Noninvasive assessment of portomesenteric venous thrombosis: current concepts and imaging strategies

Intestinal Obstruction as Initial Presentation of Idiopathic Portal and Mesenteric Venous Thrombosis: Diagnosis, Management, and Literature Review

It is quite common for portal vein thrombosis to occur in subjects who present predisposing conditions such as cirrhosis, hepatobiliary malignancies, infectious or inflammatory abdominal diseases, or hematologic disorders. The incidence of idiopathic portal vein thrombosis in non-cirrhotic patients remains low, and despite the intensive workup that is performed in these cases, in up to 25% of cases, there is no identifiable cause. If portal vein thrombosis is untreated, complications arise and include portal hypertension, cavernous transformation of the portal vein, gastroesophageal and even small intestinal varices, septic thrombosis, or intestinal ischemia. However, intestinal ischemia develops as a consequence of arterial thrombosis or embolism, and the thrombosis of the mesenteric vein accounts for about 10% of cases of intestinal ischemia. Although acute superior mesenteric vein thrombosis can cause acute intestinal ischemia, its chronic form is less likely to cause acute intestinal ischemia, considering the possibility of developing collateral drainage. Ileus due to mesenteric venous thrombosis is rare, and only a small number of cases have been reported to date. Most patients experience a distinct episode of acute abdominal pain due to ischemia, and in the second phase, they develop an obstruction/ileus. Acute superior mesenteric venous thrombosis is a rare condition that is still associated with a high mortality rate. The management of such cases of superior mesenteric venous thrombosis is clinically challenging due to their insidious onset and rapid development. A prompt and accurate diagnosis followed by a timely surgical treatment is important to save patient lives, improve the patient survival rate, and conserve as much of the patient's bowel as possible, thus leading to fewer sequelae.

The Role of Thromboprophylaxis in Patients with Portal Vein Thrombosis: A Life-Threatening Complication after Laparoscopic Sleeve Gastrectomy Following 8 Years of Experience in a Bariatric Center of Excellence

Porto-mesenteric vein thrombosis (PVMT) is a rare but life-threatening complication after laparoscopic sleeve gastrectomy (LSG). Laparoscopic sleeve gastrectomy (LSG) is considered the most common procedure for efficiently realizing weight loss and treating obesity-related co-morbidities. This study aimed to shed light on this relatively rare complication by presenting a series of patients who developed PMVT after LSG in light of the need to change the specific protocol of thromboprophylaxis in bariatric patients. We proposed to answer two questions: whether we should perform a thrombophilia workup as a standard practice and whether we should extend chemoprophylaxis to more than 3 weeks among all bariatric patients. This study also aimed to investigate the possible risk factors and eventually present our updated protocol for PMVT management and prophylaxis.

Superior Mesenteric Vein Thrombosis in a Pediatric Patient: Case Report and Review of the Literature

ABSTRACT

Patients with inflammatory bowel disease are at increased risk of thromboembolism. There are various sites for thromboembolism including the cerebral, limbs, abdominal vessels, retina, and lungs. Here, we report a case of a 17-year-old patient with a history of Crohn disease presenting with abdominal pain. Upon further evaluation, the patient was found to have mesenteric vein thrombosis, which was discovered on computed tomographic scan. Potential causes, contributing factors, diagnosis, and treatment are discussed here.

Splenic volume and splenic vein diameter are independent pre-operative risk factors of portal vein thrombosis after splenectomy: a retrospective cohort study

BACKGROUND

Portal vein thrombosis (PVT) is a common complication following splenectomy. It affects between 5 and 55% of patients undergoing surgery with no clearly defined pre-operative risk factors. The aim of this study was to determine the pre-operative risk factors of PVT.

PATIENTS AND METHOD

Single centre, retrospective study of data compiled for every consecutive patient who underwent splenectomy at Toulouse University Hospital between January 2009 and January 2019. Patients with pre- and post-surgical CT scans have been included.

