Acute mesenteric ischemia: A critical role for the radiologist

CT evaluation of bowel wall enhancement in pneumatosis intestinalis: preventing non-therapeutic laparotomies

PURPOSE

To evaluate the diagnostic performance of bowel wall enhancement for diagnosing concomitant bowel ischemia in patients with parietal pneumatosis (PI) diagnosed at abdominal CT.

MATERIALS AND METHODS

From January 1, 2012 to December 31, 2021, 226 consecutive patients who presented with PI on abdominal CT from any bowel segment were included. Variables at the time of the CT were retrospectively extracted from medical charts. CT examinations were blindly analyzed by two independent radiologists. The third reader classified all disagreement of bowel enhancement in three categories: (1) normal bowel enhancement; (2) doubtful bowel wall enhancement; (3) absent bowel wall enhancement. Multivariable logistic regression analysis was performed. Concomitant bowel ischemia was defined as requirement of bowel resection specifically due to ischemic lesion in operated patients and death from bowel ischemia in non-operated patients.

RESULTS

Overall, 78/226 (35%) patients had PI associated with concomitant bowel ischemia. At multivariate analysis, Only absence or doubtful bowel wall enhancement was associated with concomitant bowel ischemia (OR = 167.73 95%CI [23.39-4349.81], P < 0,001) and acute mesenteric ischemia associated with PP (OR = 67.94; 95%CI [5.18-3262.36], P < 0.009). Among the 82 patients who underwent a laparotomy for suspected bowel ischemia, rate of non-therapeutic laparotomy increased from 15/59 (25%), 2/6 (50%) and 16/17 (94%) when bowel wall enhancement was absent, doubtful and normal respectively.

CONCLUSION

Absence of enhancement of the bowel wall is the primary feature associated with concomitant bowel ischemia. It should be carefully assessed when PI is detected to avoid non-therapeutic laparotomy.

Probabilistic Prediction of Gastrointestinal Ischemia after Cardiothoracic Surgery

BACKGROUND

 Gastrointestinal ischemia (GIisch) is challenging to diagnose in patients after cardiothoracic surgery. Computed tomography angiography (CTA) carries substantial false-negative and false-positive rates. The aim of the study was to evaluate if a combination of readily available variables improves the diagnosis of GIisch after cardiothoracic surgery.

METHODS

 This retrospective study included patients receiving intensive care after cardiothoracic surgery. GIisch was confirmed by surgical and/or endoscopic findings. A GIisch prediction score was developed using the Spiegelhalter-Knill-Jones system in a training cohort then tested in a validation cohort (patients without obvious signs of GIisch on CTA).

RESULTS

 The training cohort comprised 125 consecutive patients with suspected GIisch in 2008 to 2019, including 85 with confirmed GIisch. CTA, performed in 92 patients, had a high false-negative rate of 17/60 (28%) and a lower false-positive rate of 7/32 (22%). The score included cardiopulmonary bypass, negatively associated with GIisch, and six variables positively associated with GIisch: intraoperative mean arterial pressure < 50 mm Hg, aspartate aminotransferase > 15 N, lactate increase in 24 hour > 20%, and 3 CTA findings, namely, bowel dilation, bowel wall thickening, and mesenteric vasoconstriction. The area under the receiver operating characteristic was 0.82 (95% confidence interval [CI], 0.51-0.93) in the training cohort and 0.82 (95% CI, 0.68-0.96) in the validation cohort (n = 34 patients). Reliability of the predicted probabilities was greatest for probabilities ≤ 30% or ≥ 70%.

CONCLUSION

 In patients receiving intensive care after cardiothoracic surgery, GIisch cannot be ruled out based solely on CTA findings. A scoring system combining CTA findings with other variables may improve the diagnosis of GIisch in this population.

[Modern biochemical markers of acute mesenteric ischemia]

OBJECTIVE

To analyze modern literature data on biochemical markers of critical mesenteric ischemia.

MATERIAL AND METHODS

We analyzed the most promising, highly specific and sensitive biochemical markers of total and segmental intestinal damage following acute mesenteric ischemia. Analysis included domestic and foreign literature data between 2015 and 2023.

RESULTS

We identified the most easy-to-use for any hospitals biochemical markers with at least 90% sensitivity and specificity for further practical research.

CONCLUSION

Further prospective research will provide a new step in solving the problem of timely diagnosis of acute mesenteric circulatory disorders.

