Multidetector CT angiography in the diagnosis of mesenteric ischemia

Could CT finding of gas in the sole mesenteric artery be a sign of a severe acute ischemia? Presentation of a rare fatal case and a literature review

Contrast-enhanced abdominal CT is the gold standard for the diagnosis of acute mesenteric ischemia (AMI). CT findings include several anomalies like bowel wall thickening, thinning, attenuation, decreased enhancement, dilated fluid-filled loops, pneumatosis, and portal venous gas. A rare case of gas found only in the superior mesenteric artery (SMA) is presented. A contrast-enhanced CT scan was performed in emergency on an 80-year-old man with vague and diffuse abdominal pain, which showed findings of occlusive AMI. Gas was found in the context of the SMA and its branches, but not in the mesenteric and portal veins. The patient underwent emergency surgery but he died the next day in the intensive care unit for complications. The rare CT finding of gas in SMA during an AMI should be considered a radiological sign of irreversible intestinal damage: surgical prompt intervention is needed, even if the mortality rate is high.

[Update: Small bowel diseases in computed tomography and magnetic resonance imaging]

CLINICAL/METHODICAL ISSUE

Radiological procedures play a crucial role in the diagnosis of small bowel disease. Due to a broad and quite nonspecific spectrum of symptoms, clinical evaluation is often difficult, and endoscopic procedures require significant manpower, are time-consuming and expensive. In contrast, radiologic imaging can provide important information about morphologic and functional variations of the small bowel and help to identify various disease entities, such as inflammation, tumors, vascular problems, and obstruction.

STANDARD RADIOLOGICAL METHODS

The most common radiological modalities in small bowel diagnostics include ultrasound (US), computed tomography (CT), magnetic resonance imaging (MRI), and fluoroscopy. Each of these modalities has its own advantages and limitations, and the choice of imaging modality depends on clinical symptoms and suspected diagnosis in addition to availability.

METHODOLOGICAL INNOVATIONS

In recent years, significant progress has been made, especially in cross-sectional imaging modalities, as a result of new and further technical developments.

PERFORMANCE

These range from increasing detail resolution to functional and molecular imaging techniques that go far beyond simple morphology. In addition, information technology (IT) applications, which include artificial intelligence and radiomics, are assuming an increasing role.

ACHIEVEMENTS

Many of the methods mentioned are still in early stages and need to be further developed for daily practice, but some have already found their way into clinical routine.

PRACTICAL RECOMMENDATIONS

The aim of this work is to provide a review of the most important disease entities of the small intestine, including new and innovative diagnostic approaches.

An Update on Acute Mesenteric Ischemia

Acute mesenteric ischemia (AMI) is an uncommon yet highly lethal cause of acute abdomen in the emergency setting. Computed tomography (CT) imaging, in particular a biphasic protocol consisting of angiographic and venous phase scans, is widely used to corroborate non-specific clinical findings when suspicions of AMI are high. Techniques such as low kilovoltage peak scanning, dual energy acquisition, or a combined arterial/enteric phase can improve iodine conspicuity and evaluation of bowel enhancement. Biphasic CT with CT angiography is mandatory to directly assess for the 3 primary etiologies of AMI-arterial, venous, and non-occlusive mesenteric ischemia (NOMI), and the CT angiographic findings may be the first visible in the disease. In addition, numerous non-vascular CT findings have also been reported. Bowel wall thickening, mesenteric stranding, and ascites are common but non-specific findings that correlate poorly with disease severity. Pneumatosis intestinalis and portomesenteric venous gas, while not pathognomonic for ischemia, are highly specific in cases of high clinical suspicion. Bowel wall hypoenhancement is an early and specific sign but requires a protocol optimizing iodine conspicuity to confidently identify. Finally, intraperitoneal free air and solid organ infarcts are also highly specific ancillary findings in AMI. AMI occurs as a complication in 10% of small bowel obstruction (SBO) patients, and understanding imaging findings of ischemia in the context of SBO is necessary to aid in treatment planning and reduce over- and under-diagnosis of strangulation. Familiarity with the imaging features of ischemia by radiologists is vital to establish an early diagnosis before irreversible necrosis occurs.

Treatment of Acute Mesenteric Ischemia: Individual Challenges for Interventional Radiologists and Abdominal Surgeons

