CT of acute bowel ischemia

Non‑obstructive mesenteric ischaemia during drug therapy for maxillary cancer: A case report

Non-occlusive mesenteric ischaemia (NOMI) refers to irreversible intestinal ischaemia and necrosis in the absence of organic obstruction to the mesenteric blood vessels. In cases of delayed diagnosis, the prognosis is poor and the mortality rate is 58-70%, being the highest among patients with acute mesenteric ischaemia. The risk factors for this disease include heart disease, sepsis, and administration of catecholamines and digitalis; however, there are few reports of its onset during drug therapy for malignant tumours. The present study reported the case of an 85-year-old man who developed NOMI during drug therapy for maxillary cancer. The patient was diagnosed with right maxillary carcinoma, for which paclitaxel, carboplatin and cetuximab (PCE) therapy was administered. Four days after starting the second course of PCE therapy, the patient visited the emergency department of our hospital with chief complaints of melena and abdominal pain. Contrast-enhanced computed tomography revealed ischaemia from the transverse to the descending colon, leading to a diagnosis of NOMI. Colectomy and colostomy were performed during the emergency surgery on the same day. Although the patient's general condition improved, he was transferred to a recuperation facility for palliative care.

Ultrasound evaluation of portal venous gas and its mimics

Portal venous gas on abdominal ultrasound classically represents an indirect indicator of bowel ischemia, a critical condition which poses a high patient mortality and therefore warrants emergent corrective action. While the classic appearance of portal venous gas on ultrasound is well-described in the literature, the characteristic descriptors are nonspecific and may actually represent other less emergent mimics. Therefore, while radiologists should remain vigilant for the detection of findings corresponding to portal venous gas, they should also be aware of similar-appearing entities in order to provide the most accurate diagnosis. This pictorial essay will open with imaging examples of true portal venous gas attributable to bowel ischemia and describe the classic features which should alert radiologists to this specific diagnosis. Subsequently, this pictorial essay will provide imaging examples of other various other clinical entities which on ultrasound may share similar imaging characteristics. An important objective of this pictorial essay is to highlight distinguishing imaging features along with specific clinical circumstances for each pathological entity which can direct radiologists into identifying the correct diagnosis.

Ultrasonography of acute retroperitoneum

The retroperitoneum is an important space in the human body that is often implicated in a range Epub ahead of print of acute medical conditions, some of which can be life-threatening. Ultrasonography may serve as a pivotal first-line imaging technique when assessing patients with suspected retroperitoneal abnormalities. Effective ultrasonography of the retroperitoneum requires a comprehensive grasp of its anatomy, adjacent structures, and potential pathologies. Being well-acquainted with the imaging characteristics of acute conditions can meaningfully assist in an accurate diagnosis and guide subsequent management. This review article summarizes and illustrates the acute conditions involving the retroperitoneum through the lens of ultrasound imaging.

The Diagnostic Value of Biomarkers in Acute Mesenteric Ischaemia Is Insufficiently Substantiated: A Systematic Review

OBJECTIVE

There is an urgent need for accurate biomarkers to support timely diagnosis of acute mesenteric ischaemia (AMI) and thereby improve clinical outcomes. With this systematic review, the aim was to substantiate the potential diagnostic value of biomarkers for arterial occlusive AMI.

DATA SOURCES

The Pubmed, Embase, and the Cochrane Library electronic databases were searched.

REVIEW METHODS

A systematic review of the literature has been conducted to define the potential diagnostic value of biomarkers for arterial occlusive AMI. All studies including ≥ 10 patients describing biomarkers for macrovascular occlusive AMI between 1950 and 17 February 2023 were identified within the Pubmed, Embase, and the Cochrane Library electronic databases. There were no restrictions to any particular study design, but letters and editorials were excluded. The QUADAS-2 tool was used for the critical appraisal of quality. The study protocol was registered on Prospero (CRD42021254970).

RESULTS

Fifty of 4334 studies were eligible for inclusion in this review. Ninety per cent of studies were of low quality. A total of 60 biomarkers were identified, with 24 in two or more studies and 15 in five or more studies. There was variation in reported units, normal range, and cut off values. Meta-analysis was not possible due to study heterogeneity. Biomarkers currently recommended by the European Journal of Vascular and Endovascular Surgery, European Society for Trauma and Emergency Surgery 2016, and World Society of Emergency Surgery 2017 guidelines also had heterogeneous low quality data for use in the diagnosis of AMI.

CONCLUSION

This systematic review demonstrates high heterogeneity and low quality of the available evidence on biomarkers for arterial occlusive AMI. No clinical conclusions can be drawn on a biomarker or combination of biomarkers for patients suspected of arterial occlusive AMI. Restraint is advised when rejecting or determining AMI solely based on biomarkers.

Advancements in Revascularization Strategies for Acute Mesenteric Ischemia: A Comprehensive Review

Even with modern advancements in the management of acute mesenteric ischemia over the past decade, morbidity and mortality remain high, and the best primary treatment modality is still debated amongst interventionalists. Traditionally, interventionalists have favored an open surgical approach but are now trending for endovascular interventions due to apparent reduced mortality and complications. Newer studies suggest hybrid approaches, and intestinal stroke centers may be superior to either strategy alone. This narrative review will explore the natural history of acute mesenteric ischemia with the aim of increasing interventionalist awareness of modern advancements in revascularization strategies for this devastating disease.

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.

Small bowel transmural necrosis secondary to acute mesenteric ischemia and strangulated obstruction: CT findings of 49 patients

Rationale and objectives

Transmural bowel necrosis (TBN) is an uncommon surgical emergency that represents an endpoint of occlusive acute mesenteric ischemia (AMI), nonocclusive AMI and small bowel obstruction (SBO). According to limited evidence, each etiology of TBN might demonstrate a different CT finding. This investigation aimed to 1) identify overall CT findings of TBN, and 2) compare CT findings of TBN in each etiology.