Acute mesenteric ischemia: A case report

Acute mesenteric ischemia is a rare life-threatening diagnostic and therapeutic emergency. Lack of clinical and biological specificity makes the diagnosis difficult. Imaging, particularly computed tomography can help confirm the diagnosis. An underlying cause is identified in about 30%-70% of cases and should always be sought. We report a case of a 51-year-old man with chronic alcoholic liver disease admitted to the emergency department for abdominal pain. Computed tomography showed mesenteric venous thrombosis with signs of small bowel ischemia and cirrhosis with portal hypertension. Through this observation, we describe the imaging aspects of mesenteric ischemia and emphasize the necessity of seeking underlying pathological condition.

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

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

First Line of Defense: The Vital Role of Family Medicine Physicians in Preventing Acute Mesenteric Ischemia in High-Risk Patients

Acute mesenteric ischemia (AMI) is a life-threatening condition with a high mortality rate despite surgical interventions. Morbidity and mortality are especially high in those with risk factors, which include diabetes mellitus (DM), hypertension (HTN), coronary artery disease, recent myocardial infarction, and rheumatic autoimmune diseases, among others. We present the case of a 70-year-old Caucasian woman diagnosed with AMI. The patient presented acutely to the emergency department after nine episodes of vomiting and was admitted to the surgical floor the same day for an emergent exploratory laparotomy. She presented acutely with an atypical presentation and without any progressive symptoms, despite various comorbidities. This patient was classified as "very high risk", but she had not been on any medications or monitored for any of her comorbidities. We highlight the essential and multifaceted role of family medicine physicians, also known as primary care physicians (PCPs), in the prevention of bowel ischemia and recommend the use of routine outpatient monitoring with clinical examination, blood testing, and imaging. These, along with a high index of suspicion, have clinical utility in preventing hospitalization, surgical intervention (bowel resection), and other serious sequelae of AMI. Timely detection, management, and specialist referrals from a family medicine physician can lower the overall burden on healthcare resources and personnel.

Role of spleen density in predicting postoperative complications in patients with acute mesenteric ischemia

BACKGROUND

Acute mesenteric ischemia (AMI) is a life-threatening surgical emergency with a poor prognosis. This study assessed the association of diffuse reduction of spleen density (DROSD) with postoperative complications and identified risk factors for adverse outcomes in AMI patients after surgery.

METHODS

Patients who were diagnosed with AMI and underwent surgical operations between April 2006 and July 2021 were enrolled. Spleen density was assessed using preoperative non-enhanced computed tomography. The lowest quartile of spleen density in all patients was regarded as the cutoff value for DROSD. Univariate and multivariate analyses were performed to determine the risk factors related to postoperative outcomes after surgery.

RESULTS

According to the diagnostic cutoff, patients with a spleen density ≤49.07 HU were defined as DROSD. In a cohort of 97 patients, 34.0% developed complications within 30 days of surgery. The multivariate analysis illustrated that DROSD was an independent risk factor for prognostic outcomes in AMI patients after surgery.

CONCLUSION

Patients with low spleen density were prone to postoperative complications. As an imaging method, preoperative assessment of spleen density is a novel predictor that can be used clinically to identify high-risk AMI patients with poor prognosis.

[Computed tomography diagnostics of acute and chronic mesenteric ischemia]

BACKGRAUND

Chronic mesenteric ischemia is more often accompanied by clinical signs characteristic of colitis. Acute mesenteric ischemia, unlike chronic, is accompanied by nonspecific symptoms and is a serious disease that requires urgent diagnosis.

AIMS

The aim of the study was to evaluate the effectiveness of MSCT in the diagnosis of acute and chronic mesenteric ischemia based on our observations.

MATERIALS AND METHODS

The retrospective study included 135 patients with abdominalgia and suspected mesenteric ischemia who underwent multiphase CT of the abdominal cavity with intravenous bolus contrast enhancement. Group 1 included 105 patients with mesenteric ischemia; group 2 included 30, without confirmed mesenteric ischemia, with the presence of a symptom of mesenteric ischemia in the form of abdominalgia.

RESULTS

We studied 135 patients, including 105 patients with mesenteric ischemia, 59 women and 46 men of average age 60±14.9 years. The acute form of ischemia (58%) was determined 1.5 times more often than the chronic one. Occlusive and nonocclusive acute mesenteric ischemia occurred in equal proportions. Mesenteric arterial thrombosis was the cause of acute mesenteric ischemia in 23% of cases. Mesenteric venous thrombosis was the cause of chronic intestinal ischemia in 61%, in 5% - acute form. Mixed arterial-venous genesis of mesenteric ischemia was determined in 4% against the background of strangulation obstruction. Dunbar syndrome as a cause of chronic intestinal ischemia was diagnosed in 16%. Chronic ischemic enterocolitis accounted for 10% of all cases of mesenteric ischemia and 23% of chronic ischemia. Symptoms and symptom complexes characteristic of the studied series of diseases with acute or chronic mesenteric ischemia were delineated. Sensitivity, specificity and prognostic value of CT with intravenous bolus contrast enhancement in diagnostics of diseases accompanied by mesenteric ischemia reached 100%.

