Findings in multi-detector row CT with portal phase enhancement in patients with mesenteric venous thrombosis

Insights into acute mesenteric ischaemia: an up-to-date, evidence-based review from a mesenteric stroke centre unit

Radiologists play a central role in the diagnostic and prognostic evaluation of patients with acute mesenteric ischaemia (AMI). Unfortunately, more than half of AMI patients undergo imaging with no prior suspicion of AMI, making identifying this disease even more difficult. A confirmed diagnosis of AMI is ideally made with dynamic contrast-enhanced CT but the diagnosis may be made on portal-venous phase images in appropriate clinical settings. AMI is diagnosed on CT based on the identification of vascular impairment and bowel ischaemic injury with no other cause. Moreover, radiologists must evaluate the probability of bowel necrosis, which will influence the treatment options.AMI is usually separated into different entities: arterial, venous, non-occlusive and ischaemic colitis. Arterial AMI can be occlusive or stenotic, the dominant causes being atherothrombosis, embolism and isolated superior mesenteric artery (SMA) dissection. The main finding in the bowel is decreased wall enhancement, and necrosis can be suspected when dilatation >25 mm is identified. Venous AMI is related to superior mesenteric vein (SMV) thrombosis as a result of a thrombophilic state (acquired or inherited), local injury (cancer, inflammation or trauma) or underlying SMV insufficiency. The dominant features in the bowel are hypoattenuating wall thickening with submucosal oedema. Decreased enhancement of the involved bowel suggests necrosis. Non-occlusive mesenteric ischaemia (NOMI) is related to impaired SMA flow following global hypoperfusion associated with low-flow states. There are numerous findings in the bowel characterised by diffuse extension. An absence of bowel enhancement and a thin bowel wall suggest necrosis in NOMI. Finally, ischaemic colitis is a sub-entity of arterial AMI and reflects localised colon ischaemia-reperfusion injury. The main CT finding is a thickened colon wall with fat stranding, which seems to be unrelated to SMA or inferior mesenteric artery lesions. A precise identification and description of vascular lesions, bowel involvement and features associated with transmural necrosis is needed to determine patient treatment and outcome.

Decoding pylephlebitis: Tracing the path of infected thrombosis and liver abscesses

Pylephlebitis, a septic thrombophlebitis of the portal vein, is an uncommon but serious complication following an abdominal site of infection, most frequently diverticulitis or appendicitis. It has a high mortality rate, yet it commonly presents with unspecific abdominal complaints and fever, making diagnosis by clinical and laboratory examinations alone, impossible. This report highlights the extensive computed tomography (CT) findings of pylephlebitis with multiple hepatic abscesses thought to be secondary to diverticulitis, in a patient presenting with septic shock. Radiological characteristics differentiating the liver lesions from malignancy, and showing the ascending pathway of vascular involvement from the inferior mesenteric vein to portal veins is presented, as well as the search for the primary site of infection. Recognizing and understanding the imaging findings in pylephlebitis is crucial for diagnosis and avoiding delay of appropriate treatment for this otherwise often fatal condition.

Rare, Overlooked, or Underappreciated Causes of Recurrent Abdominal Pain: A Primer for Gastroenterologists

Recurrent abdominal pain is a common reason for repeated visits to outpatient clinics and emergency departments, reflecting a substantial unmet need for timely and accurate diagnosis. A lack of awareness of some of the rarer causes of recurrent abdominal pain may impede diagnosis and delay effective management. This article identifies some of the key rare but diagnosable causes that are frequently missed by gastroenterologists and provides expert recommendations to support recognition, diagnosis, and management with the ultimate aim of improving patient outcomes.

Superior mesenteric vein thrombosis and osteoporotic vertebral fractures

Superior mesenteric vein (SMV) thrombosis is relatively rare disease with unspecific symptoms. Thrombus formation within the SMV eventually leads to congestive intestinal necrosis. In most cases, the lack of specific symptoms makes early diagnosis difficult. Therefore, it is important to suspect the disease and actively investigate it, given a causative factor. Here, we report a case of SMV thrombosis with a novel predisposing factor, compression of SMV by deformed spine, found on contrast medium-enhanced computed tomography. Treatment with intravenous heparin followed by oral anticoagulants resulted in favorable outcome. This is the first picture showing the novel mechanism of SMV thrombus formation relating to spinal deformity. Treating osteoporosis before spinal deformity could prevent SMV thrombosis with such a mechanism.

