5 patients had portomesenteric venous thrombosis. Reconstructed images using minimum intensity projection, volume rendering and multiplanar volume reconstruction were found to perform better for the detection of vascular abnormalities and improved the diagnostic confidence of both radiologists in the evaluation of bowel and mesenteric abnormalities.

CONCLUSION

MDCTA is an effective non-invasive modality for the diagnosis of mesenteric ischemia.

Acute abdominal pain in the older adult

Abdominal pain in older adults is a concerning symptom common to a variety of diagnoses with high morbidity and mortality. Organizing the differential into categories based on pathology (inflammatory, obstructive, vascular, or other causes) provides a framework for the history, physical, and diagnostic studies. An organized approach and treatment and considerations specific to the geriatric population are discussed.

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.

Multidetector CT imaging in mesenteric ischemia--pearls and pitfalls

Mesenteric ischemia is a complex and devastating disease which still remains a diagnostic challenge to the clinicians due to non-specific clinical and laboratory findings. Several imaging features have been described with multidetector computed tomography which allows the diagnosis of mesenteric ischemia with high sensitivity and specificity. However, there are imaging features which overlap with other pathologies including benign inflammation and infection. Knowledge of imaging findings in mesenteric ischemia and its potential mimics is important in early and definitive diagnosis.

Chronic atherosclerotic mesenteric ischemia (CMI)

Chronic mesenteric ischemia (CMI) is most likely caused by atherosclerosis and less frequently by external compression and vasculitis. Symptomatic CMI is an uncommon, potentially under-diagnosed condition caused by fixed stenoses or occlusion of, in most conditions, at least two visceral arteries. If only one of the three major bowel-providing arteries — the celiac trunk, and the superior and inferior mesenteric arteries — is affected, the patient is usually asymptomatic due to a tight collateral network. The only exception is the celiac artery compression syndrome which represents primarily a compression syndrome of celiac plexus nerves by the arcuate ligament in conjunction with a compression of the celiac trunk. CMI of atherosclerotic origin is associated with a high morbidity and mortality. During the last decade, endovascular revascularization has replaced surgical revascularization as the therapy of choice in most centers. This article reviews the most relevant clinical aspects of the disease and the current practice of diagnosis and treatment of CMI.

Acute mesenteric ischemia: diagnostic approach and surgical treatment

Mortality related to acute mesenteric arterial occlusion remains very high. Patient survival is dependent on prompt recognition and revascularization before ischemia progresses to intestinal gangrene. Biphasic computed tomography angiography has surpassed angiography as the diagnostic test of choice due to its ability to define the arterial anatomy and to evaluate secondary signs of mesenteric ischemia. Unlike chronic mesenteric ischemia, the treatment of acute arterial mesenteric ischemia, either embolic or thrombotic, remains largely surgical. This is due to the emergent need for revascularization combined with a careful evaluation of the intestines. Endovascular techniques remain useful, however, and can save precious time in the treatment of these challenging patients if integrated into a treatment pathway combined with definitive surgical treatment. A new hybrid endovascular-surgical treatment for the treatment of acute mesenteric thrombosis is described.

[Radiological interventional procedures for the acute abdomen]

In patients with acute thrombo-embolic occlusion of the superior mesenteric artery, catheter-assisted thrombolytic therapy represents a procedure of increasing importance in addition to surgery and intensive care treatment. The thrombolytic drugs utilized for this purpose are urokinase, streptokinase and recombinant tissue plasminogen activator (rtPA).Therapeutic embolization is predominantly used in the treatment of arterial bleeding from the gastro-intestinal tract, the liver, the intestines (due to an aneurysm or vascular malformation) and in bleeding from intestinal anastomoses. Polyvinyl alcohol particles, embospheres, gelfoam and microcoils can be utilized as embolic agents. Percutaneous transhepatic cholangiodrainage and stent implantation are applied in patients with biliary obstructions caused by inoperable tumors of the gall bladder or bile ducts, of the pancreatic head or duodenum and by metastases located in the liver parenchyma or hepatic hilum.Image-guided percutaneous drainage is a valuable option in the management of abscesses in the peritoneal cavity; less common indications are lymphoceles, biliomas, urinomas, hematomas, necrosis and pseudocysts.