CONCLUSIONS

Multiphase CT of the abdominal cavity with bolus contrast enhancement is highly informative in the diagnosis of acute and chronic forms of mesenteric ischemia. Direct CT signs of impaired blood flow in the arteries or veins of the mesentery were indisputable. Indirect signs of mesenteric ischemia were aimed at a thorough analysis of the condition of mesenteric vessels.

Are the conventional scoring systems efficient in predicting mortality of acute mesenteric ischemia?: Mortality estimation in patients with AMI

Acute mesenteric ischemia is a surgical emergency with high morbidity and mortality rates. Therefore, it is important to determine the prognosis for this disease. In the present study, we aimed to compare the prediction accuracy of 3 scoring systems: Acute physiology and chronic health evaluation II, sequential organ failure assessment score and simplified acute physiology score II (SAPS II). The retrospective cohort study was conducted in a university hospital. Eighty-two acute mesenteric ischemia patients were evaluated retrospectively. The mortality prediction abilities of the scoring systems were evaluated by comparing the prediction rates of > 10%, 30% and 50% and the actual mortality among survivors and non-survivors in pairs. Predicted mortality rates among survivors and non-survivors differed among the 3 classification systems. The mortality estimates of the SAPS II were closer to the actual mortality rates. Analysis of the estimated mortality rates as mortality risk limits showed that acute physiology and chronic health evaluation II was superior to sequential organ failure assessment score and SAPS II in estimating mortality rates, whereas SAPS II was more successful in detecting survivors. The estimated mortality rates of the 3 rating systems, the estimated mortality rates were higher in the non-survivor group than in the survivor group. The accuracy of the SAPS II in determining prognosis was relatively better.

Relationship between subarachnoid hemorrhage and nonocclusive mesenteric ischemia as a fatal complication: patient series

BACKGROUND

Nonocclusive mesenteric ischemia (NOMI) causes intestinal necrosis due to irreversible ischemia of the intestinal tract. The authors evaluated the incidence of NOMI in patients with subarachnoid hemorrhage (SAH) due to ruptured aneurysms, and they present the clinical characteristics and describe the outcomes to emphasize the importance of recognizing NOMI.

OBSERVATIONS

Overall, 7 of 276 consecutive patients with SAH developed NOMI. Their average age was 71 years, and 5 patients were men. Hunt and Kosnik grades were as follows: grade II, 2 patients; grade III, 3 patients; grade IV, 1 patient; and grade V, 1 patient. Fisher grades were as follows: grade 1, 1 patient; grade 2, 1 patient; and grade 3, 5 patients. Three patients were treated with endovascular coiling, 3 with microsurgical clipping, and 1 with conservative management. Five patients had abdominal symptoms prior to the confirmed diagnosis of NOMI. Four patients fell into shock. Two patients required emergent laparotomy followed by second-look surgery. Four patients could be managed conservatively. The overall mortality of patients with NOMI complication was 29% (2 of 7 cases).

LESSONS

NOMI had a high mortality rate. Neurosurgeons should recognize that NOMI can occur as a fatal complication after SAH.

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.

Abdominal imaging in ICU patients with viral pneumonia: Are findings in COVID-19 patients really different from those observed with non-SARS-CoV-2 viral pneumonia?

Purpose

To evaluate and compare the prevalence and type of abdominal involvements identified on CT scans in COVID-19 critically ill patients to those observed in critically ill patients with non-SARS-CoV-2 viral pneumonia.

Methods

Monocentric IRB approved retrospective study comparing all abdominal CT scans performed for patients admitted in the ICU with COVID-19 and those performed in a historical cohort of ICU patients with non-SARS-CoV-2 viral pneumonia. For each patient, gallbladder abnormality, acute pancreatitis signs, acute adrenal infarction, renal infarcts, bowel wall thickening and CT scan signs of bowel ischemia were assessed. Results were then compared between critically ill COVID-19 and non-COVID-19 patients (Chi-2 or Fisher exact tests for categorical data and Student t-test or Mann-Whitney U test for continuous data as appropriate).

Results

Ninety-nine COVID-19 patients and 45 non-COVID-19 patients were included.