Endovascular revascularization of acute arterial mesenteric ischemia: report of a 3-year experience from an intestinal stroke center unit

OBJECTIVE

To report the 3-year experience of endovascular revascularization of acute arterial mesenteric ischemia (AMI) from an intestinal stroke center unit (ISCU).

METHOD

All data from patients admitted to the ISCU between January 2016 and January 2019 for arterial AMI who underwent endovascular recanalization were prospectively acquired and retrospectively analyzed. Patient demographics, clinical and laboratory characteristics at presentation, and CT scans were reviewed. The type (thrombolysis, thrombectomy, stenting) and the outcome of endovascular procedures (technical success or failure, complications) were noted. Care pathways were described focusing on post-procedural treatments (surgical revascularization, bowel resection) and the mortality rate was evaluated in subgroups.

RESULTS

Fifty-eight patients (34 men [59%], mean 69 ± 29 years) were included. Endovascular revascularization was technically successful in 51/58 (88%) patients, and 10 (17%) patients had post-procedural complications. Stenting and in situ thrombolysis were performed in most patients (n = 33 and n = 19, respectively). Thirty-two patients (55%) were recurrence-free and required no further treatment after the procedure, while 9 (16%), 5 (9%), and 5 (9%) patients underwent 2nd-line bowel resection, surgical revascularization, or both. Overall, 46 (79%), 45 (78%), and 34 patients (63%) were alive at 3 months, 1 year, and 3 years. No significant difference in survival was found in care pathways or baseline characteristics.

CONCLUSION

Endovascular revascularization is highly feasible for the treatment of arterial AMI, and is associated with an acceptable rate of complications. Results of endovascular revascularization shall only be interpreted as part of a multidisciplinary patient management strategy.

KEY POINTS

• Endovascular revascularization is highly feasible for the treatment of arterial AMI, and is associated with an acceptable rate of complications. • Several techniques are available to perform endovascular revascularization, and their use depends on the cause, the location, and the quality of underlying arteries of patients. • Results of endovascular revascularization shall only be interpreted in relation to its role in an integrated multidisciplinary and patient management strategy.

Cancer-Associated Splanchnic Vein Thrombosis

Splanchnic vein thrombosis (SVT), which includes portal, mesenteric, and splenic vein thrombosis and the Budd-Chiari syndrome, is an infrequent manifestation of venous thromboembolism (VTE). Like typical site VTE, SVT is also frequently associated with cancer, particularly intra-abdominal solid malignancies and myeloproliferative neoplasms (MPNs). The clinical presentation of SVT is nonspecific. Symptoms may be related to the underlying malignancy, and thrombosis is incidentally diagnosed by imaging studies for cancer staging or follow-up in a substantial proportion of cases. The occurrence of SVT predicts worse prognosis in patients with liver or pancreatic cancer and, not uncommonly, SVT may precede the diagnosis of cancer. Therefore, the occurrence of an apparently unprovoked SVT should prompt careful patient evaluation for the presence of an underlying malignancy or MPN. Cancer patients carry a high risk of VTE extension and recurrence and long-term anticoagulant treatment is suggested in the absence of high risk of bleeding. Either LMWH or direct oral anticoagulants (DOACs) are suggested for the treatment of patients with cancer-related SVT, although limited experience is available on the use of DOACs in these settings. Vitamin K antagonists (VKAs) are suggested for the short and long-term treatment of SVT associated with MPN. This review outlines the epidemiological aspects, pathogenesis, risk factors, and diagnosis of cancer-associated SVT, and addresses questions regarding the management of this challenging condition.

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.

Pearls, Pitfalls, and Conditions that Mimic Mesenteric Ischemia at CT

Acute mesenteric ischemia (AMI) is a life-threatening condition with a high mortality rate. The diagnosis of AMI is challenging because patient symptoms and laboratory test results are often nonspecific. A high degree of clinical and radiologic suspicion is required for accurate and timely diagnosis. CT angiography of the abdomen and pelvis is the first-line imaging test for suspected AMI and should be expedited. A systematic "inside-out" approach to interpreting CT angiographic images, beginning with the bowel lumen and proceeding outward to the bowel wall, mesentery, vasculature, and extraintestinal viscera, provides radiologists with a practical framework to improve detection and synthesis of imaging findings. The subtypes of AMI are arterial and venoocclusive disease, nonocclusive ischemia, and strangulating bowel obstruction; each may demonstrate specific imaging findings. Chronic mesenteric ischemia is more insidious at onset and almost always secondary to atherosclerosis. Potential pitfalls in the diagnosis of AMI include mistaking pneumatosis as a sign that is specific for AMI and not an imaging finding, misinterpretation of adynamic ileus as a benign finding, and pseudopneumatosis. Several enterocolitides can mimic AMI at CT angiography, such as inflammatory bowel disease, infections, angioedema, and radiation-induced enterocolitis. Awareness of pitfalls, conditions that mimic AMI, and potential distinguishing clinical and imaging features can assist radiologists in making an early and accurate diagnosis of AMI. ^©RSNA, 2020.