Materials and methods

Forty-nine consecutive adults (mean age, 64.6 years; 26 men) with occlusive AMI, nonocclusive AMI or SBO, and pathologically proven TBN were enrolled. All had a CT scan within 24 h before surgery. Clinical information was compiled from medical records. CT examinations were re-reviewed by two radiologists with disagreements resolved by the third radiologist. Data were analyzed and compared.

Results

Transmural bowel necrosis were secondary to arterial AMI, venous AMI, combined arterial and venous AMI, nonocclusive AMI, and SBO in 6, 5, 2, 10, and 26 patients, respectively. The CT findings were ascites (93.9%), abnormal wall enhancement (91.8%), bowel dilatation (89.8%), mesenteric fat stranding (89.8%), abnormal wall thickness (71.5%), pneumatosis (46.9%) and intrinsic hyperattenuation of bowel walls (22.5%). Portovenous gas, mesenteric venous gas, and pneumoperitoneum were present in 4 patients (8.2%). Bowel wall thickness was the only CT findings that showed a statistically significant difference among the 5 etiologies of TBN (P = 0.046).

Conclusions

Most common CT findings of TBN were ascites, abnormal bowel wall enhancement, dilatation, and mesenteric fat stranding. Wall thickness differentiated five etiologies, being most thickened in venous AMI and normal in arterial AMI.

Unenhanced CT-based predictive model to identify small bowel necrosis in patients with mechanical small bowel obstruction

OBJECTIVES

To investigate the diagnostic value of unenhanced CT in mechanical small bowel obstruction (SBO) with small bowel necrosis, and to establish a predictive model.

METHODS

From May 2017 to December 2021, the patients with mechanical SBO admitted to our hospital were retrospectively collected. Taking pathology-confirmed small bowel necrosis as the gold standard, the experimental group was composed of patients with small bowel necrosis confirmed by pathology, and the control group was composed of patients with no intestinal necrosis confirmed by surgery or successful conservative treatment with no recurrence of intestinal obstruction during 1-month followed-up.

RESULTS

A total of 182 patients were enrolled in this study, 157 patients underwent surgery, of which 35 patients were accompanied with small bowel necrosis and 122 patients were not (33 patients with ischemic findings at surgery without necrosis). Finally, there were 35 patients in the experimental group and 147 patients in the control group. Multivariable logistic regression showed that increased attenuation of small bowel wall (P = 0.002), diffuse mesenteric haziness (P = 0.010), difference of CT value between mesenteric vessel and aorta (P = 0.025) and U-/C-shaped small bowel loop (P = 0.010) were independent risk factors for the diagnosis of mechanical SBO with small bowel necrosis. Through internal verification, the area under curve (AUC) of the predictive model reached 0.886 (95%CI: 0.824-0.947), and the calibration result was moderate.

CONCLUSION

Multiple features (increased attenuation of small bowel wall; difference of CT values between mesenteric vessel and aorta; diffuse mesenteric haziness; and U-/C-shaped small bowel loop) of unenhanced CT have clinical value in the diagnosis of mechanical SBO with small bowel necrosis. The predictive model based on these four features could achieve satisfactory efficiency.

Radiological predictive factors of transmural intestinal necrosis in acute mesenteric ischemia: systematic review and meta-analysis

OBJECTIVE

Transmural intestinal necrosis (TIN) is related to high mortality in patients with acute mesenteric ischemia (AMI). Radiological predictive factors of TIN in AMI remains controversial. This study aimed to identify the CT-based predictive factors of TIN in AMI.

METHODS

EMBASE and PUBMED were searched for publications predicting TIN using radiological features. Quality Assessment of Diagnostic Accuracy Studies-2 was used to assess the methodological quality of individual studies. Data were presented in terms of diagnostic odds ratio (DOR), sensitivity, specificity, and 95% confidence interval (CI). The random-effects models were used for the meta-analysis.

RESULTS

Eleven studies including 1037 cases with AMI were considered. The meta-analysis showed that bowel wall thinning (DOR = 13.10; 95% CI: 3.71, 46.25), decreased or absent bowel wall enhancement (DOR = 5.77; 95% CI: 2.95, 11.30), bowel dilation (DOR = 3.23; 95% CI: 2.03, 5.15), pneumatosis intestinalis (DOR = 5.78; 95% CI: 2.24, 14.95), porto-mesenteric venous gas (DOR = 5.36; 95% CI: 2.14, 13.40), and arterial occlusive AMI (DOR = 2.66; 95% CI: 1.53, 4.63) were risk factors for predicting TIN. Bowel wall thinning and porto-mesenteric venous gas displayed high specificity to diagnose TIN (98%, 95%, respectively). The subgroup analysis showed that decreased or absent bowel wall enhancement (DOR = 8.23; 95% CI: 4.67, 14.51) and bowel dilation (DOR = 3.14; 95% CI: 1.55, 6.39) were predictors of TIN in venous occlusive AMI, which were not related to TIN in arterial-origin AMI.

CONCLUSIONS

For predicting TIN, there are specific radiological features. The radiological predictors of TIN may differ according to the various causes of AMI. Future primary studies should further evaluate the relationships between radiological signs and TIN based on different etiologies.

KEY POINTS

• Bowel wall thinning, decreased or absent bowel wall enhancement, bowel dilation, pneumatosis intestinalis, porto-mesenteric venous gas, and arterial occlusive AMI were risk factors for predicting TIN. • Decreased or absent bowel wall enhancement and bowel dilation were predictors of TIN in venous occlusive AMI, which were not related to TIN in arterial-origin AMI.

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.

Imaging of Bowel Ischemia: An Update, From the AJR Special Series on Emergency Radiology

Acute mesenteric ischemia is a life-threatening condition that results from abrupt reduction in or cessation of blood flow to the bowel. Characterized by nonspecific abdominal symptoms, mesenteric ischemia is infrequently encountered and commonly misdiagnosed, with potentially catastrophic consequences. Prompt clinical diagnosis and early implementation of therapeutic interventions are critical to improving patient outcomes. Because cross-sectional imaging plays a key role in the diagnosis of mesenteric ischemia, radiologists must be familiar with the varied imaging manifestations of intestinal ischemia. Thus, the objectives of this article are to review the various types and common causes of mesenteric ischemia and to describe its spectrum of multimodality imaging findings, with special attention to novel imaging techniques and emerging diagnoses.

