CT of small bowel ischemia

Association Between Bowel Wall Thickening and Long-Term Outcomes in Decompensated Liver Cirrhosis

INTRODUCTION

Bowel wall thickening is commonly observed in liver cirrhosis, but few studies have explored its impact on the long-term outcomes of patients with cirrhosis.

METHODS

Overall, 118 patients with decompensated cirrhosis were retrospectively enrolled, in whom maximum wall thickness of small bowel, ascending colon, transverse colon, descending colon, sigmoid colon, and rectum could be measured in computed tomography (CT) images. X-tile software was employed to determine the best cut-off values of each segment of bowel wall thickness for predicting the risk of further decompensation and death. Cumulative rates of further decompensation and death were calculated by Nelson-Aalen cumulative risk curve analyses. Predictors of further decompensation and death were evaluated by competing risk analyses. Sub-distribution hazard ratios (sHRs) were calculated.

RESULTS

Cumulative rates of further decompensation were significantly higher in patients with wall thickness of ascending colon ≥ 11.7 mm (P = 0.014), transverse colon ≥ 3.2 mm (P = 0.043), descending colon ≥ 9.8 mm (P = 0.035), and rectum ≥ 7.2 mm (P = 0.045), but not those with wall thickness of small bowel ≥ 8.5 mm (P = 0.312) or sigmoid colon ≥ 7.1 mm (P = 0.237). Wall thickness of ascending colon ≥ 11.7 mm (sHR = 1.70, P = 0.030), transverse colon ≥ 3.2 mm (sHR = 2.15, P = 0.038), and rectum ≥ 7.2 mm (sHR = 2.38, P = 0.045) were independent predictors of further decompensation, but not wall thickness of small bowel ≥ 8.5 mm (sHR = 1.19, P = 0.490), descending colon ≥ 9.8 mm (sHR = 1.53, P = 0.093) or sigmoid colon ≥ 7.1 mm (sHR = 0.63, P = 0.076). Small bowel, ascending colon, transverse colon, descending colon, sigmoid colon, and rectum wall thickness were not significantly associated with death.

CONCLUSIONS

Colorectal wall thickening, but not small bowel wall, may be considered for the prediction of further decompensation in cirrhosis.

Identification of near-infrared characteristic bands of small bowel necrosis based on cellwise detection algorithm

The near-infrared spectroscopy is often used to distinguish small bowel necrosis due to necrotizing enterocolitis (NEC). The characteristic bands of small bowel necrosis, as an important basis for evaluating the confidence of the differentiation results, are challenging to identify quickly. In this study, we proposed to identify characteristic bands of lesion samples based on hyperspectral imaging (HSI) and cellwise outlier detection. Rabbits were used as an animal model to simulate the clinical symptoms of NEC. The rabbits were detected at intervals of 10, 30, 60, and 90 min. The characteristic bands were identified within the same rabbit, between different rabbits and at different times. The result showed the bands near 763 nm, corresponding to the absorption peak of deoxyhemoglobin, were the characteristic bands separating samples with NEC. The identification result was plausible because hypoxia was the main cause of NEC. The method was easy to perform.

Diagnostic potential of plasma biomarkers and exhaled volatile organic compounds in predicting the different stages of acute mesenteric ischaemia: protocol for a multicentre prospective observational study (TACTIC study)

INTRODUCTION

Acute mesenteric ischaemia (AMI) is a life-threatening condition with short-term mortality of up to 80%. The diagnosis of AMI has remained troublesome due to the non-specific clinical presentation, symptoms and laboratory findings. Early unambiguous diagnosis of AMI is critical to prevent progression from reversible to irreversible transmural intestinal damage, thereby decreasing morbidity and improving survival. The present study aims to validate a panel of plasma biomarkers and investigate volatile organic compound (VOC) profiles in exhaled air as a tool to timely and accurately diagnose AMI.

METHODS AND ANALYSIS

In this international multicentre prospective observational study, 120 patients (>18 years of age) will be recruited with clinical suspicion of AMI. Clinical suspicion is based on: (1) clinical manifestation, (2) physical examination, (3) laboratory measurements and (4) the physician's consideration to perform a CT scan. The patient's characteristics, repetitive blood samples and exhaled air will be prospectively collected. Plasma levels of mucosal damage markers intestinal fatty acid-binding protein and villin-1, as well as transmural damage marker smooth muscle protein 22-alpha, will be assessed by ELISA. Analysis of VOCs in exhaled air will be performed by gas chromatography time-of-flight mass spectrometry. Diagnosis of AMI will be based on CT, endovascular and surgical reports, clinical findings, and (if applicable) verified by histopathological examination.

ETHICS AND DISSEMINATION

The study protocol was approved by the Medical Research Ethics Committee (METC) of Maastricht University Medical Centre+ and Maastricht University (METC azM/UM), the Netherlands (METC19-010) and the Ethics Committee Research UZ/KU Leuven, Belgium (S63500). Executive boards and local METCs of other Dutch participating centres Gelre Ziekenhuizen (Apeldoorn), Medisch Spectrum Twente (Enschede), and University Medical Centre Groningen have granted permission to carry out this study. Study results will be disseminated via open-access peer-reviewed scientific journals and national/international conferences.

TRIAL REGISTRATION NUMBER

NCT05194527.

The Role of Imaging in Portal Vein Thrombosis: From the Diagnosis to the Interventional Radiological Management

PURPOSE

To illustrate diagnostic and interventional imaging for the characterization and treatment of portal vein thrombosis (PVT).

INTRODUCTION

The broad spectrum of congenital and acquired PVT manifestations is illustrated, with a focus on the pediatric population; diagnostic and interventional imaging techniques are described.