High-risk chief complaints III: abdomen and extremities

Abdominal and extremity complaints are a frequent reason for presentation to the emergency department. Although these are common complaints, several abdominal and extremity disease entities may be missed or may be subject to delayed diagnosis. This article provides an overview of the diagnosis and management of several high-risk abdominal and extremity complaints, including appendicitis, abdominal aortic aneurysm, mesenteric ischemia, bowel obstruction, retained foreign body, hand and finger lacerations, fractures, and compartment syndrome. Each section focuses primarily on the pitfalls in diagnosis by highlighting the limitations of history, physical examination findings, and diagnostic testing and provides specific risk management strategies.

64-Slice CT angiography of the abdominal aorta and abdominal arteries: comparison of the diagnostic efficacy of iobitridol 350 mgI/ml versus iomeprol 400 mgI/ml in a prospective, randomised, double-blind multi-centre trial

Purpose

The purpose of this study was to assess the influence of iodine concentration on diagnostic efficacy in multi-detector-row computed tomography (MDCT) angiography of the abdominal aorta and abdominal arteries.

Methods

IRB approval and informed consent were obtained. In this double-blind trial, patients were randomised to undergo MDCT angiography of the abdominal arteries during administration of iobitridol (350 mgI/ml) or iomeprol (400 mgI/ml). Each centre applied its own technique for delivery of contrast medium, regardless of iodine concentration. Diagnostic efficacy, image quality, visualisation of the arterial wall and arterial enhancement were evaluated. A total of 153 patients received iobitridol and 154 received iomeprol.

Results

The ability to reach a diagnosis was “satisfactory” to “totally satisfactory” in 152 (99.3%) and 153 (99.4%) patients respectively. Image quality was rated as being “good” to “excellent” in 94.7 and 94.8% segments respectively. Similar results were observed for image quality of arterial walls (84.3 vs. 83.2%). The mean relative changes in arterial enhancement between baseline and arterial phase images showed no statistically significant differences.

Conclusion

This study demonstrated the non-inferiority of the 350 versus 400 mgI/ml iodine concentration, in terms of diagnostic efficacy, in abdominal MDCT angiography. It also confirmed the high robustness and reliability of this technique across multi-national practices.

Intestinal ischemia in the elderly

Mesenteric ischemia in the elderly is an uncommon but often fatal disorder for which the prognosis depends entirely on the speed and accuracy of the diagnosis. A high index of suspicion is required as the early signs and symptoms, at a time when ischemic changes are reversible, are typically nonspecific or absent. This article reviews the clinical spectrum of mesenteric ischemia in the elderly with particular emphasis on the varied presentations, evaluation, and management of ischemic disorders of the intestines.

Prognostic value of multidetector computed tomography in bowel infarction

PURPOSE

This study aimed to correlate computed tomography (CT) findings and outcomes in patients affected by bowel infarction.

MATERIALS AND METHODS

Twenty-seven patients with bowel infarction due to vascular obstruction were evaluated with multidetector CT (MDCT) to establish the prognostic value of CT findings and their correlation with the origin of the ischaemia. The chi-square test was used to analyse the results (p</=0.05).

RESULTS

MDCT images allowed recognition of the nature of ischaemia in all cases. In particular, arterial occlusion was found in 67% of patients and venous obstruction in 33%. The overall mortality rate was 63%. Outcome closely correlated with the kind of vascular obstruction, with a mortality rate of 89% in arterial forms and 11% in venous forms. Bowel-wall hyperdensity (2/9 venous occlusions), loss of wall enhancement (1/9 venous occlusions, 2/18 arterial occlusions) and wall thickening (8/9 venous obstructions, 2/18 arterial occlusions) were predictive of good outcome. Bowel-loop dilatation (4/9 venous occlusions, 13/18 arterial occlusions), intramural pneumatosis (1/9 venous occlusions, 17/18 arterial occlusions), mesenteric venous gas (2/9 venous occlusions, 11/18 arterial occlusions), portal venous gas (1/9 venous occlusions, 4/18 arterial occlusions), pneumoperitoneum (8/18 arterial occlusions) and pneumoretroperitoneum (1/18 arterial occlusions) were predictive of poor outcome. Ascites (6/9 venous occlusions, 12/18 arterial occlusions) did not add any prognostic information.

CONCLUSIONS

MDCT is able to detect the nature of bowel ischaemia and provide important prognostic information.