RESULTS

149 out of 261 patients were enrolled in the study (59% were males, mean age 52 years). The indications for splenectomy were splenic trauma (30.9%), malignant haemopathy (26.8%) and immune thrombocytopenia (8.0%). Twenty-nine cases of PVT (19.5%) were diagnosed based on a post-operative CT scan performed on post-operative day (POD) 5. Univariate analysis identifies three main risk factors associated with post-operative PVT: estimated splenic weight exceeding 500 g with an OR of 8.72 95% CI (3.3-22.9), splenic vein diameter over 10 mm with an OR of 4.92 95% CI (2.1-11.8) and lymphoma with an OR of 7.39 (2.7-20.1). The role of splenic vein diameter with an OR of 3.03 95% CI (1.1-8.6), and splenic weight with an OR of 5.22 (1.8-15.2), as independent risk factors is confirmed by multivariate analysis. A screening test based on a POD 5 CT scan with one or two of these items present could indicate sensitivity of 86.2% and specificity of 86.7%.

CONCLUSION

This study suggests that pre-operative CT scan findings could predict post-operative PVT. A CT scan should be performed on POD 5 if a risk factor has been identified prior to surgery.

Acute splanchnic vein thrombosis in patients with COVID-19: A systematic review

There is increasing evidence that coronavirus disease 2019 (COVID-19) is associated with a significant risk of venous thromboembolism. While information are mainly available for deep vein thrombosis of the lower limb and pulmonary embolism, scarce data exist regarding acute splanchnic vein thrombosis (SVT) in this setting. PubMed, EMBASE and Google Scholar English-language articles published up to 30 January 2021 on SVT in COVID-19 were searched. Overall, 21 articles reporting equal number of patients were identified. 15 subjects presented with portal vein thrombosis, 11 with mesenteric vein thrombosis, four with splenic vein thrombosis, and two with Budd-Chiari syndrome. Male sex was prevalent (15 patients), and median age was 43 years (range 26-79 years). Three patients had a history of liver disease, while no subject had known myeloproliferative syndrome. Clinical presentation included mainly gastrointestinal symptoms. Anticoagulation was started in 16 patients. Three patients underwent bowel resection. Ten subjects developed gastric or bowel ischemia, seven of whom underwent bowel resection, and four died after SVT diagnosis. Although rare, SVT should be seen as a complication of COVID-19. Patients with severe gastrointestinal symptoms should be screened for SVT, as rapid recognition and correct management are essential to improve the outcome of these patients.

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.

Causes and Management of Non-cirrhotic Portal Hypertension​

PURPOSE OF THE REVIEW

Non-cirrhotic portal hypertension (NCPH) includes a heterogeneous group of conditions. The aim of this paper is to make an overview on the denominations, diagnostical features and management of porto-sinusoidal vascular disease (PSVD) and chronic portal vein thrombosis (PVT) being the main causes of NCPH in the Western world.

RECENT FINDINGS

The management of NCPH consists in the treatment of associated diseases and of portal hypertension (PH). PH due to PSVD or PVT is managed similarly to PH due to cirrhosis. TIPS placement and liver transplantation are considerable options in patients with refractory variceal bleeding/ascites and with progressive liver failure. Anticoagulation is a cornerstone both in the treatment of thrombosis in PSVD and in the prevention of thrombosis recurrence in patients with portal cavernoma. Physicians should be aware of the existence of PSVD and chronic PVT and actively search them in particular settings. To now, the management of portal hypertension-related complications in NCPH is the same of those of cirrhosis. Large cooperative studies on the natural history of NCPH are necessary to better define its management.

Portomesenteric Venous Thrombosis in Patients Undergoing Surgery for Medically Refractory Ulcerative Colitis

BACKGROUND

Portomesenteric venous thrombosis (PMVT) is an under-recognized complication of colorectal surgery. The aim of this study was to describe the rate and risk factors for PMVT in patients undergoing surgery for medically refractory ulcerative colitis (UC).