Contrast-Enhanced CT for the Diagnosis of Acute Mesenteric Ischemia

OBJECTIVE. The purpose of this article is to provide an overview of the diagnostic and prognostic roles of CT in the management of acute mesenteric ischemia. CONCLUSION. Acute mesenteric ischemia is defined as inadequate blood supply to the gastrointestinal tract resulting in ischemic and inflammatory injury. The prognosis is poor without treatment. Contrast-enhanced CT has become the cornerstone of diagnosis to identify features of vascular disorders and of intestinal ischemic injury and to visualize bowel necrosis.

ACG Clinical Guideline: Disorders of the Hepatic and Mesenteric Circulation

Disorders of the mesenteric, portal, and hepatic veins and mesenteric and hepatic arteries have important clinical consequences and may lead to acute liver failure, chronic liver disease, noncirrhotic portal hypertension, cirrhosis, and hepatocellular carcinoma. Although literature in the field of vascular liver disorders is scant, these disorders are common in clinical practice, and general practitioners, gastroenterologists, and hepatologists may benefit from expert guidance and recommendations for management of these conditions. These guidelines represent the official practice recommendations of the American College of Gastroenterology. Key concept statements based on author expert opinion and review of literature and specific recommendations based on PICO/GRADE analysis have been developed to aid in the management of vascular liver disorders. These recommendations and guidelines should be tailored to individual patients and circumstances in routine clinical practice.

Quantitative investigation of vascular response to mesenteric venous thrombosis using large-field-of-view photoacoustic microscopy

Mesenteric venous thrombosis (MVT) is one of major causes leading to severe mesenteric ischemia. Vascular network plays an important role during the occurrence and development of MVT. However, there lacks an appropriate imaging method, which features advanced volumetric resolving capability, superior sensitivity to hemoglobin, and ultra-large field-of-view (FOV), to investigate vascular response of MVT. In this study, we developed and applied a large-FOV optical resolution photoacoustic microscopy to quantify the vascular response during the entire course of two different MVT models in which we ligated the superior mesenteric vein and inferior mesenteric vein, respectively. Furthermore, we developed a quantitative algorithm to derive total vascular length, relative concentration of total hemoglobin and vascular density over the FOV to reveal different vascular responses in different MVT models.

Acute mesenteric ischaemia: imaging and intervention

Acute mesenteric ischaemia (AMI) is an abdominal emergency in which an acute reduction in mesenteric arterial supply threatens bowel viability and may result in bowel infarction, perforation, and death. Despite improvements in diagnosis and treatment over recent decades, mortality rates in AMI remain very high. This article discusses the aetiological classification, pathophysiology, and clinical aspects of AMI. The specific imaging characteristics of each aetiological type of AMI are detailed and the role of different imaging methods in the diagnosis of AMI is discussed. Surgery is the established treatment of choice for AMI, but there is increasing use of endovascular techniques in treating AMI in cases where there are no clinical features of peritonism or radiological evidence of irreversible ischaemia. This article reviews the evidence for different diagnostic and management strategies for patients with AMI and discusses the advantages and disadvantages of surgical and endovascular treatments. Endovascular techniques have been reported to have high technical success rates and favourable outcomes when compared to open surgery; however, patient selection bias and a paucity of data limit the conclusions that can be drawn.

Post-traumatic superior mesenteric venous thrombosis with subsequent extension to the portal vein

Acute superior mesenteric vein thrombosis was first described in 1935 by Warren and Eberhardt. It is a potentially life-threatening condition, as it can lead to bowel ischemia and, ultimately, infarction. Its etiology may be primary or secondary to acquired prothrombotic conditions. Early recognition of mesenteric venous thrombosis is important, but can be challenging due to its nonspecific clinical presentation. Contrast-enhanced computed tomography is currently the gold standard for diagnosis. Systemic anticoagulation and surgical resection of the necrotic segment are the two main treatments. Here, we describe a case of acute post-traumatic superior mesenteric vein thrombosis, which was treated with systemic anticoagulation and resection of the ischemic bowel segment, with subsequent extension of the thrombosis to the portal vein.