DESCRIPTION

PVT frequently presents as an incidental finding at imaging in the screening for liver diseases or for other unrelated reasons. PVT can be classified based on: extension (intrahepatic, extrahepatic, involving the spleno-mesenteric tract, etc.); degree (partial or complete); onset (acute or chronic); and with or without cavernomatous transformation. This comprehensive review relies on the experience gained from a large series of congenital and acquired PVT in a referral center for pediatric and adult liver transplantation. Diagnostic and interventional imaging techniques are described, including: color-Doppler and contrast-enhanced Ultrasound; CT and MR angiography; retrograde portography; percutaneous transhepatic, transplenic, and transmesenteric portography; transjugular intrahepatic portosystemic shunt creation. Pre- and post-operative imaging assessment of the surgical meso-rex bypass is discussed. The description is enriched with an original series of pictorial imaging findings.

CONCLUSION

PVT is a clinical condition associated with significant morbidity and mortality. Diagnostic and interventional imaging plays a crucial role in both conservative and operative management.

Mesenteric ischemia: a radiologic perspective

Mesenteric ischemia is a broad term encompassing several clinical conditions leading to impaired vascularity of bowel loops. Absence of specific clinical presentation and a definitive laboratory marker often lead to delayed diagnosis with high morbidity and mortality in the acute setting. Imaging plays a crucial role in the diagnosis and management. Multi-detector CT (MDCT) is the first line imaging modality for the evaluation of patients with suspected mesenteric ischemia and plays an important role for assessing its severity and complications. This review article highlights the causes, pathophysiology, imaging features and possible endovascular treatment options of mesenteric ischemia.

Comprehensive review of acute small bowel ischemia: CT imaging findings, pearls, and pitfalls

Acute small bowel ischemia is a life-threatening condition with a high mortality rate due to its lack of specific symptoms and laboratory profile, which render difficulty in establishing early diagnosis. The etiology of acute small bowel ischemia includes occlusive forms (arterial embolism, arterial thrombosis, and venous thrombosis) and nonocclusive mesenteric ischemia, of which arterial causes are far more common than venous causes. CT, the mainstay of accurate diagnoses, allows the identification of the features of vascular abnormalities and intestinal ischemic injuries, and helps clinicians to restore intestinal blood flow. Without treatment, the prognosis for acute small bowel ischemia is poor. A high index of suspicion and familiarity with the CT spectral findings of bowel ischemia are required to ensure rapid recognition of this condition.

CT manifestations of small bowel ischemia due to impaired venous drainage-with a correlation of pathologic findings

Acute abdominal pain may result from a wide variety of medical and surgical diseases. One of these diseases is small bowel ischemia, which may result in a catastrophic outcome if not recognized and treated promptly. Computed tomography (CT) by its faster image acquisition, thinner collimation, high resolution, and multiplanar reformatted images has become the most important imaging modality in evaluating the acute abdominal conditions. In this article, the author presents a description of the histology of the small bowel, pathophysiology of small bowel change, and a correlation of the pathologic and CT findings of the small bowel injuries due to impaired venous drainage. A convincing correlation of the microscopic mucosal condition with the enhancement pattern of the thickened small bowel wall on CT is useful in definitely describing the mucosal viability.

Imaging spectrum of abdominal manifestations of COVID-19

Coronavirus disease 2019 (COVID-19) has posed a serious threat to global public health with its rapid spread, high fatality, and severe burden on health care providers all over the world. Although COVID-19 has been established as a respiratory tract infection, it can manifest with gastrointestinal symptoms as a consequence of direct infection by the virus or due to inflammation-mediated cytotoxicity. It has been observed that COVID-19 patients presenting with gastrointestinal symptoms tend to progress to a severe form of disease with increased morbidity and mortality, thus indicating the need for timely management. COVID-19 manifests with a wide spectrum of radiologic findings on gastrointestinal tract imaging, encompassing bowel abnormalities, hepato-biliary and pancreatic involvement, vascular occlusion, and solid organ infarction. Early recognition of these imaging features can facilitate timely treatment of COVID-19 associated gastrointestinal tract complications and may prompt the diagnosis of COVID-19 in patients with atypical disease manifestations. The aim of this article is to provide an overview of the various gastrointestinal imaging manifestations that can be encountered in patients with COVID-19, with an emphasis on early diagnosis of the disease as well as treatment related complications.

Many faces of acute bowel ischemia: overview of radiologic staging

Acute bowel ischemia (ABI) can be life threatening with high mortality rate. In spite of the advances made in diagnosis and treatment of ABI, no significant change has occurred in the mortality over the past decade. ABI is potentially reversible with prompt diagnosis. The radiologist plays a central role in the initial diagnosis and preventing progression to irreversible intestinal ischemic injury or bowel necrosis. The most single imaging findings described in the literature are either non-specific or only present in the late stages of ABI, urging the use of a constellation of features to reach a more confident diagnosis. While ABI has been traditionally categorized based on the etiology with a wide spectrum of imaging findings overlapped with each other, the final decision for patient’s management is usually made on the stage of the ABI with respect to the underlying pathophysiology. In this review, we first discuss the pathologic stages of ischemia and then summarize the various imaging signs and causes of ABI. We also emphasize on the correlation of imaging findings and pathological staging of the disease. Finally, a management approach is proposed using combined clinical and radiological findings to determine whether the patient may benefit from surgery or not.