Background: Acute mesenteric ischemia (AMI) is a life-threatening condition resulting from occlusion of the mesenteric arterial vessels. AMI requires immediate treatment with revascularization of the occluded vessels. Purpose: to evaluate the technical success, clinical outcomes and survival of patients receiving endovascular treatment for AMI followed by surgery. Material and Methods: A search of our institution’s database for AMI revealed 149 potential patients between 08/2016 and 08/2021, of which 91 were excluded due to incomplete clinical data, insufficient imaging or missing follow-up laparoscopy. The final cohort included 58 consecutive patients [(median age 73.5 years [range: 43−96 years], 55% female), median BMI 26.2 kg/m2 (range:16.0−39.2 kg/m2)]. Periinterventional imaging regarding the cause of AMI (acute-embolic or acute-on-chronic) was evaluated by two radiologists in consensus. The extent of AMI and the degree of technical success was graded according to a modified TICI (Thrombolysis in Cerebral Infarction scale) score (TICI-AMI) classification (0: no perfusion; 1: minimal; 2a < 50% filling; 2b > 50%; 2c: near complete or slow; 3: complete). Lab data and clinical data were collected, including the results of follow-up laparoscopy. Non-parametric statistics were used. Results: All interventions were considered technically successful. The most common causes of AMI were emboli (51.7%) and acute-on-chronic thrombotic occlusions (37.9%). Initial imaging showed a TICI-AMI score of 0, 1 or 2a in 87.9% (n = 51) of patients. Post-therapeutic TICI-AMI scores improved significantly with 87.9% of patients grade 2b and better. Median lactate levels reduced from 2.7 (IQR 2.0−3.7) mg/dL (1−18) to 1.45 (IQR 0.99−1.90). Intestinal ischemia was documented in 79.1% of cases with resection of the infarcted intestinal loops. In total, 22/58 (37.9%) patients died during the first 30 days after intervention and surgery. According to CIRSE criteria, we did not observe any SAE scores of grade 2 or higher. Conclusions: AMI is a serious disease with high lethality within the first 30 days despite optimal treatment. However, interventional revascularization before surgery with resection of the infarcted bowel can save two out of three of critically ill patients.

Acute mesenteric ischemia: updated guidelines of the World Society of Emergency Surgery

Acute mesenteric ischemia (AMI) is a group of diseases characterized by an interruption of the blood supply to varying portions of the intestine, leading to ischemia and secondary inflammatory changes. If untreated, this process may progress to life-threatening intestinal necrosis. The incidence is low, estimated at 0.09-0.2% of all acute surgical admissions, but increases with age. Although the entity is an uncommon cause of abdominal pain, diligence is required because if untreated, mortality remains in the range of 50%. Early diagnosis and timely surgical intervention are the cornerstones of modern treatment to reduce the high mortality associated with this entity. The advent of endovascular approaches in parallel with modern imaging techniques is evolving and provides new treatment options. Lastly, a focused multidisciplinary approach based on early diagnosis and individualized treatment is essential. Thus, we believe that updated guidelines from World Society of Emergency Surgery are warranted, in order to provide the most recent and practical recommendations for diagnosis and treatment of AMI.

Multidetector Computed Tomography Angiography Role in Diagnosing Superior Mesenteric Arteriovenous Fistula with Superior Mesenteric Vein Thrombosis: A Case Report

Introduction

Arteriovenous fistulas (AVF) of the superior mesenteric vasculature are rare vascular abnormalities. It often occurs due to iatrogenic injuries during bowel resection or abdominal traumas. As the patient exhibits a variety of signs and symptoms and can present late, diagnosis may be difficult.Multidetector computed tomography (MDCT) is the most common modality for imaging the small bowel, vessels, and mesentery in patients with mesenteric ischemia.

Case presentation

We present the case of a 25-year-old man who presented with features of acute intestinal obstruction and was operated on in an emergency. Resection of gangrenous small bowel and bowel adhesiolysis with double barrel ileostomy was performed. During exploratory laparotomy, gangrenous bowels were found, but no cause of mesenteric ischemia could be delineated. Finally, on computed tomography angiography (CTA) superior mesenteric arteriovenous fistula (SMAVF) with superior mesenteric vein (SMV) thrombosis was diagnosed. The patient was advised of aggressive anticoagulant therapy.

Conclusion

Computed tomography angiography has become the most reliable diagnostic modality to confirm the diagnosis and guide the best treatment strategy.

How to cite this article

Satyam S, Kose S, Singh S, et al. Multidetector Computed Tomography Angiography Role in Diagnosing Superior Mesenteric Arteriovenous Fistula with Superior Mesenteric Vein Thrombosis: A Case Report. Euroasian J Hepato-Gastroenterol 2022;12(2):98-101.

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.

Chronic Mesenteric Ischemia: Differential Vascularsurgical Therapy and Its Outcome in a Single-Center Observational Study