No difference was found between the rate of abnormal findings comparing COVID-19 patients and patients with other viral pneumonia (63/99 [64%] vs 27/45 [61%], p=0.94). Acute pancreatitis signs were more commonly seen in COVID-19 patients but without statistically difference between groups (14/99 [14%] vs 3/45 [6.7%], p=0.31). Bowel wall thickening was slightly more commonly seen in patients with other viral pneumonia (18/99 [18%] vs 11/45 [24%], p=0.52), however ischemic features were observed in higher rate in the COVID-19 group, although without reaching statistically significant differences (7/99 [7.1%] vs 2/45 [4.4%], p=0.75).

Conclusion

The rate and severity of abdominal involvement demonstrated by CT in ICU patients hospitalized for COVID-19 although high were not different to that observed in patients with other severe viral pneumoniae

Acute appendicitis complicated by mesenteric vein thrombosis: A case report

BACKGROUND

Acute appendicitis with mesenteric vein thrombosis (MVT) is an uncommon condition and usually lacks specific clinical manifestations, which leads to a high rate of misdiagnosis or delayed diagnosis, especially when it is accompanied by other abdominal diseases. Prompt and accurate recognition is vital for treatment and prognosis.

CASE SUMMARY

A 37-year-old woman had a history of acute metastatic right lower abdominal pain, nausea, and fever. A contrast-enhanced computed tomography (CT) scan showed a filling defect in the mesenteric vessels. The patient was diagnosed with acute appendicitis complicated by MVT and was treated with anticoagulation and intravenous antibiotics. The follow-up CT scan showed full resolution of the thrombosis and inflammation.

CONCLUSION

Clinical awareness is essential for recognizing MVT, especially when it is accompanied by other common acute abdominal diseases, such as acute appendicitis. Contrast-enhanced CT is helpful for the diagnosis of MVT and is recommended for patients with acute abdominal diseases.

Multidetector computed tomography: a corner stone imaging modality in evaluation of acute small bowel diseases

Background

The diagnosis of acute small bowel diseases is one of the challenging issues that confronted by the radiologists so accurate diagnosis is essential to determine the appropriate way of management. CT has become the preferred imaging tool to evaluate acute small bowel diseases. Our study aimed to assess the role of MDCT in evaluation of acute abdomen secondary to small bowel origin by identification and differentiation between different acute small bowel pathologies.

Results

Thirty-eight patients presented with acute abdomen of small bowel origin from June 2019 to September 2019. The mean age of incidence was 48 ± 19 years ranged from 4 to 88 years. Males represented by 23 patients (60.5%). Acute exacerbation of inflammatory bowel diseases (Crohn’s disease) represented by (34.2%), small bowel obstruction (31.6%), ischemic bowel diseases (21.1%), small bowel perforation (10.5%) and infectious (TB enteritis) small bowel disease (2.6%). MDCT had an overall high sensitivity (97.3%) in assessment of acute small bowel diseases in correlation with post-operative data and follow-up response to management.

Conclusions

MDCT is a reliable diagnostic imaging tool for assessment of patients with acute abdomen secondary to small bowel origin with high-efficiency in differentiation between different pathological entities that causing acute abdomen.

Incidence of contrast-induced acute kidney injury in patients with acute mesenteric ischemia and identification of potential predictive factors

OBJECTIVE

Contrast-enhanced computed tomography angiography (CTA) is commonly used to investigate acute abdominal conditions, but the risk of contrast-induced acute kidney injury (CI-AKI) has been poorly investigated in patients with acute mesenteric ischemia. The aim of the present study was to evaluate the incidence of CI-AKI in these patients and identify potential predictive factors.

METHODS

Patients admitted for acute mesenteric ischemia who had a diagnostic CTA with contrast medium and a follow-up of creatinine concentration were retrospectively included.

RESULTS

Among 53 patients included, 9 (16.9%) developed CI-AKI. The prevalence of chronic kidney disease did not differ significantly between those who developed CI-AKI and those who did not (33.3 vs 18.2%, p=.372). Plasma total bilirubin and conjugated bilirubin levels were significantly higher in patients who developed CI-AKI (17.5 vs 8.0 μmol/L, p=.013 and 8.0 vs 3.0 μmol/L, p=.031, respectively). The proportion of patients who had revascularization was similar between patients who developed CI-AKI and those who did not (11.1 vs 20.5%, p>.999). No significant difference was observed for 30-day mortality and all-cause mortality for a median follow-up of 168 days (22.2 vs 13.6%, p=.611; and 33.3 vs 61.4%, p=.153, respectively).