Cerebral and Splanchnic Vein Thrombosis: Advances, Challenges, and Unanswered Questions

Cerebral vein thrombosis (CVT) and splanchnic vein thrombosis (SVT) are two manifestations of venous thromboembolism (VTE) at unusual sites. They have an incidence at least 25-50 times lower than usual site VTE, but represent true clinical challenges. Recent evidence on the epidemiology, risk factors, prognosis, and treatment of CVT and SVT has been published in the last two decades, thus contributing to a better understanding of these diseases. The improvement in imaging techniques and a higher degree of clinical suspicion may have led to the observed increased frequency, whereas a better knowledge of provoking mechanisms could have contributed to reducing the proportion of events classified as unprovoked or idiopathic (13%-21% of CVT, 15%-27% of SVT). Few small randomized clinical trials and a number of observational studies, although hampered by heterogeneous therapeutic approaches, shed light on the safety and effectiveness of anticoagulant therapy in these populations. However, there are still some grey areas that warrant future research. In this narrative review, we discuss recent advances and therapeutic challenges in CVT and SVT.

Splanchnic Vein Thrombosis: Current Perspectives

Splanchnic vein thrombosis (SVT) including portal, mesenteric, splenic vein thrombosis and the Budd-Chiari syndrome, is a manifestation of unusual site venous thromboembolism. SVT presents with a lower incidence than deep vein thrombosis of the lower limbs and pulmonary embolism, with portal vein thrombosis and Budd-Chiari syndrome being respectively the most and the least common presentations of SVT. SVT is classified as provoked if secondary to a local or systemic risk factor, or unprovoked if the causative trigger cannot be identified. Diagnostic evaluation is often affected by the lack of specificity of clinical manifestations: the presence of one or more risk factors in a patient with a high clinical suspicion may suggest the execution of diagnostic tests. Doppler ultrasonography represents the first line diagnostic tool because of its accuracy and wide availability. Further investigations, such as computed tomography and magnetic resonance angiography, should be executed in case of suspected thrombosis of the mesenteric veins, suspicion of SVT-related complications, or to complete information after Doppler ultrasonography. Once SVT diagnosis is established, a careful patient evaluation should be performed in order to assess the risks and benefits of the anticoagulant therapy and to drive the optimal treatment intensity. Due to the low quality and large heterogeneity of published data, guidance documents and expert opinion could direct therapeutic decision, suggesting which patients to treat, which anticoagulant to use and the duration of treatment.

Acute mesenteric ischaemia: a pictorial review

Abstract

Acute mesenteric ischaemia (AMI) is an uncommon cause of acute hospital admission with high mortality rates (50–90%) that requires early diagnosis and treatment. With the increase in average life expectancy, AMI represents one of the most threatening abdominal conditions in elderly patients. Untreated, AMI will cause mesenteric infarction, intestinal necrosis, an overwhelming inflammatory response and death. Early intervention can reverse this process leading to a full recovery, but the diagnosis of AMI is difficult. The failure to recognise AMI before intestinal necrosis has developed is responsible for the high mortality of the disease. Unfortunately, common CT findings in bowel ischaemia are not specific. Therefore, it is often a combination of nonspecific clinical, laboratory and radiological findings that helps most in the correct interpretation of CT findings. The purpose of this article is to provide an overview of the anatomy, physiology of mesenteric perfusion and discussions of causes, pathogenesis and CT findings in various types of acute bowel ischaemia. Familiarity with various imaging features of mesenteric injury is essential to make a timely diagnosis that will lead to improved patient outcomes.

Teaching Points

• AMI is a potentially life-threatening disorder whose prognosis depends on early recognition, accurate diagnosis and timely intervention.

• Arterial inflow occlusion due to thrombosis or embolisation is the most common cause of AMI.

• Four aetiological types of AMI have been associated with different characteristics and risk factors (EAMI, TAMI, VAMI and NOMI).

• Physical examination and laboratory findings are not sensitive or specific for diagnosing AMI; therefore, MDCT is still the first-line imaging method in suspected AMI.

• Although a number of scoring systems for prognosis have been proposed, these have not been validated in large-scale studies.

Clinical manifestations and imaging tools in the diagnosis of splanchnic and cerebral vein thromboses

Splanchnic vein thrombosis (SVT) and cerebral vein thrombosis (CVT) are uncommon manifestation of venous thromboembolism (VTE), occurring less frequently than deep vein thrombosis of the lower extremities and pulmonary embolism. SVT encompasses portal vein thrombosis, mesenteric vein thrombosis, splenic vein thrombosis and the Budd-Chiari syndrome. It is therefore a heterogeneous disease, with differences in clinical manifestations according to the site of thrombosis. CVT includes thrombosis of the cortical or deep cerebral veins and thrombosis of the major dural venous sinuses. Clinical presentation is variable, with a wide spectrum of signs and symptoms that can mimic other cerebral diseases. There are no clinical algorithms or specific laboratory tests that can guide in the identification of SVT and CVT; therefore, the diagnosis relies exclusively on imaging tests. Conventional angiography once was the gold standard for the diagnosis of SVT and CVT, but it is rarely used nowadays. Abdominal ultrasound (US), computed tomography (CT) and magnetic resonance (MR) with angiography are currently used for the diagnosis of SVT; while cerebral CT and MR with angiography are currently used for the diagnosis of CVT. These imaging tests have different sensitivities/specificities and different advantages/disadvantages that should be kept into consideration when choosing the appropriate imaging test based on the suspected site of thrombosis. This narrative review summarizes the clinical and diagnostic approach to SVT and CVT.

Incidence and clinical presentation of portal vein thrombosis in cirrhotic patients

BACKGROUND

Portal vein thrombosis (PVT) is due to many risk factors, but its pathogenesis is still not clearly understood. To identify the risk factors for PVT, we analyzed the clinical characteristics and complications associated with PVT in cirrhotic patients.

METHODS

We studied patients with liver cirrhosis who were admitted to our unit from April 2009 to December 2014. The patients were divided into the PVT and non-PVT groups, and were compared by variables including gender, age, the etiology of cirrhosis, stage of cirrhosis, complications, imaging, and treatment.