Aim: The aim of this study was to investigate short-/long-term vascularsurgical patency and the outcome in chronic mesenteric ischemia (CMI) depending on the mesenteric revascularization technique and reflecting real-world data. Methods: This retrospective single-center observational study registered all patients who had undergone open vascularsurgical reconstruction because of CMI at a tertiary German university hospital comparing 1-versus (vs.) 2-vessel as well as antegrade versus retrograde reconstructions. Results: In total, 35 patients were enrolled (mean [± SD] age, 64 ± 13 [range, 45–83] years; sex ratio [m:f], 16:19 [46:54]) over 12 years. Three patients with symptoms of mesenteric ischemia because of rare causes (radiation-induced and median arcuate ligament syndrome) have been excluded. While 51% of patients underwent 1-vessel reconstruction, 49% underwent 2-vessel reconstruction. There was a trend of (i) more perioperative complications in the 2-vessel group (88.2% vs. 55.6%, p = 0.06) and (ii) higher morbidity at 1 year in the 2-vessel versus 1-vessel group (57.1% and 42.9%, respectively; p = 0.466), while the morbidity of the 2-vessel versus 1-vessel group at 5 years (100% vs. 33.3%) was significantly different (p = 0.009). The mortality was greater in the 2-vessel versus 1-vessel group as it was significantly different in the early postoperative period (31.3% vs. 0, p = 0.016) and at 1 year (50% vs. 0, p = 0.005) and 5 years (100% vs. 11%, p = 0.003). Regarding overall survival, the 1-vessel group showed a significant superiority above the 2-vessel group (p = 0.004). Actually, there was no significant difference of early postoperative morbidity comparing the retrograde and antegrade group (p = 0.285) as well as at 1 year and 5 years (p = 0.715 and p = 0.620, respectively). In addition, there was no significantly different postoperative mortality in antegrade versus retrograde group at each time. Specific and general complication rates were 62.9% and 57.1%, respectively, resulting in an overall morbidity of 77.1% (mortality, 20%). Conclusion: The vascular surgeon should be prepared to perform various procedures of mesenteric reconstruction to tailor the operative strategy to the specific needs of the individual patient.

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.

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.

Vascular assessment in small bowel obstruction: can CT predict requirement for surgical intervention?

PURPOSE

Small bowel obstruction (SBO) is a common cause of emergency presentations for abdominal pain and can be complicated by mesenteric ischemia. Computed tomography is currently central to diagnosis and management planning. Currently accepted signs identify secondary effects of the root physiological insult, which is vascular obstruction. We hypothesized that with advancements in CT technology and reconstruction algorithms, we can now more closely interrogate the mesenteric vasculature for obstruction and more accurately predict the need for surgical intervention.

METHODS

We retrospectively audited the charts of all patients presenting with a clinical diagnosis of SBO at a single institution in a 12-month period. Two blinded consultant radiologists were then asked to analyze 3D MIP reconstruction CT scans for vascular obstruction in addition to any currently accepted signs of ischemia. Comparison between vascular cutoff and accepted current signs in the need for surgical intervention and the presence of any signs of ischemia in theater were recorded.

RESULTS

Vascular cutoff had a comparable, with a trend towards superiority, sensitivity and specificity and inter-observer agreement to currently accepted signs of ischemia. The absence of a cut off sign has an excellent negative predictive value for ischemia with only 2 (3.7%) patients demonstrating ischemia at surgery where the vascular cutoff sign was not seen to be present.

CONCLUSION

Interrogating vascular obstruction using 3D MIP reconstructions in small bowel obstruction may be a more sensitive and specific sign for prediction of surgical intervention, possibly occurring earlier in the obstruction pathway.

Chronic mesenteric ischemia: Clinical practice guidelines from the Society for Vascular Surgery

BACKGROUND

Chronic mesenteric ischemia (CMI) results from the inability to achieve adequate postprandial intestinal blood flow, usually from atherosclerotic occlusive disease at the origins of the mesenteric vessels. Patients typically present with postprandial pain, food fear, and weight loss, although they can present with acute mesenteric ischemia and bowel infarction. The diagnosis requires a combination of the appropriate clinical symptoms and significant mesenteric artery occlusive disease, although it is often delayed given the spectrum of gastrointestinal disorders associated with abdominal pain and weight loss. The treatment goals include relieving the presenting symptoms, preventing progression to acute mesenteric ischemia, and improving overall quality of life. These practice guidelines were developed to provide the best possible evidence for the diagnosis and treatment of patients with CMI from atherosclerosis.

METHODS

The Society for Vascular Surgery established a committee composed of vascular surgeons and individuals experienced with evidence-based reviews. The committee focused on six specific areas, including the diagnostic evaluation, indications for treatment, choice of treatment, perioperative evaluation, endovascular/open revascularization, and surveillance/remediation. A formal systematic review was performed by the evidence team to identify the optimal technique for revascularization. Specific practice recommendations were developed using the Grading of Recommendations Assessment, Development, and Evaluation system based on review of literature, the strength of the data, and consensus.

RESULTS

Patients with symptoms consistent with CMI should undergo an expedited workup, including a computed tomography arteriogram, to exclude other potential causes. The diagnosis is supported by significant arterial occlusive disease in the mesenteric vessels, particularly the superior mesenteric artery. Treatment requires revascularization with the primary target being the superior mesenteric artery. Endovascular revascularization with a balloon-expandable covered intraluminal stent is the recommended initial treatment with open repair reserved for select younger patients and those who are not endovascular candidates. Long-term follow-up and surveillance are recommended after revascularization and for asymptomatic patients with severe mesenteric occlusive disease. Patient with recurrent symptoms after revascularization owing to recurrent stenoses should be treated with an endovascular-first approach, similar to the de novo lesion.