METHODS

A retrospective review of medically refractory UC patients who underwent surgery between January 2010 and December 2016 at a single tertiary care center was conducted. PMVT was defined as thrombus within the portal, splenic, superior, or inferior mesenteric vein on postoperative abdominal computed tomography scans. Factors associated with PMVT on univariable analysis were tested in multivariable analysis. Clinical relevance of risk factors was examined with receiver operating characteristic curves and Kaplan-Meier curves.

RESULTS

A total of 434 patients were identified. Postoperative venous thromboembolism (VTE) prophylaxis was administered to 428 (98.5%) inpatients for a mean duration of 7.7 ± 0.17 days. PMVT developed in 36 (8.3%) patients a mean interval of 55.3 ± 10.8 days after index surgery. The majority of PMVT occurred after subtotal colectomy, and the most common initial symptom was abdominal pain. Preoperative C-reactive protein (CRP) was associated with PMVT (odds ratio, 1.01; 95% confidence interval, 1.00-1.02; P = 0.01), and the optimal predictive CRP threshold was 45 mg/L. The rate of PMVT development was greater for patients with CRP >45 mg/L (P = 0.01).

CONCLUSIONS

PMVT can present as abdominal pain and occur multiple weeks after discharge. Further studies are needed to identify the appropriate postoperative outpatient thrombosis prophylaxis regimen for at-risk patients.

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.

[Vascular causes of clinically unclear acute abdomen]

CLINICAL ISSUE

Vascular abnormalities are a rare cause of an acute abdomen. They include arterial bleeding and ischemia, the latter being either in the arterial or venous system. The most common cause of an acute ischemic abdomen is acute mesenteric ischemia caused by a thromboembolic occlusion of the superior mesenteric artery, followed by thrombotic occlusion of the portal vein, the mesenteric vein as well as the hepatic veins and the suprahepatic part of the inferior vena cava. In the case of an acute abdomen due to internal bleeding, all abdominal arteries can be the source but most common are ruptures of aortic aneurysms and inflammatory-driven bleeding from the superior mesenteric artery.

PRACTICAL RECOMMENDATIONS

Due to the high mortality, vascular causes should be diagnosed as soon as possible. For this purpose, computed tomography (CT) has evolved into the preferred tool due to its high availability and speed. To differentiate various vascular causes of an acute abdomen, it is important to incorporate a CT protocol without contrast media as well as contrast-enhanced series in arterial and venous phases. Conventional angiography has been replaced by CT for the diagnosis of vascular pathologies causing an acute abdomen; however, it plays an increasing role in the treatment of these pathologies.

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.

Screening for thrombophilia does not identify patients at risk of portal or splenic vein thrombosis following laparoscopic splenectomy

BACKGROUND

Portal and/or splenic vein thrombosis (PSVT) is a potentially lethal complication of splenectomy for hematologic disease. Known risk factors for PSVT include malignancy and splenomegaly. While these patients are believed to be hypercoagulable, the specific mechanism is unclear. The aim of this study is to evaluate whether specific acquired prothrombotic risk factors contribute to the development of PSVT following laparoscopic splenectomy (LS).

METHODS

Consecutive patients undergoing LS were prospectively studied between 2005 and 2013. Preoperatively, patients were screened for prothrombotic states and surveillance duplex ultrasonography was performed between 1 week and 1 month postoperatively to assess for PSVT. The association between baseline prothrombotic disorders and PSVT was explored using descriptive statistics.

RESULTS

Sixty-eight patients were included in the analysis, and 17 (25 %) of these developed PSVT. There were no differences in patients with and without PSVT with respect to age, body mass index, gender or surgical time. Preoperative spleen size, as determined by diagnostic imaging, and intraoperative blood transfusion were associated with PSVT. Seven of 9 patients (78 %) with massive splenomegaly (>20 cm) developed PSVT compared with 4 of 13 patients (31 %) with moderate splenomegaly (15-20 cm) and 6 of 45 patients (13 %) without (p < 0.001). Abnormalities in baseline prothrombotic screening tests were common, with 52 patients (75 %) demonstrating at least one; however, none were associated with the development of PSVT.