RESULTS

PVT was found in 45 (9.8%) of 461 cirrhotic patients admitted to our hospital. Most patients (45.9%) had hepatitis B virus (HBV)-related cirrhosis, with a similar distribution of etiologies between the groups. However, there was no positive relationship between PVT and etiologies of cirrhosis. Most patients (71.5%) were in the stage of hepatic decompensation. No statistically significant differences were found in complications including esophageal varices, ascites, and hepatic encephalopathy between the groups. However, there was a significant positive correlation between hepatocellular carcinoma (HCC) and PVT (P<0.01). In 30 patients with PVT, thrombosis occurred in the portal vein and/or portal branches, 37.8% were diagnosed on ultrasound.

CONCLUSIONS

The incidence of PVT was 9.8%, mainly in patients with HBV-related cirrhosis. The development of PVT was associated with the severity of liver disease and HCC.

Radiological Evaluation of Bowel Ischemia

Intestinal ischemia, which refers to insufficient blood flow to the bowel, is a potentially catastrophic entity that may require emergent intervention or surgery in the acute setting. Although the clinical signs and symptoms of intestinal ischemia are nonspecific, computed tomography (CT) findings can be highly suggestive in the correct clinical setting. In our article, we review the CT diagnosis of arterial, venous, and nonocclusive intestinal ischemia. We discuss the vascular anatomy, pathophysiology of intestinal ischemia, CT techniques for optimal imaging, key and ancillary radiological findings, and differential diagnosis.

Detecting acute mesenteric ischemia in CT of the acute abdomen is dependent on clinical suspicion: Review of 95 consecutive patients

OBJECTIVES

(1) To evaluate the ability of emergency room radiologists to detect acute mesenteric ischemia (AMI) from computed tomography (CT) images in patients with acute abdominal pain. (2) To identify factors affecting radiologists' performance in the CT interpretation and patient outcome.

MATERIALS AND METHODS

A retrospective study of 95 consecutive patients treated for 97 AMI events between 2009 and 2013 was carried out. The etiology of AMI was embolism in 24 (25%), atherosclerotic vascular disease (ASVD) in 39 (40%), non-obstructive mesenteric ischemia (NOMI) in 25 (26%), and mesenteric venous thrombosis (MVT) in nine (9%) cases. The protocols, referrals and initial radiology reports of the abdominal CTs were analyzed. The CT studies were further scrutinized for vascular and intestinal findings.

RESULTS

The referring clinician had suspected AMI in 30 (31%) cases prior to imaging. The crucial findings of AMI had been stated in 97% of the radiology reports if the clinician had mentioned AMI suspicion in the referral; if not, the corresponding rate was 81% (p=0.04). Patients without suspicion of AMI prior to CT were more prone to undergo bowel resection. CT protocol was optimal for AMI (with contrast enhancement in arterial and venous phases) in only 34 (35%) cases. Intestinal findings were more difficult to detect than vascular findings. Vascular findings were retrospectively detectable in 92% of cases with embolism and 100% in ASVD and MVT. Some evidence of intestinal abnormality was retrospectively found in the CT findings in 92%, 100%, 100% and 67% of cases with embolism, ASVD, NOMI and MVT, respectively.

CONCLUSIONS

AMI is underdiagnosed in the CT of the acute abdomen if there is no clinical suspicion.

Common Postmortem Computed Tomography Findings Following Atraumatic Death: Differentiation between Normal Postmortem Changes and Pathologic Lesions

Computed tomography (CT) is widely used in postmortem investigations as an adjunct to the traditional autopsy in forensic medicine. To date, several studies have described postmortem CT findings as being caused by normal postmortem changes. However, on interpretation, postmortem CT findings that are seemingly due to normal postmortem changes initially, may not have been mere postmortem artifacts. In this pictorial essay, we describe the common postmortem CT findings in cases of atraumatic in-hospital death and describe the diagnostic pitfalls of normal postmortem changes that can mimic real pathologic lesions.

Review article: portal vein obstruction--epidemiology, pathogenesis, natural history, prognosis and treatment

BACKGROUND

Portal vein obstruction may be due to portal vein thrombosis (PVT) or its sequale, the portal cavernoma. PVT is a common complication in liver cirrhosis, however, it may also occur as a primary vascular disorder, in absence of any liver disease.

AIM

To review the current knowledge on nomenclature, etiology, pathophysiology, clinical presentation, diagnostic workup and management of adult patients with obstruction in the portal vein, either as a primary vascular disease in adults, or as a complication of liver cirrhosis.

METHODS

A structured search in PubMed was performed using defined keywords (portal vein obstruction, extra-hepatic portal vein obstruction, PVT and portal cavernoma), including full text articles and abstracts in English language.

RESULTS

Several causes, operating both at local and systemic level, might play an important role in the pathogenesis of PVT. Frequently, more than one risk factor could be identified; however, occasionally no single factor is discernible. Diagnosis of portal vein obstruction depends on clinical presentation, imaging and laboratory investigations. Prompt treatment greatly affects the patient's outcome.

CONCLUSIONS

Portal vein obstruction occurring either due to thrombosis in the portal vein or due to the portal cavernoma, can contribute to significant morbidity and mortality in patients with or without cirrhosis. In recent years our understanding of etio-pathogenesis of portal vein obstruction has evolved tremendously, which has led to significant improvement in treatment outcomes. There are still areas where more studies are needed to better clarify the management issues of portal vein obstruction.