CONCLUSION

This study reports the incidence of CI-AKI in patients with acute mesenteric ischemia after diagnostic CTA with contrast medium. Plasma bilirubin levels were a predictive factor of CI-AKI in these patients. The administration of contrast media during revascularization was not associated with an increased risk of CI-AKI.

Photoacoustic imaging in evaluating early intestinal ischemia injury and reperfusion injury in rat models

Background

It remains a challenge to distinguish whether the damaged intestine is viable in treating acute mesenteric ischemia. In this study, photoacoustic imaging (PAI) was used to observe intestinal tissue viability after ischemia and reperfusion injury in rats.

Methods

An in vivo study was conducted using forty male SD rats, which were randomly divided into a sham-operated (SO) group, a 1 h ischemia group, a 2 h ischemia group, and an ischemia-reperfusion (I/R) group with 10 rats in each group. In the ischemia group, the superior mesenteric artery (SMA) was isolated and clamped for 1 and 2 h, respectively, and in the I/R group, after ischemia for 1 h, the clamp was removed and reperfused for 1 h. The same time interval was used in the SO group. Immediately after establishing the animal model, a PAI examination was performed, and the small intestine was collected for histopathology.

Results

The levels of PAI parameters Hb, HbR, MAP 760, and MAP 840 were increased to different degrees in the ischemia groups, especially in the 2 h ischemia group, compared with the SO group (P<0.05), and with prolongation of the ischemia time, the injury was aggravated. All PAI signal levels except HbO in the I/R group were higher than those in the control group, and the increased range differed, especially in Hb and MAP 840. Using western blot, compared with the SO group, the BAX increased significantly in the 2 h ischemia group (P<0.05), and Caspase-3 in the experimental group was significantly higher than in the SO group (P<0.05). The level of HIF-1α increased in the 2 h ischemia group and I/R group (P<0.05), and TUNEL staining showed that the number of positive apoptotic nuclei in the 2 h ischemia group was significantly higher than in the SO group (P<0.05). Hematoxylin-eosin (HE) staining showed that ischemia for 2 hours was the most serious, with obvious mucosal damage, extensive epithelial injury, and bleeding.

Conclusions

PAI can be used as an effective tool to detect acute intestinal ischemia injury and quantitatively evaluate tissue viability.

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.

Large Bowel Ischemia/Infarction: How to Recognize It and Make Differential Diagnosis? A Review

Ischemic colitis represents the most frequent form of intestinal ischemia occurring when there is an acute impairment or chronic reduction in the colonic blood supply, resulting in mucosal ulceration, inflammation, hemorrhage and ischemic necrosis of variable severity. The clinical presentation is variable and nonspecific, so it is often misdiagnosed. The most common etiology is hypoperfusion, almost always associated with generalized atherosclerotic disease. The severity ranges from localized and transient ischemia to transmural necrosis of the bowel wall, becoming a surgical emergency, with significant associated morbidity and mortality. The diagnosis is based on clinical, laboratory suspicion and radiological, endoscopic and histopathological findings. Among the radiological tests, enhanced-CT is the diagnostic investigation of choice. It allows us to make the diagnosis in an appropriate clinical setting, and to define the entity of the ischemia. MR may be adopted in the follow-up in patients with iodine allergy or renal dysfunctions, or younger patients who should avoid radiological exposure. In the majority of cases, supportive therapy is the only required treatment. In this article we review the pathophysiology and the imaging findings of ischemic colitis.

Pneumatosis intestinalis and portal venous gas in mechanical small bowel obstruction: Is it worrisome?

PURPOSE

The purpose of this study was to evaluate the clinical significance of pneumatosis intestinalis (PI) and portal venous gas (PVG) in patients with mechanical small bowel obstruction (SBO), using surgical findings or clinical follow-up as standard of reference.

MATERIALS AND METHODS

Fourteen patients with mechanical SBO associated with PI and PVG were retrospectively included. There were 7 men and 7 women with a mean age of 59±19 (SD) (range: 25-93 years). CT examinations were reviewed by two radiologists to confirm the diagnosis of mechanical SBO and make a description of PI. Interobserver agreement was calculated. The reference standard was intraoperative appearance of the bowel wall (10/14; 71%) or the recovery of a normal bowel function in patients who were managed conservatively (4/14; 29%).

RESULTS

Among the 10 patients who underwent surgery, a normal appearance of the bowel in association with PI on CT was found intraoperatively in 8/10 (80%) patients and a reversible ischemia in the remaining 2/10 (20%) patients. The four patients who were managed conservatively recovered normal bowel function. Two patients died within two weeks following SBO.

CONCLUSION

PI and PVG are not specific signs of bowel necrosis in mechanical SBO.