CONCLUSION

In patients scheduled for LS, screening for prothrombotic states is not useful to identify patients at risk of development of PSVT. Preoperative spleen size and blood transfusion were predictive of PSVT formation.

Portal vein thrombosis

Portal vein thrombosis (PVT) is the blockage or narrowing of the portal vein by a thrombus. It is relatively rare and has been linked with the presence of an underlying liver disease or prothrombotic disorders. We present a case of a young male who presented with vague abdominal symptoms for approximately one week. Imaging revealed the presence of multiple nonocclusive thrombi involving the right portal vein, the splenic vein, and the left renal vein, as well as complete occlusion of the left portal vein and the superior mesenteric vein. We discuss pathogenesis, clinical presentation, and management of both acute and chronic thrombosis. The presence of PVT should be considered as a clue for prothrombotic disorders, liver disease, and other local and general factors that must be carefully investigated. It is hoped that this case report will help increase awareness of the complexity associated with portal vein thrombosis among the medical community.

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.

Abdominal thromboses of splanchnic, renal and ovarian veins

Thromboses of abdominal veins outside the iliac-caval axis are rare but clinically relevant. Early deaths after splanchnic vein thrombosis occur in 5-30% of cases. Sequelae can be liver failure or bowel infarction after splanchnic vein thrombosis, renal insufficiency after renal vein thrombosis, ovarian infarction after ovarian vein thrombosis. Local cancer or infections are rare in Budd-Chiari syndrome, and common for other sites. Inherited thrombophilia is detected in 30-50% of patients. Myeloproliferative neoplasms are the main cause of splanchnic vein thrombosis: 20-50% of patients have an overt myeloproliferative neoplasm and/or carry the molecular marker JAK2 V617F. Renal vein thrombosis is closely related to nephrotic syndrome; finally, ovarian vein thrombosis can complicate puerperium. Heparin is used for acute treatment, sometimes in conjunction with systemic or local thrombolysis. Vitamin K-antagonists are recommended for 3-6 months, and long-term in patients with Budd-Chiari syndrome, unprovoked splanchnic vein thrombosis, or renal vein thrombosis with a permanent prothrombotic state such as nephrotic syndrome.

Diagnosis of portal vein tumor thrombus: the combination of enhanced multislice spiral computed tomography and portography

AIM: To evaluate the value of combined enhanced 16-slice spiral CT and portography reconstruction in the diagnosis of portal vein tumor thrombus.

METHODS: Fifty-two patients with portal vein tumor thrombus underwent 16-slice spiral CT examination. A plain scan and triple-phase enhanced scans (arterial phase, portal venous phase, and equilibrium phase) were performed. Scanning parameters were as follows: a slice thickness of 2.5 mm, a reconstruction interval of 0.625 mm, a flow rate of 3.5-4 mL/s, 80-100 mL of contrast agent, and scan time of 25-30 s, 45-60 s, and 120 s, respectively. Image reformation, including volume rendering (VR), multiplanar reformation (MPR) and maximum intensity projection (MIP), was performed by one radiologist. Two radiologists assessed the scope, shape and collateral vessels of the thrombus.

RESULTS: Thirty-five cases (67.3%) of portal vein tumor thrombus showed inhomogeneous enhancement in the arterial phase, and 47 cases (90.4%) had the enlarged portal vein and filling defect. Enhancement of the vessel wall was seen in 19 cases (36.5%), collateral circulation formation in 13 cases (25%), compression of the portal vein in 13 cases (25%), and arterioportal fistula in 6 cases (11.5%). Different portal vein reconstruction techniques showed different number of cases of portal vein tumor thrombus: 52 (100%) by MPR, 43 (82.7%) by MIP, 39 (75%) by VR.

CONCLUSION: The combination of enhanced CT and portography reconstruction can reveal portal vein tumor thrombus completely and has important clinical value.