Gastrointestinal Ultrasound in Emergency Setting

Acute bowel diseases are responsible for more than one third of subjects who were referred to the emergency department for acute abdominal pain and gastrointestinal evaluation. Gastrointestinal ultrasound (GIUS) is often employed as the first imaging method, with a good diagnostic accuracy in the setting of acute abdomen, and it can be an optimal diagnostic strategy in young females due to the radiation exposure related to X-ray and computed tomography methods. The physician can examine the gastrointestinal system in the area with the greatest tenderness by ultrasound, thus obtaining more information and data on the pathology than the standard physical examination. In this comprehensive review, we have reported the most relevant indications and advantages to using ultrasound in the investigation of abdominal acute pain.

Epidemiology of Acute Mesenteric Ischemia: A Population-Based Investigation

BACKGROUND

There is a lack of population-based studies on acute mesenteric ischemia (AMI). We have therefore performed a nationwide epidemiological study in Estonia, addressing incidence, demographics, interventions and mortality of AMI.

METHODS

A retrospective population-based review was conducted of all adult cases of AMI accrued from the digital Estonian Health Insurance Fund and Causes of Death Registry for 2016-2020 based on international classification of diseases (ICD-10) diagnostic codes and procedure codes (NOMESCO).

RESULTS

Overall, 577 cases of AMI were identified-an annual incidence of 8.7 per 100,000. The median age was 79 (range 32-104) and 57% were female. Predominating comorbidities included hypertensive disease (81%), atherosclerosis (67%), and atrial fibrillation (52%). The majority of cases (60%) were caused by superior mesenteric artery occlusion (thrombosis 54%, embolism 12%, and unclear 34%). Inferior mesenteric artery occlusion occurred in 7%, non-occlusive mesenteric ischemia in 7%, venous thrombosis in 4%, whereas the type remained unclear in 21% of cases. 40% of patients received intervention (revascularization and/or intestinal resection) and 13% active non-operative treatment. In 21% an exploratory laparotomy or laparoscopy revealed unsalvageable bowel prompting end-of-life care, which was the only management in a further 25% of cases.

CONCLUSIONS

The population-based annual incidence of AMI in Estonia was 8.7 per 100,000 during the study period. The overall hospital mortality and 1 year mortality were 64% and 74%, respectively. In the 53% of patients who received active treatment hospital mortality was 32% and 1 year all-cause mortality was 51%.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT04867499.

Understanding CT imaging findings based on the underlying pathophysiology in patients with small bowel ischemia

Because acute small bowel ischemia has a high mortality rate, it requires rapid intervention to avoid unfavorable outcomes. Computed tomography (CT) examination is important for the diagnosis of bowel ischemia. Acute small bowel ischemia can be the result of small bowel obstruction or mesenteric ischemia, including mesenteric arterial occlusion, mesenteric venous thrombosis, and non-occlusive mesenteric ischemia. The clinical significance of each CT finding is unique and depends on the underlying pathophysiology. This review describes the definition and mechanism(s) of bowel ischemia, reviews CT findings suggesting bowel ischemia, details factors involved in the development of small bowel ischemia, and presents CT findings with respect to the different factors based on the underlying pathophysiology. Such knowledge is needed for accurate treatment decisions.

Portal vein gas combined with pneumatosis intestinalis and emphysematous cystitis: A case report and literature review

BACKGROUND

Portal venous gas (PVG) is a rare clinical condition usually indicative of severe disorders, including necrotizing enterocolitis, bowel ischemia, or bowel wall rupture/infarction. Pneumatosis intestinalis (PI) is a rare illness characterized by an infiltration of gas into the intestinal wall. Emphysematous cystitis (EC) is relatively rare and characterized by intramural and/or intraluminal bladder gas best depicted by cross-sectional imaging. Our study reports a rare case coexistence of PVG presenting with PI and EC.

CASE SUMMARY

An 86-year-old woman was admitted to the emergency room due to the progressive aggravation of pain because of abdominal fullness and distention, complicated with vomiting and stopping defecation for 4 d. The abdominal computed tomography (CT) plain scan indicated intestinal obstruction with ischemia changes, gas in the portal vein, left renal artery, superior mesenteric artery, superior mesenteric vein, some branch vessels, and bladder pneumatosis with air-fluid levels. Emergency surgery was conducted on the patient. Ischemic necrosis was found in the small intestine approximately 110 cm below the Treitz ligament and in the ileocecal junction and ascending colon canals. This included excision of the necrotic small intestine and right colon, fistulation of the proximal small intestine, and distal closure of the transverse colon. Subsequently, the patient displayed postoperative short bowel syndrome but had a good recovery. She received intravenous fluid infusion and enteral nutrition maintenance every other day after discharge from the community hospital.

CONCLUSION

Emergency surgery should be performed when CT shows signs of PVG with PI and EC along with a clinical situation strongly suggestive of bowel ischemia.

Clinical features and management of 20 patients with hepatic portal venous gas

The present study investigated the characteristics, diagnosis, treatment and prognosis of hepatic portal venous gas (HPVG) using the data of 20 patients from the Tongji University School of Medicine Affiliated with Yangpu Hospital (Shanghai, China). The aim of the present study was to optimize the management method and improve the prognosis of patients with HPVG. A total of 20 patients were selected using a CT scan to confirm HPVG. All patients were enrolled and identified via a search engine, which examined all CT radiology reports containing the words pneumatosis and/or portal venous gas/air. Data were collected and analyzed, including sex, age, laboratory evidence, etiologies at admission, therapeutic method and in-hospital mortality. The patients consisted of 14 women (mean age, 79.1 years) and six men (mean age, 67.8 years). The results demonstrated that HPVG indicated a higher inflammatory index. The etiologies of HPVG included abdominal infection, pulmonary infection and hemorrhage, whereas the comorbidities included hypertension, diabetes, coronary disease, cerebrovascular disease and renal insufficiency. The present study determined that intestinal obstruction, acute enteritis and pulmonary infection were the main causes of HPVG. Of the 20 patients enrolled in the present study, four patients received surgery and 16 patients received conservative treatment. The overall in-hospital mortality was 25%. The present study indicated that the causes of HPVG may be closely related to inflammation and blood vessel injury. It was also determined that hemodynamic disorders of the intestinal tract and the combination of different types of infection were important contributors towards patient mortality.