Improved Prognosis and Low Failure Rate with Anticoagulation as First-Line Therapy in Mesenteric Venous Thrombosis

BACKGROUND

Monotherapy with anticoagulation has been considered as first-line therapy in patients with mesenteric venous thrombosis (MVT). The aim of this study was to evaluate outcome, prognostic factors, and failure rate of anticoagulation as monotherapy, and to identify when bowel resection was needed.

METHODS

Retrospective study of consecutive patients with MVT diagnosed between 2000 and 2015.

RESULTS

The overall incidence rate of MVT was 1.3/100,000 person-years. Among 120 patients, seven died due to autopsy-verified MVT without bowel resection and 15 underwent immediate bowel resection without prior anticoagulation therapy. The remaining 98 patients received anticoagulation monotherapy, whereof 83 (85%) were treated successfully. Fifteen patients failed on anticoagulation monotherapy, of whom seven underwent bowel resection and eight endovascular therapy. Endovascular therapy was followed by bowel resection in three patients. Two late bowel resections were performed due to intestinal stricture. The 30-day mortality rate was 19.0% in the former (2000-2007) and 3.2% in the latter (2008-2015) part of the study period (p = 0.006). Age ≥75 years (OR 12.4, 95% CI [2.5-60.3]), management during the former as opposed to the latter time period (OR 8.4, 95% CI [1.3-54.7]), and renal insufficiency at admission (OR 8.0, 95% CI [1.2-51.6]) were independently associated with increased mortality in multivariable analysis.

CONCLUSIONS

Short-term prognosis in patients with MVT has improved. Contemporary data show that monotherapy with anticoagulation is an effective first choice in MVT patients.

Evaluation of direct oral anticoagulants and vitamin K antagonists in mesenteric venous thrombosis

BACKGROUND/AIM

Mesenteric venous thrombosis is a rare lethal disease. The main aim of the present study was to evaluate clinical efficacy and safety of direct oral anticoagulants and vitamin K antagonists in mesenteric venous thrombosis patients.

METHODS

Retrospective study of 102 mesenteric venous thrombosis patients treated between 2004 and 2017 at a center with a conservative medical first approach. Median clinical follow-up was 4 years.

RESULTS

Computed tomography showed successful recanalization of thrombosis in 71% of patients on vitamin K antagonists and 69% of patients on direct oral anticoagulants ( p = 0.88). Overall major and esophageal variceal bleeding rate was 14.7% and 2.9%, respectively. No difference in major bleeding ( p = 0.54) was found between vitamin K antagonists and direct oral anticoagulants. No mesenteric venous thrombosis recurrence occurred during follow-up, and one venous thromboembolism occurred after cessation of anticoagulation.

CONCLUSION

Anticoagulation with direct oral anticoagulants and vitamin K antagonists was efficient in patients with mesenteric venous thrombosis. Bleeding complications was a concern during treatment in both groups.

Approach to thrombosis at unusual sites: Splanchnic and cerebral vein thrombosis

Splanchnic vein thrombosis (SVT) and cerebral vein thrombosis (CVT) are two manifestations of unusual site venous thromboembolism (VTE). SVT includes thrombosis in the portal, mesenteric or splenic veins, and the Budd-Chiari syndrome. CVT encompasses thrombosis of the dural venous sinuses and thrombosis of the cerebral veins. Unusual site VTE often represents a diagnostic and therapeutic challenge because of the heterogeneity in clinical presentation, the limited evidence available in the literature on the acute and long-term prognosis of these diseases, and the lack of large randomized controlled trials evaluating different treatment options. This narrative review describes the approach to patients with SVT or CVT by examining the diagnostic process, the assessment of potential risk factors and the appropriate anticoagulant treatment.

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.