CONCLUSIONS

These practice guidelines were developed based on the best available evidence. They should help to optimize the care of patients with CMI. Multiple areas for future research were identified.

A Novel Approach for Repairing Superior Mesenteric Artery Injury During Left Nephrectomy-6-year Follow-up

OBJECTIVE

To describe a novel approach for reconstructing the superior mesenteric artery (SMA) during left nephrectomy and review the literature.

MATERIALS AND METHODS

The patient was a 57-year-old man with left back pain from an unknown cause for more than 3 hours. A computed tomography scan showed a 12- × 15-cm firm mass and a subcapsular hematoma in the left kidney. It was considered to be bleeding and rupture of the solid renal mass, and because of persistent pain and no documented distant metastatic disease, a transperitoneal laparoscopic nephrectomy was elected, but the procedure was converted to open surgery for SMA injury. We reconstructed the SMA with end-to-end anastomosis between the SMA and the left renal artery stump.

RESULTS

At the 6-year follow-up, the patient had no intestine-related sequelae.

CONCLUSION

Our novel approach of an end-to-end anastomosis between the SMA and the left renal artery stump is an option for SMA injury, especially when orthotopic anastomosis or repair of the SMA is not indicated.

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.

Split-bolus CTA for mesenteric ischemia with a single scan opacifying arterial and mesenteric venous systems

OBJECTIVE

To evaluate the diagnostic accuracy of split-bolus single-scan computed tomography angiography (CTA) protocol for evaluation of acute mesenteric ischemia and alternate diagnoses.

MATERIALS AND METHODS

In this IRB-approved, HIPAA-compliant retrospective study, consecutive patients from 21 October 2016 to 6 May 2018 evaluated for mesenteric ischemia with split-bolus CTA (a single scan in concurrent arterial and portal venous phase) in a single tertiary academic institution were included. Intravenous contrast was administered on weight-based basis. Quantitative and qualitative assessments of superior mesenteric artery (SMA) and superior mesenteric vein (SMV) attenuation and patency were performed by two independent reviewers. CT imaging findings were correlated with clinical reference outcomes.

RESULTS

One hundred fifty-four patients (age 66.3 ± 14.1 years, BMI 27.3 ± 6, 86 (56%) female) were included. CTA studies were performed with a volumetric CT dose index of 15.9 ± 5.5 mSv and dose length product of 1042.9 ± 389.4 mGy cm. Average intravenous contrast volume administered was 164.3 ± 12.1 cc. SMA attenuation was 263.6 ± 92.4HU, SMV was 190 ± 50.2HU. Qualitative assessment of SMA and SMV showed good opacification in all patients. 17/154 (11%) patients were diagnosed on CT with mesenteric ischemia; in 6/154 (4%), CTA studies were indeterminate; in 131/154 (85%), CTA confidently ruled out mesenteric ischemia. Alternate diagnoses were made in 38/154 (25%) patients. Using composite clinical outcomes as a reference standard, sensitivity of split-bolus CTA protocol for diagnosis of mesenteric ischemia is 100% (95% CI 79-100%), and specificity is 99% (95% CI 96-100%).

CONCLUSIONS

Split-bolus CTA has high sensitivity and specificity for diagnosis of acute mesenteric ischemia.

KEY POINTS

• Split-bolus CTA protocol for mesenteric ischemia has great diagnostic accuracy with lower radiation exposure and fewer images to interpret compared with standard multiphasic CTA.

Mesenteric ischemia: what the radiologist needs to know

Acute mesenteric ischemia (AMI) is a life-threatening condition that often presents with abdominal pain. Early diagnosis with contrast-enhanced computed tomography and revascularization can reduce the overall mortality in AMI. This article reviews practical etiological classification, pathophysiology of imaging manifestations and common pitfalls in intestinal ischemia.

The value of CT findings for prognostic prediction of spontaneous superior mesenteric artery dissection

BACKGROUND

Spontaneous superior mesenteric artery (SMA) dissection is rare cause of acute abdomen. Time-dependent change of SMA dissection has not been established.

PURPOSE

To determine Sakamoto classification (SC) type of acute and chronic SMA dissection (aSMAD and cSMAD) to predict the treatment methods and outcome.

MATERIAL AND METHODS

From April 2003 to March 2017, unenhanced and contrast-enhanced CT were used to diagnose acute symptomatic or chronic asymptomatic SMA dissection in 25 consecutive patients without aortic dissection. Correlations between SCs and treatment methods and outcomes were investigated.