Gastrointestinal Ischemia—Stumbling Stone in COVID-19 Patients

The emergence of the novel SARS-CoV2 virus, proclaimed by the World Health Organization (WHO) as a culpable agent for the pandemic situation, caught the scientific and medical communities off guard. One of the most common complications following pulmonary disease is represented by gastrointestinal (GI) disorders, especially ischemic damage. Inflammation, vasculopathy, immobility, endothelial dysfunction, and a hypercoagulable condition have all been proposed as pathophysiological factors for GI ischemia in these patients. Owing to the COVID-19 effect on a variety of GI conditions, especially ischemic changes, and the high mortality rate, physicians should always keep in mind this complication. They should take a deeper look at clinical and imaging modalities in this cohort of patients so that a proper and time-saving treatment strategy can be applied. Our study aimed to elucidate the thrombogenic mechanism in different GI disorders. Moreover, we analyzed the factors related to necrotic GI changes, by summarizing the already reported data of GI ischemia in COVID-19. To the best of our knowledge, this review is the first to incorporate all GI ischemia cases reported in the literature so far.

CT in non-traumatic acute abdominal emergencies: Comparison of unenhanced acquisitions and single-energy iodine mapping for the characterization of bowel wall enhancement

Objectives

To evaluate the benefit of unenhanced CT and single energy iodine mapping (SIM) to conventional contrast-enhanced CT for bowel wall enhancement characterization in an acute abdomen setting.

Methods

CT images from 45 patients with a suspected acute abdomen who underwent abdominopelvic CT from April 2018 to June 2018 were analyzed retrospectively by two independent radiologists. These patients had been referred by emergency department physicians in a context of acute abdominal pain and had a confirmed etiological diagnosis. Three image sets were evaluated separately (portal phase images alone; portal phase images and unenhanced images, portal phase images, and single energy iodine maps). Diagnostic accuracy and confidence were assessed. Quantitative analysis of bowel wall enhancement was also performed.

Results

The number of correct diagnoses increased by 8% and 12% with unenhanced images and 6% and 13% with SIM for readers 1 and 2, respectively, compared to the portal phase only. There was an improvement in the confidence of the etiological diagnosis with the number of certain diagnoses increasing from 23% to 100%, which was statistically significant for reader 2 and of borderline significance for reader 1 (P = 0.002 and 0.052, respectively) when unenhanced phase and SIM were added. The inter-rater agreement improved when unenhanced and portal phase images were associated, compared to portal phase images alone (kappa = 0.652 [ICC=0.482-0.822] and 0.42 [ICC=0.241-0.607] respectively).

Conclusion

SIM and unenhanced images improve the reproducibility and the diagnostic confidence to diagnose ischemic and inflammatory/infectious bowel wall thickening compared to portal phase images alone.

Summary sentence

The analysis of unenhanced and SIM images in association with portal phase images improves the reproducibility and the radiologist's confidence in the etiological diagnosis of acute non-traumatic bowel wall thickening in adults.

Chemotherapy-induced bowel ischemia: diagnostic imaging overview

Cancer patients need multimodal therapies to treat their disease increasingly. In particular, drug treatment, as chemotherapy, immunotherapy, or various associations between them are commonly used to increase efficacy. However, the use of drugs predisposes a percentage of patients to develop toxicity in multiple organs and systems. Principle chemotherapy drugs mechanism of action is cell replication inhibition, rapidly proliferating cells especially. Immunotherapy is another tumor therapy strategy based on antitumor immunity activation trough agents as CTLA4 inhibitors (ipilimumab) or PD-1/PD-L1 inhibitors as nivolumab. If, on the one hand, all these agents inhibit tumor growth, on the other, they can cause various degrees toxicity in several organs, due to their specific mechanism of action. Particularly interesting are bowel toxicity, which can be clinically heterogeneous (pain, nausea, diarrhea, enterocolitis, pneumocolitis), up to severe consequences, such as ischemia, a rare occurrence. However, this event can occur both in vessels that supply intestine and in submucosa microvessels. We report drug-related intestinal vascular damage main characteristics, showing the radiological aspect of these alterations. Interpretation of imaging in oncologic patients has become progressively more complicated in the context of "target therapy" and thanks to the increasing number and types of therapies provided. Radiologists should know this variety of antiangiogenic treatments and immunotherapy regimens first because they can determine atypical features of tumor response and then also because of their eventual bowel toxicity.

Acute Mesenteric Ischemia

The surgical treatment of occlusive acute mesenteric ischemia (AMI) without revascularization is associated with an 80% overall mortality. Early diagnosis is crucial, and revascularization may reduce overall mortality in AMI by up to 50%. A diagnosis of AMI requires a high index of clinical suspicion and the collaborative effort of emergency department physicians, general and vascular surgeons, and radiologists. This article provides an overview of the etiology, physiology, evaluation, and management of acute mesenteric ischemia.

Dual-energy CT of acute bowel ischemia

Acute bowel ischemia is a condition with high mortality and requires rapid intervention to avoid catastrophic outcomes. Swift and accurate imaging diagnosis is essential because clinical findings are commonly nonspecific. Conventional contrast enhanced CT of the abdomen has been the imaging modality of choice to evaluate suspected acute bowel ischemia. However, subtlety of image findings and lack of non-contrast or arterial phase images can make correct diagnosis challenging. Dual-energy CT provides valuable information toward assessing bowel ischemia. Dual-energy CT exploits the differential X-ray attenuation at two different photon energy levels to characterize the composition of tissues and reveal the presence or absence of faint intravenous iodinated contrast to improve reader confidence in detecting subtle bowel wall enhancement. With the same underlying technique, virtual non-contrast images can help to show non-enhancing hyperdense hemorrhage of the bowel wall in intravenous contrast-enhanced scans without the need to acquire actual non-contrast scans. Dual-energy CT derived low photon energy (keV) virtual monoenergetic images emphasize iodine contrast and provide CT angiography-like images from portal venous phase scans to better evaluate abdominal arterial patency. In Summary, dual-energy CT aids diagnosing acute bowel ischemia in multiple ways, including improving visualization of the bowel wall and mesenteric vasculature, revealing intramural hemorrhage in contrast enhanced scans, or possibly reducing intravenous contrast dose.