MR angiography with parallel acquisition for assessment of the visceral arteries: comparison with conventional MR angiography and 64-detector-row computed tomography

The purpose of the study was to retrospectively compare three-dimensional gadolinium-enhanced magnetic resonance angiography (conventional MRA) with MRA accelerated by a parallel acquisition technique (fast MRA) for the assessment of visceral arteries, using 64-detector-row computed tomography angiography (MDCTA) as the reference standard. Eighteen patients underwent fast MRA (imaging time 17 s), conventional MRA (29 s) and MDCTA of the abdomen and pelvis. Two independent readers assessed subjective image quality and the presence of arterial stenosis. Data were analysed on per-patient and per-segment bases. Fast MRA yielded better subjective image quality in all segments compared with conventional MRA (P = 0.012 for reader 1, P = 0.055 for reader 2) because of fewer motion-induced artefacts. Sensitivity and specificity of fast MRA for the detection of arterial stenosis were 100% for both readers. Sensitivity of conventional MRA was 89% for both readers, and specificity was 100% (reader 1) and 99% (reader 2). Differences in sensitivity between the two types of MRA were not significant for either reader. Interobserver agreement for the detection of arterial stenosis was excellent for fast (kappa = 1.00) and good for conventional MRA (kappa = 0.76). Thus, subjective image quality of visceral arteries remains good on fast MRA compared with conventional MRA, and the two techniques do not differ substantially in the grading of arterial stenosis, despite the markedly reduced acquisition time of fast MRA.

Acute mesenteric ischaemia: facts and perspectives

Acute mesenteric ischaemia is a catastrophic abdominal emergency with an extremely high mortality rate. This article discusses the aetiology, diagnosis and treatment of acute mesenteric ischaemia with emphasis on avoidance of common errors that contribute to the poor outcome inherent to this condition.

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.

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.

Diagnosis and management of splanchnic ischemia

Splanchnic or gastrointestinal ischemia is rare and randomized studies are absent. This review focuses on new developments in clinical presentation, diagnostic approaches, and treatments. Splanchnic ischemia can be caused by occlusions of arteries or veins and by physiological vasoconstriction during low-flow states. The prevalence of significant splanchnic arterial stenoses is high, but it remains mostly asymptomatic due to abundant collateral circulation. This is known as chronic splanchnic disease (CSD). Chronic splanchnic syndrome (CSS) occurs when ischemic symptoms develop. Ischemic symptoms are characterized by postprandial pain, fear of eating and weight loss. CSS is diagnosed by a test for actual ischemia. Recently, gastro-intestinal tonometry has been validated as a diagnostic test to detect splanchnic ischemia and to guide treatment. In single-vessel CSD, the complication rate is very low, but some patients have ischemic complaints, and can be treated successfully. In multi-vessel stenoses, the complication rate is considerable, while most have CSS and treatment should be strongly considered. CT and MR-based angiographic reconstruction techniques have emerged as alternatives for digital subtraction angiography for imaging of splanchnic vessels. Duplex ultrasound is still the first choice for screening purposes. The strengths and weaknesses of each modality will be discussed. CSS may be treated by minimally invasive endoscopic treatment of the celiac axis compression syndrome, endovascular antegrade stenting, or laparotomy-assisted retrograde endovascular recanalization and stenting. The treatment plan is highly individualized and is mainly based on precise vessel anatomy, body weight, co-morbidity and severity of ischemia.

Epidemiology, risk and prognostic factors in mesenteric venous thrombosis

BACKGROUND

Epidemiological reports on risk and prognostic factors in patients with mesenteric venous thrombosis (MVT) are scarce.

METHODS

Patients with MVT were identified through the inpatient and autopsy registry between 2000 and 2006 at Malmö University Hospital.

RESULTS

Fifty-one patients had MVT, diagnosed at autopsy in six. The highest incidence (11.3 per 100,000 person-years) was in the age category 70-79 years. Activated protein C resistance was present in 13 of 29 patients tested. D-dimer at admission was raised in all five patients tested. Multidetector row computed tomography (CT) in the portal venous phase was diagnostic in all 20 patients investigated, of whom 19 were managed conservatively. The median length of resected bowel in 12 patients who had surgery was 0.6 (range 0.1-2.2) m. The overall 30-day mortality rate was 20 percent; intestinal infarction (P = 0.046), treatment on a non-surgical ward (P = 0.001) and CT not done (P = 0.022) were associated with increased mortality. Cancer was independently associated with long-term mortality: hazard ratio 4.03, 95 percent confidence interval 1.03 to 15.85; P = 0.046.

CONCLUSION

Portal venous phase CT appeared sensitive in diagnosing MVT. As activated protein C resistance was a strong risk factor, lifelong anticoagulation should be considered.