RESULTS

All 13 patients with aSMAD initially received conservative treatment. Initial SCs in aSMAD were type I = 1, type III = 9, and type IV = 3. Three of nine initial type III and two of three initial type IV changed to type I at follow-up. One of nine type III changed to type II at follow-up. Ohers did not change. One with initial type III required vascular repair, so the final SC was not available. Three patients required bowel resection. In cSMAD of 12 patients, the initial/final SC were type I and IV in ten and two patients, respectively, without change during follow-up. cSMAD was significantly older than aSMAD. The initial length of dissection of aSMAD was longer than in the cSMAD group. In aSMAD, the final length of dissection was significantly shorter than in the initial computed tomography scan.

CONCLUSION

Initial SC differed significantly between aSMAD and cSMAD. Initial SC types in aSMAD were type III and IV mainly, and changed during the observation period. In cSMAD, SC types were I and IV without change.

Linezolid-Induced Lactic Acidosis Sets Stage for Surgery to Rule Out Mesenteric Ischemia: A Case Report

An 81-year-old woman with extensive peripheral vascular and coronary artery disease was admitted to the intensive care unit with a deep heel abscess and urinary tract infection. When cultures from the heel ulcer yielded vancomycin-resistant enterococci, she was started on the antibiotic linezolid. After several days of intravenous linezolid therapy, she developed severe lactic acidosis (pH 6.89) and elevation of pancreatic enzymes. An emergent exploratory laparotomy was performed to rule out mesenteric ischemia. Findings from the laparotomy were negative, and after elimination of other differential diagnoses, the metabolic acidosis was ultimately attributed to linezolid. Acidosis resolved after discontinuation of linezolid.

Split-bolus single scan CTA for evaluation of mesenteric ischemia

PURPOSE

To evaluate split-bolus single scan CTA protocol for evaluation of acute mesenteric ischemia.

MATERIALS AND METHODS

In this HIPAA-compliant IRB-approved study, consecutive patients evaluated for mesenteric ischemia between 11/2015 and 10/2016 were included. Patients scanned prior to 4/2016 were scanned with multiphasic CTA protocol and after with split-bolus single scan CTA. Objective and subjective evaluation was performed by three board-certified readers. Findings were correlated to composite clinical reference outcome.

RESULTS

Eighty patients were included: 40 with split-bolus and 40 with multiphasic CTA protocol with similar age (60.3 ± 16.2 years vs. 64.7 ± 17.0 years, p = 0.19) and BMI (28.0 ± 6.7 vs. 27.0 ± 8.7, p = 0.56). SMA attenuation was higher in multiphasic protocol compared to split-bolus protocol (336.5 ± 97.5 HU vs. 258.0 ± 67.3 HU, p < 0.001) with similar SMV attenuation (multiphasic 213.7 ± 58.4 HU vs. split-bolus 194.2 ± 52.2 HU, p = 0.14). Optimal phase of bowel, liver, and spleen enhancement was seen in similar high proportion (94-99%) in both protocols. There were 8/40 (20%) positive cases of mesenteric ischemia in each group. There was no difference in the diagnostic confidence of the readers for evaluation of the mesenteric vessels and bowel ischemia. There were no missed cases of mesenteric ischemia in either group. Mean effective dose was 42% lower in the split-bolus group, p < 0.001. There was a higher number of axial images to review in multiphasic protocol compared to split-bolus protocol (437.9 ± 48.7 vs. 263.5 ± 31.2, p < 0.001).

CONCLUSIONS

The split-bolus protocol for evaluation of mesenteric ischemia is clinically feasible with confident and accurate diagnostic ability, while reducing number of images and decreasing radiation exposure to the patient.

Acute mesenteric ischemia: guidelines of the World Society of Emergency Surgery

Acute mesenteric ischemia (AMI) is typically defined as a group of diseases characterized by an interruption of the blood supply to varying portions of the small intestine, leading to ischemia and secondary inflammatory changes. If untreated, this process will eventuate in life threatening intestinal necrosis. The incidence is low, estimated at 0.09–0.2% of all acute surgical admissions. Therefore, although the entity is an uncommon cause of abdominal pain, diligence is always required because if untreated, mortality has consistently been reported in the range of 50%. Early diagnosis and timely surgical intervention are the cornerstones of modern treatment and are essential to reduce the high mortality associated with this entity. The advent of endovascular approaches in parallel with modern imaging techniques may provide new options. Thus, we believe that a current position paper from World Society of Emergency Surgery (WSES) is warranted, in order to put forth the most recent and practical recommendations for diagnosis and treatment of AMI. This review will address the concepts of AMI with the aim of focusing on specific areas where early diagnosis and management hold the strongest potential for improving outcomes in this disease process.

Some of the key points include the prompt use of CT angiography to establish the diagnosis, evaluation of the potential for revascularization to re-establish blood flow to ischemic bowel, resection of necrotic intestine, and use of damage control techniques when appropriate to allow for re-assessment of bowel viability prior to definitive anastomosis and abdominal closure.