Drug-induced bowel complications and toxicities: imaging findings and pearls

The use of diverse types of drugs can result in a variety of acute and chronic complications that affect almost any organ. The bowel is one of the organs impacted by the side effects of medications. Imaging frequently plays a crucial role in the detection and characterization of complications occurring in the bowel. They include pseudomembranous colitis or antibiotic-associated colitis; angioedema induced by angiotensin-converting enzyme inhibitors; nonsteroidal anti-inflammatory drug-induced enteropathy; cocaine toxicity; clozapine-induced hypomobility; and bowel toxicity induced by chemotherapeutic agents. It is imperative that radiologists are fully aware of these complications and toxicities as well as the relevant findings. In this way, proper treatment can be implemented immediately. The treatment will involve discontinuation of a drug or a change in regimen.

Time limit to rescue intestine with viability at risk caused by blood flow disruption in patients presenting with acute abdomen

Purpose

Early management is crucial for acute intestinal blood flow disorders; however, no published study has identified criteria for the time limit for blood flow resumption. This study specifically examines the time factors for avoiding intestinal resection.

Methods

The subjects of this retrospective cohort study were 125 consecutive patients who underwent emergency surgery for a confirmed diagnosis of intestinal strangulation (n = 86), incarceration (n = 27), or volvulus (n = 12), between January 2015 and March 2021. Intestinal resection was performed when intestinal irreversible changes had occurred even after ischemia was relieved surgically. We analyzed the relationship between the time from computed tomography (CT) imaging to the start of surgery (C-S time) and intestinal resection using the Kaplan–Meier method and calculated the estimated intestinal rescue rate. Patient background factors affecting intestinal resection were also examined.

Results

The time limit for achieving 80% intestinal rescue rate was 200 min in C-S time, and when this exceeded 300 min, the intestinal rescue rate dropped to less than 50%. Multivariate analysis identified the APACHE II score as a significant influencing factor.

Conclusion

A rapid transition from early diagnosis to early surgery is critical for patients with acute abdomen originating from intestinal blood flow disorders. The times from presentation at the hospital to surgery should be reduced further, especially for severe cases.

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.

Acute Mesenteric Ischemia in Patients with COVID-19: Review of the literature

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in a global health emergency. In addition to common respiratory symptoms, some patients with COVID-19 infections may experience a range of extra-pulmonary manifestations, such as digestive system involvement. Patients with COVID-19 have been reported to suffer from acute mesenteric ischemia (AMI) that is associated with disease-related severity and mortality. However, in the context of COVID-19, the exact cause of AMI has yet to be clearly defined. This review provides a comprehensive overview of the available data and elucidates the possible underlying mechanisms linking COVID-19 to AMI, in addition to highlighting therapeutic approaches for clinicians. Finally, given the severe global impact of COVID-19, we emphasize the importance of coordinated vaccination programs.

Radiological and clinical findings of idiopathic myointimal hyperplasia of mesenteric veins: Case report

INTRODUCTION

Idiopathic myointimal hyperplasia of mesenteric veins (IMHMV) is an uncommon cause of ischemic bowel disease resulting from the proliferation of smooth muscles in the venous intima. Delayed diagnosis could only be made following the surgical resection due to lack of imaging data, which may lead to bowel severe bleeding, perforation, necrosis, infection, or shock. In previous reports, few cases have provided the detailed pre-operative radiological characteristics of IMHMV. Herein, we are the first to provide the complete clinical course and comprehensive pre-operative radiological data of a 21-year-old female diagnosed with IMHMV.

PATIENT CONCERNS

A 21-year-old female was admitted to our hospital with bloody diarrhea and abdominal pain. Physical examination revealed tenderness localized to the left lower abdomen. The patient had no prior history of similar symptoms. A computed tomography scan was performed and showed diffuse wall thickening from the rectum to sigmoid colon with poor mural enhancement, multiple ulcers, fat stranding, and free fluid. The arterial phase images demonstrated many tortuous pericolic arteries and submucosal pseudoaneurysm.

INTERVENTION

Conservative treatment including empirical antibiotics, Mesalazine, and methylprednisolone sodium succinate were administrated to relief the symptoms. However, the diarrhea and abdominal pain worsened. An emergency surgery was arranged and total proctocolectomy with ileal pouchanal anastomosis with ileostomy was performed.

DIAGNOSIS

Macroscopic and histopathological examinations of the excised specimen showed ischemic colitis. Elastica van Gieson staining revealed extensive myointimal hyperplasia and confirmed the diagnosis of IMHMV.

OUTCOMES

During the 2-year follow-up period, no additional medical management was needed. The patient was well and surveillance colonoscopy showed normal colon and anastomosis.

CONCLUSION

Pre-operative computed tomography with imaging features including pronounced continuous concentric thickening colonic wall with poor enhancement and enlarged tortuous pericolic arteries could specifically facilitate the speedy diagnosis of IMHMV.

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.

Thrombosis in abdominal vessels associated with COVID-19 Infection: A report of three cases

Hypercoagulability related to SARS-CoV-2 infection is one of the main extrapulmonary complications of COVID-19. We present three cases of intrabdominal thrombotic complications related to the state of hypercoagulability of COVID-19 and its tomographic features. Hypercoagulability state should be taking into account in the interpretation of radiological images in all infected patients with COVID-19.