How I treat splanchnic vein thrombosis

Antithrombotic treatment of splanchnic vein thrombosis (SVT) is a clinical challenge. Depending on the site of thrombosis, patients are at risk of developing liver insufficiency, portal hypertension, or bowel infarction and may experience recurrence in both the splanchnic veins and other vein segments. To prevent recurrence, anticoagulant therapy should be started as soon as possible after diagnosis and is often continued for an indefinite period of time. However, active bleeding is not infrequent at the time of SVT diagnosis, and major risk factors for bleeding, such as esophageal varices or a low platelet count, are frequently present in these patients. In real-world clinical practice, a proportion of SVT patients are left untreated because the risks associated with anticoagulant therapy are felt to exceed its benefits. However, the majority of patients receive anticoagulant drugs, with heterogeneous timing of initiation, drug choice, and dosages. Evidence to drive treatment decisions is limited because no randomized controlled trials have been carried out in these patients. This review provides practical guidance for the use of anticoagulant drugs in patients presenting with SVT, including symptomatic as well as incidentally detected events.

Portal vein thrombosis in liver cirrhosis

Portal vein thrombosis (PVT) is considered to be a frequent complication of liver cirrhosis. However, unlike PVT in patients without cirrhosis, very few data are available on the natural history and management of PVT in cirrhosis, despite its association with potentially life-threatening conditions, such as gastroesophageal bleeding and acute intestinal ischemia. Moreover, no consensus regarding PVT in cirrhosis exists. Suggested causes of PVT in cirrhosis include reduced portal blood flow velocity, multiple congenital or acquired thrombophilic factors, inherited or acquired conditions, and derangement of liver architecture. However, the understanding of PVT in cirrhosis is incomplete. In addition, information on the management of PVT in cirrhosis is inadequate. The aims of this review are to: (1) assemble data on the physiopathological mechanism, clinical findings, diagnosis and management of PVT in cirrhosis; (2) describe the principal factors most frequently involved in PVT development; and (3) summarize the recent knowledge concerning diagnostic and therapeutic procedures.

Acute Mesenteric Ischaemia-An Indian Perspective

In Western countries, acute mesenteric ischaemia is commonly due to arterial occlusion and occurs in patients who are usually in their seventh decade. A venous cause for intestinal gangrene has been reported in only about 10 %. We examined whether this was so in India and compared the clinical features of patients with mesenteric arterial and venous ischaemia and relate these to their ultimate prognosis. We studied retrospectively, the records of all patients admitted or referred to the department with a diagnosis of acute mesenteric ischaemia between January 1997 and October 2012, noting their demographic details and mode of presentation, the results of preoperative imaging and blood investigations, the extent of bowel ischaemia, and the length of bowel that was resected at operation and their outcome. There were 117 patients, 85 males and 32 females whose median age was 53 years. Mesenteric venous thrombosis was seen in 56 patients (48 %) and mesenteric arterial occlusion in 61 (52 %). Forty six patients died (39 %); 15 with venous occlusion (27 %) and 31 with arterial occlusion (51 %). Compared to patients with arterial occlusion, the patients with venous obstruction were younger, had a longer duration of symptoms, were less frequently hypotensive at presentation, had higher platelet counts, had a shorter length of bowel resected, had fewer colonic resections and had a lower mortality. Other predictors of mortality on multivariate analysis were a longer duration of symptoms, lower serum albumin and higher creatinine levels at presentation and a shorter length of residual bowel. In India, acute mesenteric ischaemia in tertiary care centres is due to venous thrombosis in almost half of the patients who are at least a decade younger than those in the West. Significant predictors of mortality include low serum albumin and raised creatinine levels, a shorter residual bowel length and an arterial cause for mesenteric ischaemia.

Mesenteric ischemia: the importance of differential diagnosis for the surgeon

Background

Intestinal ischemia is an abdominal emergency that accounts for approximately 2% of gastrointestinal illnesses. It represents a complex of diseases caused by impaired blood perfusion to the small and/or large bowel including acute arterial mesenteric ischemia (AAMI), acute venous mesenteric ischemia (AVMI), non occlusive mesenteric ischemia (NOMI), ischemia/reperfusion injury (I/R), ischemic colitis (IC). In this study different study methods (US, CT) will be correlated in the detection of mesenteric ischemia imaging findings due to various etiologies.

Methods

Basing on our institutions experience, 163 cases of mesenteric ischemia/infarction from various cases, investigated with CT and undergone surgical treatment were retrospectively evaluated, in particular trought the following findings: presence/absence of arterial/venous obstruction, bowel wall thickness and enhancement, presence/absence of spastic reflex ileus, hypotonic reflex ileus or paralitic ileus, mural and/or portal/mesenteric pneumatosis, abdominal free fluid, parenchymal ischemia/infarction (liver, kidney, spleen).

Results

To make an early diagnosis useful to ensure a correct therapeutic approach, it is very important to differentiate between occlusive (arterial, venous) and non occlusive causes (NOMI). The typical findings of each forms of mesenteric ischemia are explained in the text.

Conclusion

The radiological findings of mesenteric ischemia have different course in case of different etiology. In venous etiology the progression of damage results faster than arterial even if the symptomatology is less acute; bowel wall thickening is an early finding and easy to detect, simplifying the diagnosis. In arterial etiology the damage progression is slower than in venous ischemia, bowel wall thinning is typical but difficult to recognize so diagnosis may be hard. In the NOMI before/without reperfusion the ischemic damage is similar to AAMI with additional involvement of large bowel parenchymatous organs. In reperfusion after NOMI and after AAMI the CT and surgical findings are similar to those of AVMI, and the injured bowel results quite easy to identify. The prompt recognition of each condition is essential to ensure a successful treatment.

Early detection of acute mesenteric ischemia using diffusion-weighted 3.0-T magnetic resonance imaging in a porcine model

PURPOSE

The aim of this study was to investigate if 3.0-T diffusion-weighted magnetic resonance imaging (MRI) can be used for early detection of acute occlusive and nonocclusive mesenteric ischemia.

