Reperfusion in non-occlusive mesenteric ischaemia (NOMI): effectiveness of CT in an emergency setting

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.

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.

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.

MDCT-findings in patients with non-occlusive mesenteric ischemia (NOMI): influence of vasoconstrictor agents

OBJECTIVES

To evaluate the influence of vasoconstrictor agents (VCAs) on signs of vasoconstriction and bowel ischemia on MDCT detected in patients with non-occlusive mesenteric ischemia (NOMI).

METHODS

This 8-year single-center retrospective study consecutively included all patients with histopathologically proven NOMI who underwent MDCT ≤ 48 h prior to surgical bowel resection. Two blinded radiologists jointly reviewed each examination for signs of bowel ischemia, abdominal organ infarct, mesenteric vessel size and regularity, and ancillary vascular findings. VCA administration (length and dosage), clinical and biochemical data, risk factors, and outcomes were retrieved from patients' medical records. Subgroup comparisons were performed.

RESULTS

Ninety patients were included (59 males, mean age 65 years); 40 (44.4%) had received VCAs before MDCT. Overall mortality was 32% (n = 29), with no significant difference between the two groups. In patients treated with VCAs, the calibre of the superior mesenteric artery (SMA) was smaller (p = 0.032), and vasoconstriction of its branches tended to be more important (p = 0.096) than in patients not treated with VCAs. The presence and extent of bowel ischemia did not significantly correlate with VCA administration, but abdominal organ infarcts tended to be more frequent (p = 0.005) and involved more organs (p = 0.088). The VCA group had lower mean arterial pressure (p = 0.006) and lower hemoglobin levels (p < 0.001). Several biomarkers of organ failure and inflammation, differed significantly with VCA use, proving worse clinical condition.

CONCLUSIONS

MDCT demonstrates more severe SMA vasoconstriction and tends to show increased abdominal organ infarcts after VCA administration in NOMI patients compared to NOMI patients not treated with VCAs.

KEY POINTS

• In critically ill patients with NOMI, MDCT demonstrates VCA support via increased vasoconstriction of the main SMA and its branches. • VCA administration in NOMI patients tends to contribute to the development of organ infarcts, as shown on MDCT. • An important degree of vasoconstriction in NOMI patients may indicate insufficient resuscitation and, thus, help clinicians in further patient management.

Advances in the diagnosis of non-occlusive mesenteric ischemia and challenges in intra-abdominal sepsis patients: a narrative review

Non-occlusive mesenteric ischemia (NOMI) is a type of acute mesenteric ischemia (AMI) with a high mortality rate mainly because of a delayed or misdiagnosis. Intra-abdominal sepsis is one of the risk factors for developing NOMI, and its presence makes early diagnosis much more difficult. An increase in routine abdominal surgeries carries a corresponding risk of abdominal infection, which is a complication that should not be overlooked. It is critical that physicians are aware of the possibility for intestinal necrosis in abdominal sepsis patients due to the poor survival rate of NOMI. This review aims to summarize advances in the diagnosis of NOMI, and focuses on the diagnostic challenges of mesenteric ischemia in patients with intra-abdominal sepsis.

Reperfusion injury on computed tomography following endovascular revascularization of acute mesenteric ischemia: prevalence, risk factors, and patient outcome

BACKGROUND

Data about reperfusion injury (RI) following acute arterial mesenteric ischemia (AAMI) in humans are scarce. We aimed to assess the prevalence and risk factors of RI following endovascular revascularization of AMI and evaluate its impact on patient outcomes.

METHODS

Patients with AAMI who underwent endovascular revascularization (2016-2021) were included in this retrospective cohort. CT performed < 7 days after treatment was reviewed to identify features of RI (bowel wall hypoattenuation, mucosal hyperenhancement). Clinical, laboratory, imaging, and treatments were compared between RI and non-RI patients to identify factors associated with RI. Resection rate and survival were also compared.

RESULTS

Fifty patients (23 men, median 72-yrs [IQR 60-77]) were included, and 22 were diagnosed with RI (44%) after a median 28 h (22-48). Bowel wall hypoattenuation and mucosal hyperenhancement were found in 95% and 91% of patients with post-interventional RI, respectively. Patients with RI had a greater increase of CRP levels after endovascular treatment (p = 0.01). On multivariate analysis, a decreased bowel wall enhancement on baseline CT (HR = 8.2), an embolic cause (HR = 7.4), complete SMA occlusion (HR = 7.0), and higher serum lactate levels (HR = 1.4) were associated with RI. The three-month survival rate was 78%, with no difference between subgroups (p = 0.99). However, the resection rate was higher in patients with RI (32% versus 7%; p = 0.03).