Acute Mesenteric Ischemia: A Challenge for the Acute Care Surgeon

Acute mesenteric ischemia is considered uncommon, but it appears to be more frequent cause of acute abdomen than appendicitis or ruptured abdominal aortic aneurysm in elderly patients. Surgical treatment without revascularization is associated with high overall mortality, up to 80%. The modern treatment of acute mesenteric ischemia requires collaboration of gastrointestinal surgeons, vascular surgeons, and interventional radiologists. Early revascularization may reduce the overall mortality associated with acute mesenteric ischemia by up to 50%. Clinical suspicion and contrast-enhanced computed tomography performed at early stage are keys to improve outcomes of acute mesenteric ischemia treatment. This review summarizes what the acute care surgeon needs to know about acute mesenteric ischemia with special emphasis on slowly progressing "acute on chronic" mesenteric ischemia.

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.

Acute type A aortic dissection with mesenteric malperfusion syndrome: a case report

BACKGROUND

Patients with acute type A aortic dissection and mesenteric malperfusion syndrome (mesMPS) have a high mortality rate. Therefore, the analysis of the timing of open aortic repair and intestinal operation is of great significance for the timely selection of clinical treatment.

CASE SUMMARY

The chief complaints of the patient were sudden chest and back bursting pain for 15 h. Emergency "ascending aorta replacement + total arch replacement (island flap anastomosis) + descending aorta stent implantation + coronary artery bypass grafting + autologous vascular access" was performed. The patient's postoperative occult blood test was positive. His blood stool was visible to the naked eye on the 11^th day after the open aortic repair. He had abdomen tenderness on the 12^th postoperative day. He had abdominal pain and was diagnosed by CT with intestinal obstruction on the 13^th postoperative day. Then, he underwent an emergency laparotomy for right hemicolectomy + partial resection of small intestine + cholecystectomy + ileostomy. He was discharged with diagnoses of aortic dissection (type A), coronary dissection, multiple perforations of the colon, congenital ectopic small bowel glands, and acute attack of chronic cholecystitis. More than a year later, he underwent "intestinal adhesion lysis + ileostomy closure + incisional hernia repair". The patient recovered well at the 1-year follow-up.

CONCLUSION

We have reported a case of acute type A aortic dissection with mesenteric malperfusion syndrome. In the early stage of mesenteric hypoperfusion syndrome, specific laboratory examination indexes and clinical manifestations are lacking, and mesenteric multidetector CT angiography is a first-line examination method for mesenteric malperfusion. Through the detailed analysis of the patient's condition and the review of the relevant literature, we hope to have a deeper understanding of this condition and provide evidence supporting the formulation of clinical treatment plan.

Bowel ultrasonography in acute abdomen: beyond acute appendicitis

Acute abdomen is a common reason for consultation in the emergency department. A broad spectrum of entities, including diverse diseases of the gastrointestinal tract, can cause acute abdomen. Although computed tomography is the technique most widely used to evaluate acute abdomen in the emergency department, abdominal ultrasound is often performed first and allows bowel disease to be suspected. This article describes the ultrasound features of diverse bowel diseases that can cause acute abdomen, such as acute diverticulitis, bowel obstruction, gastrointestinal perforation, bowel ischemia, intraabdominal fat necrosis, and miscellaneous processes such as endometriosis, foreign bodies, or vasculitis. Radiologists must be familiar with the different features of abnormal bowel that can be detected incidentally in patients without clinical suspicion of bowel disease. This article focuses on ultrasonographic signs of bowel disease; other articles in this series cover the ultrasonographic signs of acute appendicitis, inflammatory bowel disease, and infectious diseases.

Cross-Sectional Imaging Evaluation of Vascular Lesions in the Gastrointestinal Tract and Mesentery

Gastrointestinal (GI) tract and mesenteric vascular lesions can have various clinical presentations, of which GI bleeding is the most common. This collection of pathology is highly variable in etiology ranging from occlusive disease to vascular malformations to trauma to neoplasms which makes for a challenging workup and diagnosis. The advent of multiple imaging modalities and endoscopic techniques makes the diagnosis of these lesions more achievable, and familiarity with their various imaging findings can have a significant impact on patient management. In this article, we review the gamut of GI tract and mesenteric vascular lesions and their associated imaging findings.

Gastrointestinal Ultrasound (GIUS) in Intestinal Emergencies - An EFSUMB Position Paper

An interdisciplinary group of European experts summarizes the value of gastrointestinal ultrasound (GIUS) in the management of three time-critical causes of acute abdomen: bowel obstruction, gastrointestinal perforation and acute ischemic bowel disease. Based on an extensive literature review, statements for a targeted diagnostic strategy in these intestinal emergencies are presented. GIUS is best established in case of small bowel obstruction. Metanalyses and prospective studies showed a sensitivity and specificity comparable to that of computed tomography (CT) and superior to plain X-ray. GIUS may save time and radiation exposure and has the advantage of displaying bowel function directly. Gastrointestinal perforation is more challenging for less experienced investigators. Although GIUS in experienced hands has a relatively high sensitivity to establish a correct diagnosis, CT is the most sensitive method in this situation. The spectrum of intestinal ischemia ranges from self-limited ischemic colitis to fatal intestinal infarction. In acute arterial mesenteric ischemia, GIUS may provide information, but prompt CT angiography is the gold standard. On the other end of the spectrum, ischemic colitis shows typical ultrasound features that allow correct diagnosis. GIUS here has a diagnostic performance similar to CT and helps to differentiate mild from severe ischemic colitis.

Extensive hepatic portal venous gas and gastric pneumatosis in a cat

A 15-year-old female neutered Domestic Long Hair cat was presented for acute hematemesis. Initial diagnostic workup, including serum biochemistry panel, complete blood count and coagulation profile, was unremarkable. Abdominal ultrasound showed gastric mural thickening and non-obstructive gastric foreign material. Endoscopy was performed to remove the foreign matter and obtain biopsies. Significant abnormalities of the upper gastrointestinal (GI) tract were not noted endoscopically. Overnight, the patient required a packed red blood cell transfusion following two episodes of severe hematemesis, hypotension and collapse. Serial radiographs and ultrasound revealed hepatic portal venous gas (HPVG). Computed tomography (CT) scan confirmed massive gas accumulation within the liver and emphysematous gastritis. The patient became increasingly unstable and, given her rapid decline, humane euthanasia was elected. Gastric and duodenal histopathology showed inflammatory changes, spirochetosis and mucosal epithelial degeneration. HPVG is a rarely described finding and prognosis varies drastically depending on aetiology. To the best of our knowledge, this is the first description of portal vein gas documented on multiple imaging modalities, including CT, in a cat. The patient in this report had several potential risk factors including prior endoscopy, compromise of the intestinal barrier and evidence of gastric mural bacterial invasion.