Imaging Diagnosis of Splanchnic Venous Thrombosis

Splanchnic vein thrombosis (SVT) is a broad term that includes Budd-Chiari syndrome and occlusion of veins that constitute the portal venous system. Due to the common risk factors involved in the pathogenesis of these clinically distinct disorders, concurrent involvement of two different regions is quite common. In acute and subacute SVT, the symptoms may overlap with a variety of other abdominal emergencies while in chronic SVT, the extent of portal hypertension and its attendant complications determine the clinical course. As a result, clinical diagnosis is often difficult and is frequently reliant on imaging. Tremendous improvements in vascular imaging in recent years have ensured that this once rare entity is being increasingly detected. Treatment of acute SVT requires immediate anticoagulation. Transcatheter thrombolysis or transjugular intrahepatic portosystemic shunt is used in the event of clinical deterioration. In cases with peritonitis, immediate laparotomy and bowel resection may be required for irreversible bowel ischemia. In chronic SVT, the underlying cause should be identified and treated. The imaging manifestations of the clinical syndromes resulting from SVT are comprehensively discussed here along with a brief review of the relevant clinical features and therapeutic approach.

Mesenteric ischemia

PURPOSE OF REVIEW

Diagnosis of acute mesenteric ischemia in the early stages is now possible with modern computed tomography (CT), using intravenous contrast enhancement and imaging in the arterial and/or portal venous phase. The availability of CT around the clock means that more patients with acute mesenteric ischemia may be treated with urgent intestinal revascularization.

RECENT FINDINGS

The establishment of a hybrid operation room is most important to be able to perform explorative laparotomy for evaluation of the extent of mesenteric ischemia and successful intestinal revascularization. Endovascular recanalization and stenting has become an important alternative, especially in patients with both acute and chronic thrombotic superior mesenteric artery (SMA) occlusion. Aspiration embolectomy, thrombolysis and open surgical embolectomy, followed by on-table angiography, are the treatment options for embolic SMA occlusion. Endovascular therapy may be an option in the few patients with mesenteric venous thrombosis who do not respond to anticoagulation therapy. The concept of damage-control surgery is recommended after intestinal revascularization.

SUMMARY

Intestinal revascularization in patients with arterial occlusive mesenteric ischemia reduces bowel morbidity and mortality. Observational studies report that both endovascular and open vascular therapy options are effective, but endovascular technique may be preferred in these often elderly and fragile patients.

D-dimer as an early marker of severity in patients with acute superior mesenteric venous thrombosis

No early serum marker of disease severity contributes to the treatment decision-making process of acute superior mesenteric venous thrombosis (ASMVT). This study aims to assess the value of serum D-dimer level in the first 3 days after admission as a severity marker of ASMVT patients. From May 2010 to June 2014, 50 consecutive patients of ASMVT were enrolled in this observational study. The serum D-dimer level was measured on a daily basis during the first 3 days after admission as well as other laboratory-testing parameters, clinical score, and outcome variables recorded during the same period. The maximum and mean D-dimer values were analyzed and compared with other potential markers for prediction of multiple-organ dysfunction syndrome (MODS) and short-bowel syndrome (SBS). The correlation of D-dimer level with other potential severity markers and inflammation parameters were also studied. Both maximum and mean D-dimer level during the first 3 days of admission were significantly higher in patients with several clinical variables such as death within 30 days, bowel resection, sepsis, abdominal compartment syndrome, MODS, and SBS. In addition, serum D-dimer level showed precise prediction for MODS and SBS, greater than L-lactate and intestinal-type fatty acid-binding protein (I-FABP). The D-dimer level was correlated well with L-lactate, I-FABP, and APACHE II score on the first 3 days of admission. Poor correlation of D-dimer level and inflammation parameters, white blood cell count, and C-reactive protein level, was detected. D-dimer level could be an effective, early, and specific serum marker indicating the clinical evolution and outcome of ASMVT.

Acute mesenteric venous thrombosis with a vaginal contraceptive ring

Mesenteric venous thrombosis is a rare cause of abdominal pain, which if left untreated may result in bowel infarction, peritonitis and death. The majority of patients with this illness have a recognizable, predisposing prothrombotic condition. Oral contraceptives have been identified as a predisposing factor for mesenteric venous thrombosis in reproductive-aged women. In the last fifteen years new methods of hormonal birth control have been introduced, including a transdermal patch and an intravaginal ring. In this report, we describe a case of mesenteric venous thrombosis in a young woman caused by a vaginal contraceptive ring.

Modern treatment of acute mesenteric ischaemia

BACKGROUND

Diagnosis of acute mesenteric ischaemia in the early stages is now possible with modern computed tomography (CT), using intravenous contrast enhancement and imaging in the arterial and/or portal venous phase. The availability of CT around the clock means that more patients with acute mesenteric ischaemia may be treated with urgent intestinal revascularization.