CONCLUSION

RI is frequent after endovascular revascularization of AAMI, especially in patients who present with decreased bowel wall enhancement on pre-treatment CT, an embolic cause, and a complete occlusion of the SMA. However, its occurrence does not seem to negatively impact short-term survival.

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.

Intestinal pneumatosis: differential diagnosis

Intestinal pneumatosis (IP) is an infrequent radiological sign defined as pathological gas infiltration into the bowel wall. It may be associated to different underlying clinical conditions-inflammatory bowel diseases, malignancies, chemotherapy, infections, immune deficiency status, trauma, intestinal ischemia, and necrosis-that are often related to emergency state and require a prompt diagnosis. All the imaging techniques, especially abdominal radiography and Computed Tomography, could detect the presence of IP and discern the forms related to emergency conditions. The differential diagnosis is essential to start an immediate clinical or surgical management and treatment. The aim of this article is to review the radiological features of IP in different illnesses, with particular attention to differential diagnosis.

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.

Computed-tomography angiography in arterial acute intestinal ischemia: prognostic interest of vascular semiology

PURPOSE

To investigate vascular features on abdominal Computed-Tomography Angiography (CTA) correlated with 48-h mortality in patients who underwent arterial acute intestinal ischemia (AAII) surgery. The secondary objective was to create a prognostic score on the 48-h mortality after surgery, based on the most relevant signs.

METHOD

We included 104 patients who underwent surgery for acute mesenteric ischemia. 2 radiologists retrospectively blind reviewed the preoperative CTA scans. They used a standardized analysis grid for the arterial and venous vascular signs described in angiography. When signs were present, the affected abdominal quadrant was specified in coronal reconstruction. Each sign was analyzed for 48-h mortality on CTA. A score based on signs correlated with early mortality was developed and evaluated by ROC curve analysis.

RESULTS

22 patients died within 48 h. The number of superior mesenteric artery (SMA) branches was significantly reduced in deceased patients (p = 0.006). Other prognostic factors associated with 48-h mortality were decreased venous return in area number 1 corresponding to right colic flexure, proximal half of the transverse colon, proximal ileum (p = 0.04) and decreased venous return in more than 2 zones (p = 0.01). The weighted AAII48 score included 1 protective clinical item and 5 radiological items. The area under the ROC curve was 0.784 with, for a 6-point threshold value, a sensitivity of 68% and a specificity of 77%. The intraclass correlation coefficient for interobserver reproducibility of the score was 0.81 [95% CI 0.73; 0.87].

CONCLUSION

Three vascular signs on CTA were found to be prognostic factors for early mortality: SMA branches number ≤ 5 (p = 0.006), decreased venous return in area 1 (p = 0.04), and > 2 areas of decreased venous return (p = 0.01). They were incorporated into the AAII48 score. This score could help to identify patients at risk and to adapt subsequent management.

Non-invasive assessment of mesenteric hemodynamics in patients with suspected chronic mesenteric ischemia using 4D flow MRI

PURPOSE

Chronic mesenteric ischemia (CMI) is a rare disease with a particularly difficult diagnosis. In this study, 4D flow MRI is used to quantitatively evaluate mesenteric hemodynamics before and after a meal in patients suspected of having CMI and healthy individuals.

METHODS

Nineteen patients suspected of CMI and twenty control subjects were analyzed. Subjects were scanned using a radially undersampled 4D flow MR sequence (PC-VIPR). Flow rates were assessed in the supraceliac (SCAo) and infrarenal aorta, celiac artery, superior mesenteric artery (SMA), left and right renal arteries, superior mesenteric vein (SMV), splenic vein, and portal vein (PV) in a fasting state (preprandial) and 20 min after a 700-kcal meal (postprandial). Patients were subcategorized into positive diagnosis (CMI+, N = 6) and negative diagnosis (CMI-, N = 13) groups based on imaging and clinical findings. Preprandial, postprandial, and percent change in flow rates were compared between subgroups using a Welch t test.

RESULTS

In controls and CMI- patients, SCAo, SMA, SMV, and PV flow increased significantly after meal ingestion. No significant flow increases were observed in CMI+ patients. Percent changes in SMA, SMV, and PV flow were significantly greater in controls compared to CMI+ patients. Additionally, percent changes in flow in the SMV and PV were significantly greater in CMI- patients compared to CMI+ patients.

CONCLUSIONS

4D flow MRI with large volumetric coverage demonstrated significant differences in the redistribution of blood flow in SMA, SMV, and PV in CMI+ patients after a meal challenge. This approach may assist in the challenging diagnosis of CMI.