Many faces of acute bowel ischemia: overview of radiologic staging

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

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

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

Influence of clinical suspicion on CT accuracy of acute mesenteric ischemia: Retrospective study of 362 patients

PURPOSE

Acute mesenteric ischemia (AMI) may be underdiagnosed when not clinically suspected before CT is performed. We assessed the influence of a clinical suspicion of AMI on the CT accuracy.

METHOD

This retrospective single-centre study included patients who underwent CT in 2014-2019 and had clinically suspected AMI and/or confirmed AMI. CT protocols were adapted based on each patient's presentation and on findings from unenhanced images. The CT protocol was considered optimal for AMI when it included arterial and portal venous phases. CT protocols, accuracy of reports, and outcomes were compared between the groups with and without suspected AMI before CT.

RESULTS

Of the 375 events, 337 (90 %) were suspected AMI and 66 (18 %) were AMI, including 28 (42 %) with and 38 without suspected AMI. These two groups did not differ significantly regarding the medical history, clinical presentation, or laboratory tests. The CT protocol was more often optimal for AMI in the group with suspected AMI (26/28 [93 %] vs. 28/38 [74 %], p = 0.046). Diagnostic accuracy was not different between groups with and without suspected AMI (26/28 [93 %] vs. 34/38 [90 %], p = 1.00). However, it was lower in the group without suspicion of AMI when the CT protocol was not optimal for AMI (27/28 [96 %] vs 7/10 [70 %], p = 0.048).

CONCLUSIONS

The negative influence of not clinically suspecting AMI can be mitigated by using a tailored CT protocol.

Diagnostic performance of CT for the detection of transmural bowel necrosis in non-occlusive mesenteric ischemia

OBJECTIVES

To evaluate the diagnostic performance of CT for transmural necrosis (TN) in non-occlusive mesenteric ischemia (NOMI) according to the bowel segment involved.

METHODS

From January 2009 to December 2019, all patients admitted to the intensive care unit (ICU) and requiring laparotomy for NOMI were retrospectively studied. CT had to have been performed within 24 h prior to laparotomy and were reviewed by two abdominal radiologists, with a consensus reading in case of disagreement. A set of CT features of mesenteric ischemia were assessed, separating the stomach, jejunum, ileum, and right (RC) and left colon (LC). Univariate and multivariate analyses were performed to identify features associated with TN. Its influence on overall survival (OS) was assessed.

RESULTS

Among 145 patients, 95 (66%) had ≥ 1 bowel segment with TN, including 7 (5%), 31 (21%), 43 (29%), 45 (31%), and 52 (35%) in the stomach, jejunum, ileum, RC, and LC, respectively. Overall inter-reader agreement of CT features was significantly lower in the colon than in the small bowel (0.59 [0.52-0.65] vs 0.74 [0.70-0.77] respectively). The absence of bowel wall enhancement was the only CT feature associated with TN by multivariate analysis, whatever the bowel segment involved. Proximal TN was associated with poorer OS (p < 0.001).

CONCLUSIONS

The absence of bowel wall enhancement remains the most consistent CT feature of transmural necrosis, whatever the bowel segment involved in NOMI. Inter-reader agreement of CT features is lower in the colon than in the small bowel. Proximal TN seems to be associated with poorer OS.

KEY POINTS

• The absence of bowel wall enhancement is the most consistent CT feature associated with transmural necrosis in NOMI, whatever is the bowel segment involved. • Inter-reader agreement is lower in the colon than in the small bowel in NOMI. • In NOMI, the more proximal the bowel necrosis, the worse the prognosis.

Quadrifurcation Variants of the Celiac Trunk

BACKGROUND

The celiac trunk (CT) commonly trifurcates into the left gastric artery, common hepatic artery (CHA), and splenic artery (SA). The CHA then sends off the proper hepatic artery and gastroduodenal artery (GDA). The arcades of the head of the pancreas are celiacomesenteric anastomoses between branches of the GDA and the superior mesenteric artery. A quadrifurcation of the CT commonly occurs when a different branch is added to the 3 normal ones. An uncommon quadrifurcation of the CT occurs when only one or 2 of the normal branches of the CT participate.

METHODS

The CT quadrifurcations were documented on 112 computed tomography angiograms.