MATERIALS AND METHODS

In this study, approved by the official committee on animal affairs, proximal (occlusive) mesenteric ischemia and peripheral (nonocclusive) mesenteric ischemia were induced in 8 and 2, respectively, female domestic pigs. Proximal mesenteric ischemia was induced by intra-arterial injection of n-butyl-cyanoacrylate in the superior mesenteric artery or 1 of its main branches; peripheral mesenteric ischemia was induced by intra-arterial injection of microparticles. Before embolization and at 30-, 60-, and 90-minute intervals after embolization, diffusion-weighted imaging was performed, and apparent diffusion coefficient (ADC) maps were calculated on a clinical 3.0-T system. Immediately after the last MRI session, animals were killed to provide a pathological correlation for mesenteric ischemia.

RESULTS

Ischemic bowel parts appeared hyperintense on diffusion-weighted images and hypointense on the corresponding ADC maps. Mean diffusion-weighted imaging signal intensity increased and ADC decreased significantly within 30 minutes after embolization (P < 0.001) and remained unchanged until 90 minutes after injury, independent of the embolization method.

CONCLUSIONS

3.0-Tesla diffusion-weighted MRI may help detect acute mesenteric ischemia as early as 30 minutes after vessel occlusion.

Multidetector CT findings in patients with mesenteric ischaemia following cardiopulmonary bypass surgery

OBJECTIVE

To investigate CT findings in patients with pathologically proven mesenteric ischaemia post-cardiopulmonary bypass surgery and compare them with the control group of patients without ischaemia.

METHODS

68 patients were identified by a search of local surgical and pathological databases; these patients met the inclusion criteria of a laparotomy within 1 month of a procedure requiring cardiopulmonary bypass and a CT abdomen/pelvis within 1 week of the pathological diagnosis. Two radiologists independently reviewed the studies, evaluating 17 separate findings relating to the bowel, the vasculature or other structures; consensus was subsequently reached. The diagnostic value of CT findings was assessed using logistic regression.

RESULTS

52 of 68 patients had pathologically proven ischaemia. Portal venous gas, mesenteric venous gas and small bowel faeces sign all had specificities of >0.94 for ischaemia but low sensitivity (<0.27). Differential mural enhancement had high sensitivity (0.92) but poor specificity (0.50). The combination of pneumatosis, bowel loop dilatation and differential mural enhancement predicted bowel ischaemia with a probability of 98%. The hardest signs to interpret based on poor interreader kappa agreement were bowel wall thinning, mesenteric stranding and differential mural enhancement.

CONCLUSION

A combination of CT signs was predictive of ischaemic bowel; however, the more specific findings lacked sensitivity. If clinical suspicion is high for bowel ischaemia, prompt surgical intervention is warranted, regardless of CT findings.

ADVANCES IN KNOWLEDGE

Arterial occlusion was uncommon and venous occlusion was not present, which is supportive of a predominantly non-occlusive aetiology for ischaemia in this patient group.

Intestinal Ischemia: US-CT findings correlations

Background

Intestinal ischemia is an abdominal emergency that accounts for approximately 2% of gastrointestinal illnesses. It represents a complex of diseases caused by impaired blood perfusion to the small and/or large bowel including acute arterial mesenteric ischemia (AAMI), acute venous mesenteric ischemia (AVMI), non occlusive mesenteric ischemia (NOMI), ischemia/reperfusion injury (I/R), ischemic colitis (IC). In this study different study methods (US, CT) will be correlated in the detection of mesenteric ischemia imaging findings due to various etiologies.

Methods

Basing on experience of our institutions, over 200 cases of mesenteric ischemia/infarction investigated with both US and CT were evaluated considering, in particular, the following findings: presence/absence of arterial/venous obstruction, bowel wall thickness and enhancement, presence/absence of spastic reflex ileus, hypotonic reflex ileus or paralitic ileus, mural and/or portal/mesenteric pneumatosis, abdominal free fluid, parenchymal ischemia/infarction (liver, kidney, spleen).

Results

To make an early diagnosis useful to ensure a correct therapeutic approach, it is very important to differentiate between occlusive (arterial,venous) and nonocclusive causes (NOMI). The typical findings of each forms of mesenteric ischemia are explained in the text.

Conclusion

At present, the reference diagnostic modality for intestinal ischaemia is contrast-enhanced CT. However, there are some disadvantages associated with these techniques, such as radiation exposure, potential nephrotoxicity and the risk of an allergic reaction to the contrast agents. Thus, not all patients with suspected bowel ischaemia can be subjected to these examinations. Despite its limitations, US could constitutes a good imaging method as first examination in acute settings of suspected mesenteric ischemia.

Multidetector CT features of mesenteric vein thrombosis

Mesenteric vein thrombosis (MVT) accounts for 5%-15% of all mesenteric ischemic events and is classified as either primary or secondary. Primary MVT is idiopathic, whereas secondary MVT can result from a variety of underlying diseases and risk factors, including primary hypercoagulable states or prothrombotic disorders, myeloproliferative neoplasms, cancer (most frequently of the pancreas or liver), diverse inflammatory conditions, recent surgery, portal hypertension, and miscellaneous causes such as oral contraceptives or pregnancy. Clinical symptoms of MVT are rather nonspecific and are mainly characterized by abdominal pain. The mortality rate for MVT remains high, since even now the diagnosis is often delayed. Multidetector computed tomography (CT) is the modality of choice in this context. Although venous bowel ischemia occurs only infrequently with MVT, radiologists should be familiar with its multidetector CT features. Familiarity with the possible causes of MVT, the underlying pathogenic mechanisms associated with MVT, and the correlation between multidetector CT features and these pathogenic mechanisms is necessary to optimize medical management and improve patient care.