Errors in MDCT diagnosis of acute mesenteric ischemia

The causes of diagnostic errors during daily medical practice can be several, mainly attributable to perceptual, interpretive and communication factors. The eventuality of radiological error is much more amplified in the emergency setting where a high number of complex multidetector-row computed tomography (MDCT) images must be evaluated quickly and critical time decisions need to be taken. In particular, in this context, the diagnosis of vascular intestinal diseases represents a crucial and difficult challenge in case of acute abdominal pain given the importance of being able to identify patient with high suspicious for intestinal ischemia and for a specific patient to judge if his ischemia is reversible or irreversible. Awareness of potential biases which can lead to diagnostic errors together with an extensive knowledge of the imaging features of these pathologies can lead to promptly recognize them with fewer mistakes, improving patients' outcome. This article reviews the MDCT findings of acute intestinal ischemia and acute colonic ischemia and analyzes the main types of diagnostic errors, underlining the importance of being familiarized with them to avoid misdiagnosis.

Small bowel obstruction and intestinal ischemia: emphasizing the role of MDCT in the management decision process

The objective of this article is to assess the computed tomography (CT) findings of small bowel obstruction (SBO) complicated by ischemia. SBO is a frequent clinical entity characterized by high morbidity and mortality. The radiologic aim is not just to diagnose the obstruction itself but to rule out the presence of complications related to SBO. This is crucial for differentiating which patients can be safely treated non-operatively from the ones who may need an urgent surgical approach. The main complication of SBO is intestinal ischemia. In the emergency setting, CT imaging is the modality of choice for SBO because of its ability to assess the bowel wall, the supporting mesentery and peritoneal cavity all in one. On the other hand, the radiologist who documents an intestinal ischemia should think about SBO as possible cause. In this case, the main finding which helps the radiologist in the identification of SBO is the presence of multiple and packed valvulae conniventes in the dilated bowel wall and the "transition zone" that indicates the passage between compressed and decompressed small bowel, otherwise the localization of the obstruction cause. Once the site of obstruction has been recognized, the other issue is to assess the cause of obstruction, considering that the most common cause of SBO remains "unidentified" and related to intra-abdominal adhesions. After that, the following most important point is to rule out the presence of an ischemic bowel and mesenteric changes associated to SBO. CT signs of bowel ischemia include reduced or increased bowel wall enhancement, mesenteric edema or engorgement, fluid or free air in the peritoneal cavity. This condition usually leads to an urgent laparotomy and, in some cases, to a surgical resection.

Contrast-enhanced ultrasonographic findings of non-occlusive mesenteric ischemia: a case series

PURPOSE

Diagnosis of non-occlusive mesenteric ischemia (NOMI) is difficult, with diagnostic imaging being mainly performed using angiography or contrast-enhanced computed tomography. Contrast-enhanced ultrasonography (CEUS) offers an alternative diagnostic method, although diagnosis of NOMI using CEUS is not common. In this report, we review CEUS findings in a series of patients with NOMI.

METHODS

The records of patients diagnosed with NOMI who underwent a surgical procedure in our institution between January 2015 and February 2020 were retrospectively assessed. Grayscale ultrasonography and CEUS findings were evaluated.

RESULTS

Ten patients (mean age 65 ± 25 years, 7 men) were studied. Grayscale ultrasonography revealed bowel dilatation, the presence of intestinal pneumatosis, portal venous gas, bowel wall thickening, and no or decreased peristalsis. A CEUS finding of note was a partial lack of enhancement of the bowel wall.

CONCLUSION

In a small case series of 10 patients with surgically/histopathology confirmed NOMI, partial lack of ultrasound contrast-enhancement of the bowel wall was observed.

Non-occlusive mesenteric ischemia (NOMI) and prognostic signs at CT: reperfusion or not reperfusion that is the question!

PURPOSE

Non-occlusive mesenteric ischemia (NOMI) is a misdiagnosed and dangerous condition. To our knowledge, a comprehensive evaluation of CT parameters that can predict the outcome of patients suffering from NOMI is still missing.

MATERIALS AND METHODS

Contrast-enhanced CT examination of 84 patients with a confirmed diagnosis of NOMI (37 with clinical and laboratory confirmation and 47 biopsy or surgery proven) was retrospectively reviewed by assessing vessels, mesentery, bowel, and peritoneal cavity CT quantitative and dichotomous parameters, and data were analyzed with Fisher's test. Diameter of superior mesenteric artery (SMA), celiac trunk (CT), inferior vena cava (IVC), superior mesenteric vein (SMV), and differences in CT HU (Delta HU) of the bowel wall before and after intravenous contrast media (ICM) administration were correlated to the patients' outcome using ANOVA test. Receiver operating characteristic (ROC) curves were elaborated after a binary logistic regression was performed.