RESULTS

Five different types of CT quadrifurcation-3 uncommon (types 1-3) and 2 common (types 4-5)-were found in 15/112 cases (13.39%). A marginal significant association was found between the presence of quadrifurcations and male gender (P = 0.05; Fisher's exact test). Type 1 showed a hepatogastric trunk+SA + right hepatic artery+GDA pattern, type 2 had an HGT + right inferior phrenic artery + CHA + SA pattern, type 3 had a gastrophrenic trunk + left inferior phrenic artery+CHA + SA pattern, type 4 showed an left gastric artery + CHA + SA + left inferior phrenic artery combination, and type 5 had an additional common inferior phrenic trunk. One of the type 4 cases showed a buildup of a mesentericomesenteric anastomotic pancreatic arcade between the inferior pancreaticoduodenal arteries, rather than a celiacomesenteric one.

CONCLUSIONS

Anatomic variation of the celiacomesenteric axis is important during hepatobiliary and duodenopancreatic approaches. Therefore, preoperative evaluation is essential because theoretical anatomic possibilities could be real arterial variants.

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.

Risk factors of geriatrics index of comorbidity and MDCT findings for predicting mortality in patients with acute mesenteric ischemia due to superior mesenteric artery thromboembolism

OBJECTIVES

To identify risk factors of geriatrics index of comorbidity (GIC) and multidetector CT (MDCT) findings for predicting mortality in patients with acute mesenteric ischemia (AMI) due to superior mesenteric artery (SMA) thromboembolism.

METHODS

33 patients with AMI due to SMA thromboembolism underwent abdominal MDCT and angiography. Patients' comorbidities and MDCT findings of ischemic bowel/mesenteric injuries, regions of SMA involved by thromboembolism, and degrees of SMA stenosis were retrospectively reviewed. The comorbidities were classified into 1-4 levels according to GIC. The association of MDCT signs and GIC classification with mortality were analyzed. Diagnostic performances of risk factors associated with mortality were evaluated by receiver operating characteristic (ROC) curve analyses.

RESULTS

Eighteen patients (54.5%) died during hospitalization or follow-up, including one patient with class 1, two patients with class 2, eight patients with class 3, and seven patients with class 4 according to GIC. Three risk factors significantly associated with mortality were identified, including pneumatosis and/or portomesenteric venous gas (PPMVG) (p = 0.017), four regions of SMA involved by thromboembolism (region I + II + III + IV) (p = 0.036), and class 3 + 4 of comorbidities (p = 0.001). The sensitivity and specificity of PPMVG, region I + II + III + IV, class 3 + 4 of comorbidities, and the three risk factors combined for diagnosing mortality were 33.3 and 100%, 27.8 and 100%, 83.3 and 73.3%, and 88.9 and 73.3%, respectively. The areas under the ROC curve (AUC) of the three risk factors combined (0.88) and class 3 + 4 of comorbidities (0.78) were larger than that of PPMVG (0.67) and region I + II + III + IV (0.64). The mortality rate rose from 15.4% in patients without risk factor to 66.7%, 100%, and 100% in patients with one, two, and three factors, respectively.

CONCLUSION

Three risk factors for mortality were identified in patients with AMI due to SMA thromboembolism, including PPMVG and four regions of SMA involved by thromboembolism on MDCT images, and class 3 + 4 of comorbidities. Close monitoring of these risk factors could possibly lower the mortality.

ADVANCES IN KNOWLEDGE

Risk factors based on GIC and MDCT findings may be used to predict mortality in patients with AMI. Close monitoring of these risk factors could possibly lower the mortality.

Atherosclerosis is associated with poorer outcome in non-occlusive mesenteric ischemia

PURPOSE

To evaluate whether abdominal atherosclerosis was associated with poorer outcome in a single-centre cohort of patients suffering from nonocclusive mesenteric ischemia (NOMI).

METHODS

From January 2009 to December 2019, 121 consecutive patients from the critical care unit who underwent laparotomy for suspected NOMI and with available unenhanced and contrast-enhanced CT were included. Clinical and biological data at the time of the CT scan were retrospectively extracted from medical charts and reviewed by a single radiologist. Unenhanced CT acquisitions were used to calculate calcium scores of the abdominal aorta, celiac trunk, superior mesenteric artery (SMA) and common iliac arteries according to the Agatston method. Univariate and multivariate analysis were performed.

RESULTS

Among the 121 patients with NOMI and calcium score calculation, only 4 patients had no aortic calcifications (3 %) and 32 had no superior mesenteric artery calcification (26 %). 35 patients (29 %) died within 24 h after the abdominal CT scan. Univariate analysis showed that a total abdominal calcium score greater than 15 000 (last quartile) was significantly associated with death within 24 h (14 (40 %) vs 17 (20 %) patients, p = 0.035). By multivariate analysis, a total abdominal calcium score greater than 15 000 was an independent risk factor for death (HR = 1.94, 95 %CI [1.02-3.73], p = 0.044). Regarding separate calcium scores, only a SMA calcium score greater than 50 was a risk factor for death (HR 2.46, 95 %CI [1.14-3.93], p = 0.019).