Acute mesenteric ischemia

OPINION STATEMENT

Acute mesenteric ischemia is caused by a critical reduction in intestinal blood flow that frequently results in bowel necrosis and is associated with a high mortality. Clinicians must maintain a high index of suspicion because a prompt diagnosis and early aggressive treatment before the onset of bowel infarction results in reduced mortality. Medical management includes aggressive rehydration and the use of antibiotics, anticoagulation, vasodilators, and inhibitors of reperfusion injury. If acute mesenteric ischemia is suspected, early angiography is imperative, as it permits accurate diagnosis and possible therapeutic intervention. Therapeutic options during angiography depend on the cause of ischemia and include administering intra-arterial vasodilators and/or thrombolytic agents and angioplasty with or without stent placement. If interventional techniques are not possible or if the patient presents with suspicion of bowel infarction, surgery is warranted. Surgical techniques include superior mesenteric artery embolectomy or visceral artery bypass, which should be used before bowel resection to ensure only resection of nonviable bowel.

Splanchnic vein thrombosis: clinical presentation, risk factors and treatment

The term splanchnic vein thrombosis encompasses Budd-Chiari syndrome (BCS), extrahepatic portal vein obstruction (EHPVO), and mesenteric vein thrombosis; the simultaneous involvement of additional regions is frequent, and clinical presentations and risk factors may be shared. The annual incidence of BCS and isolated mesenteric vein thrombosis is less than one per million individuals, while the incidence of EHPVO is about four per million; autopsy studies, however, suggest higher numbers. Current advances in non-invasive vascular imaging allow for the identification of chronic or asymptomatic forms. Risk factors can be local or systemic. A local precipitating factor is rare in BCS, while it is common in patients with portal vein thrombosis. Chronic myeloproliferative neoplasms (MPN) are the leading systemic cause of splanchnic vein thrombosis, and are diagnosed in half the BCS patients and one-third of the EHPVO patients. The molecular marker JAK2 V617F is detectable in a large majority of patients with overt MPN, and up to 40% of patients without overt MPN. Inherited thrombophilia is present in at least one-third of the patients, and the factor V Leiden or the prothrombin G20210A mutations are the most common mutations found in BCS or EHPVO patients, respectively. Multiple factors are present in approximately one-third of the patients with BCS and two-thirds of the patients with portal vein thrombosis. Immediate anticoagulation with heparin is used to treat patients acutely. Upon clinical deterioration, catheter-directed thrombolysis or transjugular intrahepatic portosystemic shunt is used in conjunction with anticoagulation. Long-term oral anticoagulation with vitamin K-antagonists (VKA) is recommended in all BCS patients, and in the patients with a permanent prothrombotic state associated with an unprovoked EHPVO. In patients with an unprovoked EHPVO and no prothrombotic conditions, or in those with a provoked EHPVO, anticoagulant treatment is recommended for a minimum of 3-6 months.

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.

Recommended timing for surveillance ultrasonography to diagnose portal splenic vein thrombosis after laparoscopic splenectomy

BACKGROUND

Symptomatic portal or splenic vein thrombosis (PSVT) is a rare but potentially lethal complication of laparoscopic splenectomy (LS). While routine postoperative duplex ultrasound surveillance can be used for early detection, the optimal timing is unknown. The aim of this study is to investigate the incidence and progression of asymptomatic PSVT 1 week and 1 month after LS.

METHODS

Consecutive patients scheduled for LS for hematologic disease participated in this study. Patients underwent surveillance for PSVT using duplex ultrasonography 1 week and 1 month postoperatively.

RESULTS

43 of 48 patients planning to undergo LS in the study period were enrolled, with 3 subsequently excluded, leaving 40 for further analysis. The indications for LS were benign disease in 31 [19 had immune thrombocytopenia purpura (ITP)] and malignant disease in 9. A hand-assisted technique was used in 12 cases. PSVT was diagnosed in 9/40 patients (22.5%). Seven (77.8%) were diagnosed by 1 week with ultrasound, of whom one had mild symptoms (fever and diarrhea). After anticoagulation, subsequent ultrasounds showed resolution or improvement in all seven patients. Thirty-three patients had a normal ultrasound result at 1 week. One of these patients also had a computed tomography (CT) scan that found a PSVT not seen on ultrasound. Twenty-seven patients returned for follow-up after normal 1-week imaging: 26 patients had an ultrasound at 1 month, with no new PSVT found. One additional patient did not return for subsequent ultrasound until 2 months later, when a new distal SVT was found; ultrasound at 6 months showed complete resolution without treatment.