METHODS

This was a review of modern treatment strategies for acute mesenteric ischaemia.

RESULTS

Endovascular therapy has become an important alternative, especially in patients with acute thrombotic superior mesenteric artery (SMA) occlusion, where the occlusive lesion can be recanalized either antegradely from the femoral or brachial artery, or retrogradely from an exposed SMA after laparotomy, and stented. Aspiration embolectomy, thrombolysis and open surgical embolectomy, followed by on-table angiography, are the treatment options for embolic SMA occlusion. Endovascular therapy may be an option in the few patients with mesenteric venous thrombosis who do not respond to anticoagulation therapy. Laparotomy is needed to evaluate the extent and severity of visceral organ ischaemia, which is treated according to the principles of damage control surgery.

CONCLUSION

Modern treatment of acute mesenteric ischaemia involves a specialized approach that considers surgical and, increasingly, endovascular options for best outcomes.

Portal vein aneurysms: imaging manifestations and clinical significance

This article will review the computed tomography (CT) findings in patients with portal vein aneurysms (including presentation of several case examples) and discuss imaging criteria and management options. Given the extreme rarity of portal vein aneurysms, as well as a lack of familiarity with the entity on the part of radiologists, the diagnosis can often be overlooked. Appreciation of the most commonly used diagnostic criteria, as well as the role of CT in the appropriate follow-up of these patients, is critical in ensuring appropriate management. In particular, the significance of these aneurysms must be appreciated in the emergency setting, as portal vein aneurysms can rarely present with symptoms of abdominal pain and other complications (such as thrombosis, portal hypertension, rupture, embolism, and compression of the duodenum and inferior vena cava) making surgical repair necessary.

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.

Mesenteric venous thrombosis

The prevalence of mesenteric venous thrombosis has increased over the past 2 decades with the routine use of contrast-enhanced computed tomography (CT) in patients presenting with abdominal pain and those with portal hypertension. Concurrent with increasing recognition, routine and frequent use of anticoagulation has reduced the need for surgical intervention and improved outcome in these patients. Acute thrombosis often presents with abdominal pain, whereas chronic disease manifests either as an incidental finding on CT or with features of portal hypertension. Contrast-enhanced CT diagnoses about 90% of cases. The presence of collateral circulation and cavernoma around a chronically thrombosed vein differentiates chronic from acute disease. The superior mesenteric vein is often involved, whereas involvement of the inferior mesenteric vein is rare. Associated portal venous thrombosis can be seen if the disease originates in the major veins instead of the small vena rectae. Thrombophilia and local abdominal inflammatory conditions are common causes. Management is aimed at preventing bowel infarction and recurrent thrombosis. Anticoagulation, the mainstay of management, has also been safely used in patients with cirrhosis and portal hypertension. This review discusses the pathogenesis of thrombosis of mesenteric veins, the diagnosis and differentiation from arterial ischemia, the emergence of the JAK2 (Janus kinase 2) sequence variation as a marker of thrombophilia and myelodysplastic neoplasms, and new anticoagulants. Algorithms for the management of acute and chronic mesenteric venous thrombosis are provided to help readers understand and remember the approach to the management of acute and chronic mesenteric venous thrombosis.

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.

Mesenteric venous thrombosis

First differentiated from arterial causes of acute mesenteric ischemia 75 years ago, acute mesenteric venous thrombosis (MVT) is an uncommon disorder with non-specific signs and symptoms, the diagnosis of which requires a high index of suspicion. The location, extent, and rapidity of thrombus formation determine whether intestinal infarction ensues. Etiologies, when identified, usually can be separated into local intra-abdominal factors and inherited or acquired hypercoagulable states. The diagnosis is most often made by contrast-enhanced computed tomography, though angiography and exploratory surgery still have important diagnostic as well as therapeutic roles. Anticoagulation prevents clot propagation and is associated with decreased recurrence and mortality. Thrombectomy and thrombolysis may preserve questionably viable bowel and should be considered under certain circumstances. Evidence of infarction mandates surgery and resection whenever feasible. Although its mortality rate has fallen over time, acute MVT remains a life-threatening condition requiring rapid diagnosis and aggressive management. Chronic MVT may manifest with complications of portal hypertension or may be diagnosed incidentally by noninvasive imaging. Management of chronic MVT is directed against variceal hemorrhage and includes anticoagulation when appropriate; mortality is largely dependent on the underlying risk factor.