Fatal Acute Hemorrhagic Bowel Infarction Caused by Mesenteric Venous Thrombosis

Acute mesenteric venous thrombosis (MVT) is a rare, but life-threatening medical phenomenon. MVT is normally characterized by insidious onset, with nonspecific signs and symptoms. A high index of clinical suspicion is required for diagnosis, and emergency surgery is necessary to optimize the chances of patient survival, especially in the people aged more than 70 years. Surprisingly, based on my review of the literature, no fatal acute MVT case has been reported in the forensic literature. All reported such cases have been documented in medical literature, and most of them have been associated with underlying risk factors for venous thrombosis, such as hypercoagulable state, certain cancers, and stasis of the blood flow. Here, I report the case of a sudden unexpected death due to extensive intestinal ischemia and infarction with massive abdominal hemorrhage caused by acute MVT in a 72-year-old man without known underlying risk factors.

CT angiography in the setting of suspected acute mesenteric ischemia: prevalence of ischemic and alternative diagnoses

PURPOSE

The purpose of the study was to determine the prevalence of ischemic and alternative diagnoses and the diagnostic accuracy of CT angiography (CTA) in the setting of suspected acute mesenteric ischemia (AMI).

MATERIAL AND METHODS

We included 959 patients undergoing CTA for the evaluation of suspected AMI. The final clinical diagnosis was used to determine the prevalence of ischemic and alternative diagnoses and to calculate the diagnostic accuracy of CTA. Prevalence of diagnoses by age, sex, and admission status was compared using Cochran-Armitage and χ ² tests.

RESULTS

Prevalence was 18.8% (180/959) for AMI and 61.2% (587/959) for specific alternative diagnoses. In the remaining 20.0% (192/959), no clear clinical diagnosis was established. The most frequent alternative diagnoses were small-bowel obstruction (10.4%; 61/587), infectious colitis (8.7%; 51/587), pneumonia (6.5%; 38/587), cholecystitis (6.1%; 36/587), and diverticulitis (5.6%; 33/587). Prevalence of specific alternative diagnoses varied significantly according to both age (p < .013) and admissions status (p < 0.001). CTA had a sensitivity and specificity for diagnosing AMI of 89.4%/99.5% and for alternative diagnoses of 86.7%/96.9%, respectively.

CONCLUSION

In the setting of suspected AMI, the prevalence of ischemic and alternative diagnoses varies significantly by age, sex, and admission status. CTA provides for rapid and non-invasive assessment of ischemic and alternative diagnoses with high diagnostic accuracy.

Anatomic and radiologic review of chronic mesenteric ischemia and its treatment

Chronic mesenteric ischemia (CMI) is a vascular occlusive disease process that generally affects the elderly population. Clinical presentation occurs when two of the three mesenteric arteries are affected and includes non-specific abdominal pain and weight loss. The most common cause of CMI is atherosclerotic arterial occlusion. The aim of this review is to present the vascular anatomy of the mesenteric arterial circulation including the different collateral pathways. The imaging findings and the different treatment options with a brief review of the literature is presented.

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.

Evaluating Patients with Left Upper Quadrant Pain

Imaging plays a major role in the evaluation of patients who present to the emergency department with acute left upper quadrant (LUQ) pain. Multidetector computed tomography is currently the primary modality used for imaging these patients. The peritoneal reflections, subperitoneal compartment, and peritoneal spaces of the LUQ are key anatomic features in understanding the imaging appearance of acute diseases in this area. Diseases of the stomach, spleen, pancreas, and splenic flexure are encountered in patients with acute LUQ pain. Optimization of the imaging protocol is vital for accurate diagnosis and characterization of these diseases in the acute setting.

Multidetector CT in emergency radiology: acute and generalized non-traumatic abdominal pain

Multidetector CT (MDCT) is an imaging technique that provides otherwise unobtainable information in the diagnostic work-up of patients presenting with acute abdominal pain. A correct working diagnosis depends essentially on understanding the individual patient's clinical data and laboratory findings. In haemodynamically stable patients with acute severe and generalized abdominal pain, MDCT is now the preferred imaging test and gives invaluable diagnostic information, also in unstable patients after stabilization. In this descriptive review, we focus our attention on acute, severe and generalized or undifferentiated non-traumatic abdominal pain. The main differential diagnoses are acute pancreatitis, gastrointestinal perforation, ruptured abdominal aneurysm and acute mesenteric ischaemia. We will provide radiologist readers with a technical guide to optimize MDCT imaging protocols and list the major CT signs essential to reach a correct diagnosis and guide the best treatment.

Neutrophil-to-lymphocyte ratio as a diagnostic biomarker for the diagnosis of acute mesenteric ischemia

PURPOSE

Due to the diagnostic challenges and dreadful consequences of delayed treatment of acute mesenteric ischemia (AMI), a variety of diagnostic markers have been previously studied. However, the diagnostic value of neutrophil-to-lymphocyte ratio (NLR), which has been suggested to be a predictor of inflammation, has never been studied for AMI.