CONCLUSION

The 1-week incidence of PSVT after LS was 8/40 (20%). The high incidence justifies ultrasonographic screening on postoperative day 7. If asymptomatic PSVT has not developed at this time, it is unlikely to develop by 1 month, and subsequent screening ultrasound at 1 month is not required.

Cytomegalovirus-associated superior mesenteric vein thrombosis treated with systemic and in-situ thrombolysis

A 56-year-old patient, first diagnosed with an acute cytomegalovirus infection, presented with progressive abdominal pain because of a superior mesenteric vein thrombosis for which he was treated with systemic thrombolysis and heparin in continuous infusion. As this therapy did not have the intended success after 5 days, an interventional radiological procedure was performed with local thrombolysis in the superior mesenteric artery resulting in recanalisation of the vein. Oral anticoagulation was initiated and continued for a period of 6 months. Mesenteric venous thrombosis is a relatively uncommon cause of mesenteric ischemia that can be associated with severe morbidity and significant mortality. With noninvasive techniques, it is possible to establish a diagnosis in the majority of the cases. The importance of an early diagnosis and therapy - not only with anticoagulation, but also thrombolysis in selected cases - is shown with this case and review of the literature.

Acute mesenteric ischemia

Acute mesenteric ischemia is caused by a critical reduction in intestinal blood flow that frequently results in bowel necrosis and is associated with a high mortality. Clinicians must maintain a high index of suspicion because a prompt diagnosis and early aggressive treatment before the onset of bowel infarction results in reduced mortality. Medical management includes aggressive rehydration and the use of antibiotics, anticoagulation, vasodilators, and inhibitors of reperfusion injury. If acute mesenteric ischemia is suspected, early angiography is imperative, as it permits accurate diagnosis and possible therapeutic intervention. Therapeutic options during angiography depend on the cause of ischemia and include administering intra-arterial vasodilators and/or thrombolytic agents and angioplasty with or without stent placement. If interventional techniques are not possible or if the patient presents with suspicion of bowel infarction, surgery is warranted. Surgical techniques include superior mesenteric artery embolectomy or visceral artery bypass, which should be used before bowel resection to ensure only resection of nonviable bowel.

Cavernous transformation of portal vein: 16-slice CT portography and correlation with surgical procedure of orthotopic liver transplantation

OBJECTIVE

To evaluate 16-slice CT portography technique and appearances of cavernous transformation of portal vein (CTPV) and the correlation with surgical procedure of orthotopic liver transplantation (OLT).

MATERIAL AND METHODS

Twenty-four patients with CTPV underwent triphase scanning using a 16-slice CT scanner. Twenty-one of the 24 patients were OLT candidates. After plain scan, enhanced CT scan was performed. The parameters were as follows: thickness of 2.5 mm, reconstruction interval of 1.3 mm, flow rate of 3-4 mL/s, contrast agent of 100 mL, delayed time of 20, 50, and 70 s, respectively. Imaging reformation, including MIP, VR, and SSD, were performed by one radiologist. Two radiologists assessed the thrombosis location and degree, collateral vessels, and superior mesenteric vein (SMV) or splenic vein (SV). The details of collateral vessels, thrombosis location were graded and recorded. One score was partial thrombosis of the main PV; 2 score, complete thrombosis of the main PV; 3 score, complete thrombosis of the main PV plus thrombosis of proximal SV or SMV, and the normal diameter of remaining veins; 4 score, complete thrombosis of the main PV plus thrombosis of more than a half of SV or SMV, and thin diameter of remaining veins; 5 score, complete nonvisualization of the main PV, one or both of SV and SMV, and thin diameter of remaining veins. Thirteen patients thereafter underwent OLT. Operation record was reviewed case by case.