7T μMRI of mesenteric venous ischemia in a rat model: timing of the appearance of findings

OBJECTIVES

The aim of this study is to analyze the chronological development of macroscopic, microscopic and magnetic resonance imaging (MRI) findings in a rat model of Superior Mesenteric Venous (SMV) ligation, and to evaluate the role of MRI in the diagnosis of mesenteric venous thrombosis.

METHODS

Thirty adult Sprague-Dawley rats were used and divided in two different groups that underwent a different surgical model and a different monitoring of ischemic damage. Group I underwent macroscopical and histological observation; Group II underwent 7T μMRI evaluation and histological analysis.

RESULTS

The first alterations occurred 30 min after SMV ligation and progressively worsened until the eighth hour. The morphological and MRI findings showed the same course.

CONCLUSIONS

This study provides a systematic evaluation of early anatomopathological and MRI findings following the SMV ligation. MRI allows to identify the early pathological findings of venous mesenteric ischemia and allows to correlate those to the histopathological features. Our data suggest a relevant role of MRI in the diagnostic management of mesenteric venous thrombosis, allowing to non-invasively identify and characterize the histopathologic findings. So, thanks to these skills, its future application in early diagnosis of human mesenteric venous ischemia is supposable.

[Diffuse and vascular hepatic diseases]

In addition to focal liver lesions, diffuse and vascular disorders of the liver represent a wide spectrum of liver diseases which are from the radiological point of view often difficult or nearly impossible to diagnose. Classical diagnostic methods are computed tomography and magnetic resonance imaging in addition to ultrasound. Diffuse parenchymal damage caused by diseases of various etiologies is therefore difficult to evaluate because it often lacks characteristic morphological features. For hepatic steatosis, hemochromatosis/siderosis as an example of a diffuse storage disease and sarcoidosis and candidiasis as infectious/inflammatory diseases, an image-based diagnosis is appropriate in some cases. For most diffuse liver diseases, however only nonspecific changes are visualized. Vascular pathologies of the liver, such as the Budd-Chiari syndrome and portal vein thrombosis, however, can usually be diagnosed very clearly using radiology and there is also a very effective interventional radiological treatment. Chronic diseases very often culminate in liver cirrhosis which is highly associated with an increased risk of liver cancer.

Clinical value of comprehensive intervention in the management of superior mesenteric artery embolism caused by atrial fibrillation

AIM: To evaluate the clinical value of comprehensive intervention in the management of superior mesenteric artery embolism caused by atrial fibrillation.

METHODS: The clinical data for four patients who had superior mesenteric artery embolism caused by atrial fibrillation and underwent comprehensive intervention at our hospital from 2008 to 2011 were analyzed retrospectively. The comprehensive intervention consisted of transcatheter arterial fibrinolysis/infusion (TAF/TAI), suction embolectomy, percutaneous transluminal angioplasty (PTA) and anticoagulation.

RESULTS: Treatment duration ranged from 6 to 29 hours. Vascular recanalization was achieved in three patients, of whom one died of recurrence. The embolus was moved to the distal branches in one patient. No patients received surgical operation, and no treatment-related complications occurred.

CONCLUSION: Comprehensive intervention is safe and effective in managing superior mesenteric artery embolism caused by atrial fibrillation.

Rapidly aggravated dissecting flap by angiography during percutaneous stent placement for acute isolated superior mesenteric artery dissection

Acutely aggravated dissecting flap and consequent occlusion of the superior mesenteric artery (SMA) by simple contrast passage during initial angiography for percutaneous stent placement is a uncommon event, which usually is not reported. After analysis of many factors that underlie development of such complications, we present herein one case of successful treatment of isolated SMA dissection and its complications with favorable outcomes during 25 months follow-up after percutaneous stent placement.

Acute mesenteric ischemia induced by ligation of porcine superior mesenteric vein: multidetector CT evaluations

RATIONALE AND OBJECTIVES

To evaluate multidetector computed tomography (MDCT) for detecting the early changes and dynamic evolution of acute mesenteric ischemia (AMI) induced by the ligation of superior mesenteric vein (SMV) in an experimental porcine model.

MATERIALS AND METHODS

Twelve pigs were randomly assigned to three experimental groups, and one control group with three pigs in each group. After laparotomy, the SMV was separated and ligated in nine pigs and separated without ligation in three controls. MDCT pre- and postcontrast with arterial, venous, and delayed phase scans, and CT angiography reconstructions of mesenteric vessels were carried out at preoperation, 6 hours, 12 hours, and 18 hours after ligation. The findings of mesenteric vessels, bowel, abdominal cavity at pre- and postoperation, and dynamic evolution were correlated with pathology.

RESULTS

AMI-induced pathological changes were identified in all nine experimental pigs. MDCT angiography clearly delineated main trunk of the SMV, peripheral major and minor tributaries up to brushy vasa recta, and the location and shape of ligations. The early ischemic findings were bowel wall thickening, mesenteric edema, ascites, and pronounced bowel enhancement. Superior mesenteric artery and its major branches appeared spasm with poor filling and delayed and prolonged visualization. SMV and its tributaries were poorly delineated with delayed opacification. We also saw thinning of bowel wall, dilatating bowel with fluid, aggravating mesenteric edema and ascites, and poor enhanced bowel over time.

CONCLUSION

MDCT detects early changes of mesenteric ischemia and its evolution after ligation of porcine SMV, and may find application in early diagnosis of human venous occlusive AMI.

Successful recanalization of acute superior mesenteric artery thrombotic occlusion with primary aspiration thrombectomy

Prompt revascularization of the superior mesenteric artery (SMA) thrombotic occlusion can prevent intestinal infarction and decrease necrosis of the bowel segment. Herein, we describe two cases who underwent successful endovascular recanalization for acute SMA thrombosis using a primary aspiration thrombectomy because of possible consequent laparotomy for survey of bowel viability. The two patients had dramatic pain relief immediately after the procedure and remained symptom-free during the follow-up period.