METHODS

The data of 70 patients who underwent laparotomy (n = 8) and/or bowel resection (n = 62) for AMI (n = 70) between January 2009 and March 2014 were retrospectively analyzed. To investigate the studied parameters' role in the differential diagnosis of AMI, control groups were selected from most common reasons of inflammation-related emergent surgery, acute appendicitis (AA, n = 62) and normal appendix (NA, n = 61). White blood cell (WBC), red cell distribution width (RDW), NLR and mean platelet volume (MPV) values were recorded. Outcome variables of the study were defined as diagnostic and prognostic role of NLR in AMI.

RESULTS

RDW and NLR values were found to be higher in the AMI group than the AA group (p < 0.001 and p < 0.001). Also, WBC and MPV values were higher in the AMI group than the NA group (p = 0.001 and p < 0.001). Combined sensitivity, specificity, positive predictive value and negative predictive value of RDW and NLR for recommended cut-off values were 69.4, 71.2, 57.8 and 80.4 %, respectively.

CONCLUSION

High NLR value (>9.9) seems to be a valuable diagnostic marker of acute mesenteric ischemia. Combined use of NLR, RDW and other clinical assessment, could help the diagnosis of AMI, especially in the absence of advanced imaging modalities and expert radiologic interpretation.

Ischemic colitis: spectrum of CT findings, sites of involvement and severity

To summarize the frequency of findings on IV contrast, enhanced computer tomography (CT) in 335 patients with pathologically proven ischemic colitis (IC) determine the most frequent locations and patterns of involvement and establish the correlation of these findings with the severity of IC. 231 patients were excluded for not having a concomitant CT or for having underlying comorbidities. 104 cases were analyzed. Scans were evaluated for abnormal wall enhancement (AE), bowel wall thickening (BWT), bowel dilatation (DIL), mesenteric fat stranding (FS), venous engorgement (VE), pericolonic free fluid (FF), and pneumatosis (PN) and portomesenteric venous gas. Segmental versus pancolonic involvement was noted. Severity was determined by histopathology criteria. Data obtained are as follows: female to male incidence, 69 % (70) vs. 31 % (34); average age, 64.5; and positive CT, 102/104 (98.1 %). The most frequent findings include FS (88 %), BWT (88 %), and AE (82 %) regardless of severity of involvement. Statistically significant increased risk ratio and likelihood of severe ischemia for PN, DIL, and FF individually. BWT, DIL, FS, FF, VE, and PN together have a probability for severe IC of 91.8 %. A correlation between fewer findings and milder IC was found (R (2) = 0.6771). The most frequently involved segments: descending (64 %) and sigmoid colon (54 %). Splenic flexure (SF) was infrequently involved (n = 8, 7.84 %). Females had two times higher incidence of IC. The most frequent CT findings in IC are FS, BWT, and AE regardless of the severity. PN is suggestive of severe IC. Segmental involvement is the predominant pattern. The distal colon is more frequently involved. SF contrary to the conventional literature is not disproportionately involved in IC.

Computed tomography angiography and magnetic resonance angiography imaging of the mesenteric vasculature

Computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are highly accurate cross-sectional vascular imaging modalities that have almost completely replaced diagnostic catheter angiography for the evaluation of the mesenteric vasculature. CTA is the technique of choice when evaluating patients with suspected mesenteric ischemia; it permits to differentiate between occlusive and nonocclusive etiologies, to evaluate indirect signs of bowel ischemia, and in some instances, to provide alternative diagnoses. MRA has the advantage of not using ionizing radiation and iodinated contrast agents and can be appropriate in the nonacute setting. Both CTA and MRA are suitable for the assessment of patients with suspected chronic mesenteric ischemia, allowing to evaluate the degree of atherosclerotic steno-occlusive disease and the existence of collateral circulation, as well as other nonatherosclerotic vascular pathologies such as fibromuscular dysplasia and median arcuate ligament syndrome. CTA provides excellent depiction of visceral aneurysms and has an important role to plan therapy for both occlusive and aneurysmal diseases and in the follow-up of patients after open or endovascular mesenteric revascularization procedures. This article provides an introduction to the CTA and MRA imaging protocol to study the mesenteric vasculature, the imaging findings in patients presenting with acute and chronic mesenteric ischemia and visceral aneurysms, and the value of these imaging techniques for therapy planning and follow-up.

Multidetector computed tomography of mesenteric ischaemia

Mesenteric ischaemia comprises a broad, heterogeneous group of diseases characterised by inadequate blood supply to the small or large bowel. Acute mesenteric ischaemia is a surgical emergency, with significant associated morbidity and mortality. Because the clinical presentation of mesenteric ischaemia is variable and often nonspecific, a high index of clinical and radiologic suspicion is required for early diagnosis. The severity of mesenteric ischaemia ranges from transient, localised ischaemia to frank necrosis of the bowel. The most common causes of acute mesenteric ischaemia are embolic and thrombotic occlusion of the superior mesenteric artery, whereas chronic mesenteric ischaemia is almost always associated with generalised atherosclerotic disease. Multidetector computed tomography (MDCT) angiography is the preferred imaging test for acute and chronic mesenteric ischaemia. MDCT is useful in making a prompt, more precise diagnosis of mesenteric ischaemia, as well as identifying the cause and potential complications, which are key to reducing patient morbidity and mortality. In this article, we review the clinical features and aetiologies of mesenteric ischaemia and illustrate the imaging manifestations on MDCT.