RESULTS

All cases obtained MIP images, 16 patients got VR images, and five cases had SSD images. These images can display thrombosis location, degree, and collateral vessels. All patients had hepatopetal collateral vessels. Eleven of the 21 OLT candidates had 1 score, two patients 2 score, four patients 3 score, one patient 4 score, and three patients had 5 score. Fourteen of the 21 candidates were performed end-to-end anastomosis between the donor's and recipient's portal veins, in which 11 patients had 1 score, two patients had 2 score, and two patients 3 score. Both patients with 3 score had normal SV; end-to-end anastomoses were performed between the donor portal vein and recipient SV. Two patients are waiting for donors. OLT was canceled or changed in the six patients with 4 score or 5 score. Correlation coefficient between the score of portal vein and surgical decision was 0.813 (P-value less than 0.001, nonparametric correlation).

CONCLUSIONS

Using 16-slice CT portography can noninvasively diagnose CTPV. The appearances of CTPV on the 16-slice CT portography can provide helpful information for surgeons to make an accurate preoperative decision. MIP is the optimal technique for displaying CTPV.

Abdominal Pain in the Elderly

Elderly patients who have abdominal pain remain one of the most challenging patient populations. Signs and symptoms of serious disease are often nonspecific. Atypical presentations are common in elderly patients. In addition, the higher incidence of serious pathology in this population requires emergency physicians to be vigilant and thorough in their work-up. Vascular catastrophes are more likely to be seen in this population, and a broad differential diagnosis needs to be considered.

THREE-DIMENSIONAL HELICAL COMPUTED TOMOGRAPHIC ANGIOGRAPHY OF THE LIVER IN FIVE DOGS

The objective of this study was to develop a simple, safe, minimally invasive protocol to evaluate the hepatic vasculature. Five purpose-bred Beagle dogs underwent noncontrast-enhanced computed tomographic scan of the entire abdomen. A dynamic, nonincremental computed tomography scan at the level of T11 was then performed using a test bolus of contrast medium to determine time to peak opacification and to aid in the calculation of scan delay. The time to peak arterial enhancement ranged from 2.0 to 7.0 s, with a median of 2.0 s. The time to peak portal venous enhancement ranged from 23.0 to 46.0 s, with a median of 32.0 s. Scan delay for arterial opacification ranged from 0 to 5.0 s, with a median of 0 s. Scan delay for the portal phase of opacification ranged from 6.0 to 21.0 s, with a median of 17.0 s. Using this information, two separate computed tomographic studies were used to image the arterial and portal venous phases of circulatory opacification, respectively. The dogs were hyperventilated to prevent breathing motion during the scan, each of which required approximately 20 s. A power injector was used to inject diatrizoate meglumine (128 mg I/kg) through an 18-gauge cephalic vein catheter at a rate of 5 ml/s. Scanning was initiated after the appropriate scan delay to optimize the specific phase of vascular filling. Maximum intensity projections allowed clear delineation of the hepatic arteries and the portal venous system, while eliminating overlying structures that might interfere with image analysis. Time/density curves were generated, and the time needed for each study was recorded. Hepatic arteries and portal veins were clearly visualized in all dogs. Parenchymal opacification was also observed.

Multidetector Row CT of the Liver

CT has always played a major role in the imaging of the liver despite continuous challenge by ultrasound and MR imaging. Introduction of multidetector row CT technology has helped CT to excel in its already established indications and has expanded its capabilities by adding new clinical indications, such as CT angiography or liver perfusion. This article discusses the advantages of multidetector row CT scanners in liver imaging, examines the guidelines to improve image quality by optimizing scanning protocols and contrast administration strategies, and reviews the current and potential clinical applications.