CONCLUSION

Our results show that abdominal atherosclerosis, especially in the SMA, is associated with poorer outcome in NOMI.

Predictors of mortality following emergency open colectomy for ischemic colitis: a single-center experience

Background

Ischemic colitis (IC) is a severe emergency in gastrointestinal surgery. The aim of the present study was to identify the predictors of postoperative mortality after emergent open colectomy for IC treatment. Additionally, we compared postoperative outcomes of patients undergoing emergent colectomy due to aortic surgery-related IC (AS-IC group) vs. other IC etiologies (Other-IC group).

Methods

We analyzed records of consecutive patients who underwent emergency open colectomy for IC between 2008 and 2019. Logistic regression analysis was performed to identify clinical and operative parameters associated with postoperative mortality. The AS-IC and Other-IC groups were compared for mortality, morbidity, ICU stay, hospital stay, and survival.

Results

During the study period, 94 patients (mean age, 67.4 ± 13.7 years) underwent emergent open colectomy for IC. In the majority of cases, IC involved the entire colon (53.2%) and vasopressor agents were required preoperatively (63.8%) and/or intraoperatively (78.8%). Thirty-four patients underwent surgery due to AS-IC, whereas 60 due to Other-IC causes. In the AS-IC group, 9 patients had undergone endovascular aortic repair and 25 open aortic surgery; 61.8% of patients needed aortic surgery for ruptured abdominal aortic aneurism (AAA). Overall, 66 patients (70.2%) died within 90 days from surgery. The AS-IC and Other-IC groups showed similar operative outcomes and postoperative complication rates. However, the duration of the ICU stay (19 days vs. 11 days; p = 0.003) and of the total hospital stay (22 days vs. 16 days; p = 0.016) was significantly longer for the AS-IC group than for the Other-IC group. The rate of intestinal continuity restoration at 1 year after surgery was higher for the Other-IC group than for the AS-IC group (58.8% vs. 22.2%; p = 0.05). In the multivariate model, preoperative increased lactate levels, a delay between signs/symptoms’ onset and surgery > 12 h, and the occurrence of postoperative acute kidney injury were statistically associated with postoperative mortality. Neither IC etiology (aortic surgery vs. other etiology) nor ruptured AAA was associated with postoperative mortality.

Conclusion

Emergency open colectomy for IC is associated with high postoperative mortality, which appears to be unrelated to the IC etiology. Preoperative lactate levels, > 12-h delay to surgery, and postoperative acute kidney injury are independent predictors of postoperative mortality.

Acute mesenteric ischaemia in refractory shock on veno-arterial extracorporeal membrane oxygenation

BACKGROUND

Acute mesenteric ischaemia is a severe complication in critically ill patients, but has never been evaluated in patients on veno-arterial extracorporeal membrane oxygenation (V-A ECMO). This study was designed to determine the prevalence of mesenteric ischaemia in patients supported by V-A ECMO and to evaluate its risk factors, as well as to appreciate therapeutic modalities and outcome.

METHODS

In a retrospective single centre study (January 2013 to January 2017), all consecutive adult patients who underwent V-A ECMO were included, with exclusion of those dying in the first 24 hours. Diagnosis of mesenteric ischaemia was performed using digestive endoscopy, computed tomography scan or first-line laparotomy.

RESULTS

One hundred and fifty V-A ECMOs were implanted (65 for post-cardiotomy shock, 85 for acute cardiogenic shock, including 39 patients after refractory cardiac arrest). Overall, median age was 58 (48-69) years and mortality 56%. Acute mesenteric ischaemia was suspected in 38 patients, with a delay of four (2-7) days after ECMO implantation, and confirmed in 14 patients, that is, a prevalence of 9%. Exploratory laparotomy was performed in six out of 14 patients, the others being too unstable to undergo surgery. All patients with mesenteric ischaemia died. Independent risk factors for developing mesenteric ischaemia were renal replacement therapy (odds ratio (OR) 4.5, 95% confidence interval (CI) 1.3-15.7, p=0.02) and onset of a second shock within the first five days (OR 7.8, 95% CI 1.5-41.3, p=0.02). Conversely, early initiation of enteral nutrition was negatively associated with mesenteric ischaemia (OR 0.15, 95% CI 0.03-0.69, p=0.02).

CONCLUSIONS

Acute mesenteric ischaemia is a relatively frequent but dramatic complication among patients on V-A ECMO.

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.