• Acute and chronic mesenteric ischaemia are morbid conditions challenging to diagnose.

• MDCT is the first-line imaging test for evaluating patients with suspected mesenteric ischaemia.

• Bowel findings include wall thickening, abnormal enhancement, pneumatosis and luminal dilation.

• Vascular occlusion, portomesenteric venous gas, mesenteric congestion and free air can be seen.

The diagnosis of acute mesenteric ischemia: A systematic review and meta-analysis

OBJECTIVES

Acute mesenteric ischemia is an infrequent cause of abdominal pain in emergency department (ED) patients; however, mortality for this condition is high. Rapid diagnosis and surgery are key to survival, but presenting signs are often vague or variable, and there is no pathognomonic laboratory screening test. A systematic review and meta-analysis of the available literature was performed to determine diagnostic test characteristics of patient symptoms, objective signs, laboratory studies, and diagnostic modalities to help rule in or out the diagnosis of acute mesenteric ischemia in the ED.

METHODS

In concordance with published guidelines for systematic reviews, the medical literature was searched for relevant articles. The Quality Assessment Tool for Diagnostic Accuracy Studies-2 (QUADAS-2) for systematic reviews was used to evaluate the overall quality of the trials included. Summary estimates of diagnostic accuracy were computed by using a random-effects model to combine studies. Those studies without data to fully complete a two-by-two table were not included in the meta-analysis portion of the project.

RESULTS

The literature search identified 1,149 potentially relevant studies, of which 23 were included in the final analysis. The quality of the diagnostic studies was highly variable. A total of 1,970 patients were included in the combined population of all included studies. The prevalence of acute mesenteric ischemia ranged from 8% to 60%. There was a pooled sensitivity for l-lactate of 86% (95% confidence interval [CI] = 73% to 94%) and a pooled specificity of 44% (95% CI = 32% to 55%). There was a pooled sensitivity for D-dimer of 96% (95% CI = 89% to 99%) and a pooled specificity of 40% (95% CI = 33% to 47%). For computed tomography (CT), we found a pooled sensitivity of 94% (95% CI = 90% to 97%) and specificity of 95% (95% CI = 93% to 97%). The positive likelihood ratio (+LR) for a positive CT was 17.5 (95% CI = 5.99 to 51.29), and the negative likelihood ratio (-LR) was 0.09 (95% CI = 0.05 to 0.17). The pooled operative mortality rate for mesenteric ischemia was 47% (95% CI = 40% to 54%). Given these findings, the test threshold of 2.1% (below this pretest probability, do not test further) and a treatment threshold of 74% (above this pretest probability, proceed to surgical management) were calculated.

CONCLUSIONS

The quality of the overall literature base for mesenteric ischemia is varied. Signs, symptoms, and laboratory testing are insufficiently diagnostic for the condition. Only CT angiography had adequate accuracy to establish the diagnosis of acute mesenteric ischemia in lieu of laparotomy.

ACR Appropriateness Criteria ® imaging of mesenteric ischemia

Mesenteric ischemia is a rare disease associated with high morbidity and mortality. Acute mesenteric ischemia is most commonly secondary to embolism followed by arterial thrombosis, nonocclusive ischemia, and less commonly venous thrombosis. Chronic mesenteric ischemia is almost always caused by atherosclerotic disease, with rare causes including fibromuscular dysplasia and vasculitis. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment. Patients with mesenteric ischemia usually present with nonspecific abdominal symptoms and laboratory findings. This document evaluates and rates the appropriateness of imaging to evaluate patients with clinically suspected mesenteric ischemia. While catheter-based angiography has been considered the reference standard and enables diagnosis and treatment, advances in computed tomography have made it a first-line test in many patients because it is a fast, widely available, and noninvasive study. Abdominal radiographs and ultrasound have a limited role in diagnosing mesenteric ischemia but are commonly the first ordered tests in patients with abdominal pain and may diagnose more common pathologies.

Ischemic bowel: uncommon imaging findings in a case of cocaine enteropathy

While the clinical findings of cocaine-induced enteropathy from mesenteric ischemia are fairly well understood, there is a paucity of imaging description and detail in the literature that describes these findings. Imaging characteristics of cocaine-induced mesenteric ischemia on CT examination include bowel edema, mucosal enhancement, venous engorgement, mesenteric free fluid, and dilatation of the small bowel lumen. A thorough history, physical examination, and laboratory testing are critical for the diagnosis and prompt surgical intervention may be necessary. We present a case of cocaine-induced mesenteric ischemia in a 49 year old male which resolved within 24 hours of supportive therapy.

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

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