Review article: portal vein thrombosis -- new insights into aetiology and management

Portal vein thrombosis may occur in the presence or absence of underlying liver disease, and a combination of local and systemic factors are increasingly recognized to be important in its development. Acute and chronic portal vein thrombosis have traditionally been considered separately, although a clear clinical distinction may be difficult. Gastrooesophageal varices are an important complication of portal vein thrombosis, but they follow a different natural history to those with portal hypertension related to cirrhosis. Consensus on optimal treatment continues to be hampered by a lack of randomized trials, but recent studies demonstrate the efficacy of thrombolytic therapy in acute thrombosis, and the apparent safety and benefit of anticoagulation in patients with chronic portal vein thrombosis.

Mesenteric ischemia

MI remains a highly lethal entity. Improving survival requires an aggressive, multidisciplinary approach. High-risk patients with severe abdominal pain and a paucity of physical findings should be undergo emergent imaging in a search for this disease. Improvements in laboratory tests and advances in imaging techniques may improve the ability to diagnose MI earlier in its course, before irreversible damage has occurred. Many treatment modalities are available and should be tailored to each individual case. By recognizing and preventing ischemia-reperfusion injury,the cycle of protracted complications may be broken. A decrease in the mortality from MI finally is occurring. Early recognition and aggressive treatment finally may allow clinicians to have a marked impact on patient survival.

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Imagerie des ischémies intestinales

Ischemic bowel disease includes acute and chronic mesenteric ischemia, and colon ischemia. Cross-sectional imaging, and more particularly computed tomography, has an increasing role in the detection of acute and chronic mesenteric ischemia. Vascular obstructions or stenoses and changes in the bowel wall can be observed. Functional information can be added with MRI by using sequences that are sensitive to oxygen saturation in the superior mesenteric vein. Arteriography remains the reference examination in patients with acute mesenteric ischemia.

Endoscopic ultrasound is a sensitive and specific test to diagnose portal venous system thrombosis (PVST)

OBJECTIVES

Thrombosis of the portal venous system (PVS) may complicate cirrhosis, pancreatitis, malignancies, and hypercoagulable states. Computed tomography (CT) scanning can diagnose thrombi present in the lumen of the PVS, but is probably insensitive. Endoscopic ultrasound (EUS) may be a more sensitive test for diagnosing PVS thrombosis (PVST). We sought to determine the accuracy of EUS for the diagnosis of PVST.

METHODS

Using a retrospective analysis of patients' studies retrieved from a database at Massachusetts General Hospital, we determined the sensitivity and specificity of EUS in 16 patients with PVST and 29 without PVST as proven by surgery and/or CT scanning. All patients underwent a linear EUS exam of the PVS and the results of the EUS report were used as the basis of the study.

RESULTS

The sensitivity of EUS for the finding of PVST was 81% in 13 of 16 patients and the specificity was 93% in 27 of 29 patients with an overall accuracy of 89% (40/45). In an additional group of 11 patients, EUS demonstrated the presence of a PVST that was not detected by CT scanning.

CONCLUSION

Linear EUS is a highly sensitive and specific test for PVST.

Diagnosis and management of intestinal ischaemic disorders

Although intestinal ischaemia is an infrequent event, early recognition and appropriate treatment can reduce the potential for a devastating outcome

Three-dimensional contrast-enhanced MR angiography in diagnosis of portal vein involvement by hepatic tumors

AIM: To assess the accuracy of three-dimensional contrast-enhanced magnetic resonance angiography (3D CE MRA) in evaluation of the portal vein involvement in patients with hepatic tumors.

METHODS: 3D CE MRA was performed in 62 patients with hepatic tumors to assess the patency of the main, right and left portal veins before hepatic surgery. A total of 186 veins were examined for encasement, occlusion and tumor thrombosis. The results of 3D CE MRA diagnosis were then correlated with the surgical-pathological and intra-operative sonographic findings.

RESULTS: 3D CE MRA correctly detected 48 of 49 involved and 135 of 137 noninvolved portal veins with the sensitivity of 98%, specificity of 99%, positive predictive value of 96% and negative predictive value of 99%.

CONCLUSION: 3D CE MRA is accurate in evaluation of the portal vein involvement in patients with hepatic tumors.