Small bowel obstruction-who needs an operation? A multivariate prediction model

BACKGROUND

Proper management of small bowel obstruction (SBO) requires a methodology to prevent nontherapeutic laparotomy while minimizing the chance of overlooking strangulation obstruction causing intestinal ischemia. Our aim was to identify preoperative risk factors associated with strangulating SBO and to develop a model to predict the need for operative intervention in the presence of an SBO. Our hypothesis was that free intraperitoneal fluid on computed tomography (CT) is associated with the presence of bowel ischemia and need for exploration.

METHODS

We reviewed 100 consecutive patients with SBO, all of whom had undergone CT that was reviewed by a radiologist blinded to outcome. The need for operative management was confirmed retrospectively by four surgeons based on operative findings and the patient's clinical course.

RESULTS

Patients were divided into two groups: group 1, who required operative management on retrospective review, and group 2 who did not. Four patients who were treated nonoperatively had ischemia or died of malignant SBO and were then included in group 1; two patients who had a nontherapeutic exploration were included in group 2. On univariate analysis, the need for exploration (n = 48) was associated (p < 0.05) with a history of malignancy (29% vs. 12%), vomiting (85% vs. 63%), and CT findings of either free intraperitoneal fluid (67% vs. 31%), mesenteric edema (67% vs. 37%), mesenteric vascular engorgement (85% vs. 67%), small bowel wall thickening (44% vs. 25%) or absence of the "small bowel feces sign" (so-called fecalization) (10% vs. 29%). Ischemia (n = 11) was associated (p < 0.05 each) with peritonitis (36% vs. 1%), free intraperitoneal fluid (82% vs. 44%), serum lactate concentration (2.7 +/- 1.6 vs. 1.3 +/- 0.6 mmol/l), mesenteric edema (91% vs. 46%), closed loop obstruction (27% vs. 2%), pneumatosis intestinalis (18% vs. 0%), and portal venous gas (18% vs. 0%). On multivariate analysis, free intraperitoneal fluid [odds ratio (OR) 3.80, 95% confidence interval (CI) 1.5-9.9], mesenteric edema (OR 3.59, 95% CI 1.3-9.6), lack of the "small bowel feces sign" (OR 0.19, 95% CI 0.05-0.68), and a history of vomiting (OR 4.67, 95% CI 1.5-14.4) were independent predictors of the need for operative exploration (p < 0.05 each). The combination of vomiting, no "small bowel feces sign," free intraperitoneal fluid, and mesenteric edema had a sensitivity of 96%, and a positive predictive value of 90% (OR 16.4, 95% CI 3.6-75.4) for requiring exploration.

CONCLUSION

Clinical, laboratory, and radiographic factors should all be considered when making a decision about treatment of SBO. The four clinical features-intraperitoneal free fluid, mesenteric edema, lack of the "small bowel feces sign," history of vomiting-are predictive of requiring operative intervention during the patient's hospital stay and should be factored strongly into the decision-making algorithm for operative versus nonoperative treatment.

Portal vein thrombosis, revisited

This review article aims to discuss the aetiology, pathophysiology, clinical presentation, diagnostic workup and management of portal vein thrombosis, either as a primary vascular liver disease in adults and children, or as a complication of liver cirrhosis. In addition, indications and limits of anticoagulant therapy are discussed in detail.

[Diagnostics of vascular diseases as a cause for acute abdomen]

Vascular pathologies are rare causes of an acute abdomen. If the cause is a vascular disease a rapid diagnosis is desired as vascular pathologies are associated with high mortality. A differentiation must be made between arterial and venous diseases. An occlusion of the superior mesenteric artery is the most common reason for acute mesenteric ischemia but intra-abdominal arterial bleeding is also of great importance. Venous pathologies include thrombotic occlusion of the portal vein, the mesenteric vein and the vena cava.Multi-detector computed tomography (MDCT) is predestined for the diagnostics of vascular diseases of the abdomen. Using multiphasic contrast protocols enables reliable imaging of the arterial and venous vessel tree and detection of disorders with high sensitivity and specificity. Although conventional angiography has been almost completely replaced by MDCT as a diagnostic tool, it is still of high importance for minimally invasive interventions, for example in the management of gastrointestinal bleeding.

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.

Vascular disorders of the liver

This guideline has been approved by the American Association for the Study of Liver Diseases (AASLD) and represents the position of the association.

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.

Small bowel vascular disorders from arterial etiology and impaired venous drainage

Intestinal ischemia of the small bowel represents an important diagnostic question to answer in an emergency. Although some findings could be appreciated with basic imaging methods, the MDCT as a modern noninvasive imaging method could be effective in evaluating intestinal disease caused by superior mesenteric artery or vein occlusion and making a diagnosis of ischemia from low-flow states. Looking at the features of the parietal layers with knowledge of the pathologic mechanism underlying the changes from the "normality" could be helpful in making a correct, prompt, and effective diagnosis of intestinal ischemia or disease from impaired venous drainage.

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.

Gastrointestinal disorders in elderly patients

Gastrointestinal disorders are common in elderly patients, and the clinical presentation, complications, and management may differ from those in younger patient. Most impairment occurs in the proximal and distal tract of the gastrointestinal system. Swallowing abnormalities with a wide span of symptoms and pelvic floor pathologies involving all the pelvic compartments are common. Acute abdomen, often from small bowel obstruction or mesenteric ischemia, can pose a diagnostic challenge, because a mild clinical presentation may hide serious visceral involvement. In this setting, the radiologist often is asked to suggest the appropriate management options and to guide the management.