Ischemic colitis after enema administration: Incidence, timing, and clinical features

BACKGROUND

Enema administration is a common procedure in the emergency department (ED). However, several published case reports on enema-related ischemic colitis (IC) have raised the concerns regarding the safety of enema agents. Nevertheless, information on its true incidence and characteristics are still lacking.

AIM

To investigate the incidence, timing, and risk factors of IC in patients receiving enema.

METHODS

We consecutively collected the data of all adult patients receiving various enema administrations in the ED from January 2010 to December 2018 and identified patients confirmed with IC following enema. Of 8320 patients receiving glycerin enema, 19 diagnosed of IC were compared with an age-matched control group without IC.

RESULTS

The incidence of IC was 0.23% among 8320 patients receiving glycerin enema; however, there was no occurrence of IC among those who used other enema agents. The mean age ± standard deviation (SD) of patients with glycerin enema-related IC was 70.2 ± 11.7. The mean time interval ± SD from glycerin enema administration to IC occurrence was 5.5 h ± 3.9 h (range 1-15 h). Of the 19 glycerin enema-related IC cases, 15 (79.0%) were diagnosed within 8 h. The independent risk factors for glycerin-related IC were the constipation score [Odds ratio (OR), 2.0; 95% confidence interval (CI): 1.1-3.5, P = 0.017] and leukocytosis (OR, 4.5; 95%CI: 1.4-14.7, P = 0.012).

CONCLUSION

The incidence of glycerin enema-related IC was 0.23% and occurred mostly in the elderly in the early period following enema administration. Glycerin enema-related IC was associated with the constipation score and leukocytosis.

The role of computed tomography in the diagnostic pathway of acute mesenteric ischemia: a nested case-control study

BACKGROUND

Computed tomography (CT) can be used as the primary screening modality for the evaluation of patients suspected of having acute mesenteric ischemia known to show high sensitivity and specificity rates.

PURPOSE

To prove the value of CT in patients with pathological abdominal findings following cardiac surgery.

MATERIAL AND METHODS

In a retrospective case-control study, 12 different CT scan parameters of patients with or without mesenteric ischemia following cardiac surgery were compared using univariate and logistic regression analyses.

RESULTS

Of 14,176 patients, 133 (0.9%) received an abdominal CT scan during postoperative care due to pathological abdominal findings. Sixty-eight patients were diagnosed with acute mesenteric ischemia. In-hospital mortality was 73.5% for this group. CT parameters with the highest specificity for indicating colonic ischemia were intestinal (99%) or porto-venous (96%) pneumatosis, abnormal contrast medium enhancement (89%), and occlusion of the proximal inferior mesenteric artery (81%). All of those parameters showed low sensitivity levels in the range of 15%-23%. A statistically significant association between acute mesenteric ischemia and CT appearance was obtained for contrast medium enhancement (odds ratio [OR] 12.2, 95% confidence interval [CI] 1.5-99.2) and intestinal pneumatosis (OR 21.0, 95% CI 2.7-165.2) only.

CONCLUSION

The typical CT criteria indicating mesenteric ischemia lose their accuracy in patients under critical clinical conditions. As CT remains the first-line diagnostic imaging modality for abnormal abdominal findings following cardiac surgery, negative signs should not prevent early laparotomy if clinical suspicion remains high.

Foramen of Winslow hernia years after a Ladd's procedure: A case report

Foramen of Winslow hernias form 8% of all internal hernias. They present with non-specific findings and are often diagnosed late in disease progression. Delayed diagnosis of the hernia is associated with an estimated mortality of 50%. This rare event has yet to be described in the literature as a follow-up complication to a Ladd's procedure. Here, we present a young male patient with a surgical history of a Ladd's procedure with a chief complaint of an acute-onset, severe abdominal pain accompanied by episodes of emesis. Prompt clinical analysis, imaging and fluid resuscitation was conducted. A computed tomography (CT) scan showed a mesenteroaxial gastric volvulus and air was identified within the Falciform Ligament. Consequently, the patient underwent an exploratory laparotomy and the foramen of Winslow hernia was identified. An excision and anastomosis procedure was performed, and the cecum was fixed in the lower left quadrant. The procedure had no complications and the patient was discharged from the hospital on the fifth post-operative day. The purpose of this case report is to present an unusual patient who experienced a foramen of Winslow hernia involving the small bowel six years following a Ladd's procedure. While a causative relation cannot be made between these two events, we theorize that gastrointestinal hypermobility, being one of the three properties leading to herniation, played a role in both pathologies. Therefore, a vigilant surgeon should keep in mind that intra-abdominal congenital malrotation can put patients at greater risk for future herniation.

Still time to perform intestinal revascularization in patients with acute mesenteric ischemia with peritonitis: An analysis of bowel viability in resections

Objective:

Acute mesenteric ischemia is often fatal, and many survivors develop short bowel syndrome. To avoid massive bowel resection, revascularization is recommended for acute mesenteric ischemia patients. However, whether acute mesenteric ischemia patients with clinical peritonitis can be revascularized remains uncertain. Therefore, this study aimed to evaluate the histopathological potential reversibility of resected bowel in acute mesenteric ischemia patients with peritonitis.

Methods:

We retrospectively reviewed the medical records of acute mesenteric ischemia patients treated at the Kameda Medical Center between January 2001 and March 2015. Pathological evaluation regarding bowel resection was performed. Patients with and without peritonitis were compared. The primary outcome was the proportion of patients with reversible or irreversible ischemia. Patients with reversible and irreversible ischemia were characterized.

Results:

Of 41 patients, 17 underwent laparotomy, 6 endovascular surgery, and 18 palliative care. Among 23 patients receiving curative treatment, 7 had peritonitis and 13 did not. Seven patients of each group received bowel resection, but 85.7% of those with peritonitis had reversible ischemia. We categorized patients with ischemia into reversible and irreversible groups. The median time between symptom onset and diagnosis in the reversible group was >27 h. Systemic inflammatory response syndrome was found in 72.2% and 66.7% of the reversible and irreversible groups, respectively.

Conclusion:

Acute mesenteric ischemia patients with clinical peritoneal signs may have potentially reversible ischemia. As a result, revascularization should be considered, even in the case of peritonitis.

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.

Relationship between anastomotic leakage and CT value of the mesorectum in laparoscopic anterior resection for rectal cancer

OBJECTIVE

This study aims to indicate whether the CT value of the mesorectum could be correlated with the incidence of anastomotic leakage (AL) in laparoscopic surgery for rectal cancer.

METHODS

The study subjects included 173 patients who underwent laparoscopic anterior resection (LAR) for rectal cancer from September 2005 to 2016 in our institution as well as reliable contrast-enhanced CT preoperatively. Univariate and multivariate analyses were performed to determine the correlation between surgical outcomes, including AL and CT value of the mesorectum.

RESULTS

AL was observed in 30 (17.3%) patients. Amongst short-term surgical outcomes, overall complication showed significant correlation with the CT value of the mesorectum (P = 0.003). In addition, AL was the only factor, which significantly correlated with the CT value of the mesorectum (P = 0.017). By plotting receiver operating characteristic curve, -75 HU was the threshold of the CT value of the mesorectum for predicting AL with an area under the curve of 0.772. Categorized into two groups as per the threshold, low group showed significantly higher incidence of AL (OR, 2.738; 95% CI, 1.105-6.788; P = 0.030) as well as whole complications (OR, 4.431; 95%CI, 1.912-10.266; P = 0.001).

CONCLUSION

The CT value of the mesorectum may be a helpful preoperative radiological biomarker to predict AL after LAR for rectal cancer.

Indications for abdominal imaging: When and what to choose?

Imaging has a very important role in evaluating abdominal pathology. A good knowledge of indications is of crucial importance in the management of the patient with abdominal pathology. Ultrasound, which on its own can lead to an accurate diagnosis, plays a pivotal role in the management of abdominal pathology. The use of ultrasound contrast agents has significantly improved ultrasound diagnostic capacities in both hepatic and non-hepatic pathology. The use of computed tomography should be limited due to the potential harmful side effects of ionizing radiation, but it has established roles in evaluating severe abdominal traumatic and non-traumatic emergencies as well as in staging oncologic patients. Magnetic resonance imaging has very limited utility in abdominal emergencies due to difficulty of accessing the scanner and the long duration of the examination compared to computed tomography or ultrasound. However, magnetic resonance imaging has well-established clinical roles particularly for evaluating diffuse or focal hepatic pathology, benign and malignant bile duct pathology, pancreatic tumors, inflammatory bowel disease and rectal tumors. The aims of the following paper are to familiarize the clinician with the indications for imaging in abdominal pathology, to guide the clinician and radiologist in choosing the correct technique for a particular clinical situation, to prevent the overuse of imaging techniques and to prevent misdiagnosis of disease and incorrect therapy resulting from inappropriate imaging.

Imaging has a very important role in evaluating abdominal pathology. A good knowledge of indications is of crucial importance in the management of the patient with abdominal pathology. Ultrasound, which on its own can lead to an accurate diagnosis, plays a pivotal role in the management of abdominal pathology. The use of ultrasound contrast agents has significantly improved ultrasound diagnostic capacities in both hepatic and non-hepatic pathology. The use of computed tomography should be limited due to the potential harmful side effects of ionizing radiation, but it has established roles in evaluating severe abdominal traumatic and non-traumatic emergencies as well as in staging oncologic patients. Magnetic resonance imaging has very limited utility in abdominal emergencies due to difficulty of accessing the scanner and the long duration of the examination compared to computed tomography or ultrasound. However, magnetic resonance imaging has well-established clinical roles particularly for evaluating diffuse or focal hepatic pathology, benign and malignant bile duct pathology, pancreatic tumors, inflammatory bowel disease and rectal tumors. The aims of the following paper are to familiarize the clinician with the indications for imaging in abdominal pathology, to guide the clinician and radiologist in choosing the correct technique for a particular clinical situation, to prevent the overuse of imaging techniques and to prevent misdiagnosis of disease and incorrect therapy resulting from inappropriate imaging.

High-Value Multidetector CT Angiography of the Superior Mesenteric Artery: What Emergency Medicine Physicians and Interventional Radiologists Need to Know

The superior mesenteric artery (SMA) provides vital blood supply to the midgut, and an acute abnormality can rapidly precipitate bowel ischemia and infarction and lead to morbidity and mortality. Vascular diseases that acutely compromise the SMA threaten its tributaries and include occlusion, dissection, aneurysm rupture, pseudoaneurysm, vasculitis, and SMA branch hemorrhage into the bowel. Emergency medicine physicians rely on the radiologist to identify SMA abnormalities, to characterize them, and to detail findings that guide the appropriate triage of these patients. As such, radiologists must be cognizant of the features that influence patient treatment to assist vascular surgeons and interventional radiologists in decision making. Some patients can be treated medically, while clinical and radiographic findings may suggest the need for interventional or surgical repair of the artery. In the latter case, multidetector CT findings aid in determining which of the various surgical and endovascular treatment options is optimal, and both vascular and gastrointestinal sequelae of acute SMA abnormalities contribute to these determinations. The authors review acute life-threatening conditions involving the SMA including acute occlusion, dissection, aneurysm, pseudoaneurysm, and hemorrhage and discuss the vascular and gastrointestinal multidetector CT findings in each of these conditions that help to guide surgical and interventional management. ^©RSNA, 2019.

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.