RESULTS

Increased number and diameter of vessels, bowel wall thickening, and hypervascularity were more frequent in patients with good prognosis. Conversely, pale mesentery, paper thin, hypovascularity, and aeroportia were more frequent in patients with bad prognosis. A significant correlation between diameters of SMA, CT, IVC, IMA, and SMV and outcome was found at univariate analysis. Also Delta HU resulted to be correlated with the outcome. At multivariate analysis only IVC and Delta HU were significant (p = 0.038 and 0.01) and the combined AUC resulted in 0.806 (CI 0.708-0.903).

CONCLUSION

Dichotomous signs of reperfusion and quantitative CT parameters can predict the outcome of patients with NOMI. In particular the combination of IVC diameter and Delta HU of bowel wall allows to predict the prognosis with the highest accuracy.

Relationship of superior mesenteric artery thrombus density with transmural intestinal necrosis on multidetector computed tomography in acute mesenteric ischemia

Background

Acute arterial occlusive mesenteric ischemia with transmural intestinal necrosis (TIN) is a fatal disease, which is difficult to diagnose on multidetector computed tomography (MDCT). The aim of the present study was to determine the relationship of superior mesenteric artery (SMA) thrombus density with TIN on MDCT in patients with acute mesenteric ischemia (AMI) due to SMA thromboembolism.

Methods

In this retrospective study, 33 patients who underwent abdominal MDCT and angiography for AMI due to SMA thromboembolism were divided into two groups: the AMI with TIN group and the AMI without TIN group. We analyzed the relationships of clinical characteristics, qualitative MDCT signs, and SMA thrombus density with TIN. The SMA thrombus density was measured on non-contrast MDCT. Univariate and multivariate analyses were performed to determine the risk factors for predicting TIN. The diagnostic performances of risk factors were evaluated by receiver-operating characteristic (ROC) curve analysis.

Results

Of the patients with AMI enrolled in this study, 33.3% (11/33) were diagnosed with TIN. Peritonitis (P=0.042), bowel wall thinning (P=0.033), and pneumatosis/portomesenteric gas (P=0.010) were significantly associated with TIN. AMI patients with TIN exhibited a higher SMA thrombus density than AMI patients without TIN [41.2±6.1 vs. 34.2±3.0 Hounsfield unit (HU), P=0.003]. Multivariate analysis showed that SMA thrombus density was an independent predictor of TIN [P=0.044, hazard ratio (HR): 1.82, 95% confidence interval (CI): 1.02-3.25]. For diagnosing AMI with TIN, the area under the ROC curve (AUC) of SMA thrombus density (0.83) was larger than those of peritonitis (0.68), bowel wall thinning (0.66), and pneumatosis/portomesenteric gas (0.71).

Conclusions

In patients with AMI, erythrocyte-rich thrombus blocking the SMA trunk which has a higher density on MDCT is prone to the occurrence of TIN compared with erythrocyte-scarce thrombus with a lower density. SMA thrombus density could be an independent risk factor for TIN in patients with AMI due to SMA thromboembolism.

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.

A clinical approach to acute mesenteric ischemia

PURPOSE OF REVIEW

To summarize current evidence on acute mesenteric ischemia (AMI) in critically ill patients, addressing pathophysiology, definition, diagnosis and management.

RECENT FINDINGS

A few recent studies showed that a multidiscipliary approach in specialized centers can improve the outcome of AMI. Such approach incorporates current knowledge in pathophysiology, early diagnosis with triphasic computed tomography (CT)-angiography, immediate endovascular or surgical restoration of mesenteric perfusion, and damage control surgery if transmural bowel infarction is present. No specific biomarkers are available to detect early mucosal injury in clinical setting. Nonocclusive mesenteric ischemia presents particular challenges, as the diagnosis based on CT-findings as well as vascular management is more difficult; some recent evidence suggests a possible role of potentially treatable stenosis of superior mesenteric artery and beneficial effect of vasodilator therapy (intravenous or local intra-arterial). Medical management of AMI is supportive, including aiming of euvolemia and balanced systemic oxygen demand/delivery. Enteral nutrition should be withheld during ongoing ischemia-reperfusion injury and be started at low rate after revascularization of the (remaining) bowel is convincingly achieved.

SUMMARY

Clinical suspicion leading to tri-phasic CT-angiography is a mainstay for diagnosis. Diagnosis of nonocclusive mesenteric ischemia and early intestinal injury remains challenging. Multidisciplinary team effort may improve the outcome of AMI.

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.

Bowel wall thickening on computed tomography scan: Inter-observer agreement and correlation with endoscopic findings

BACKGROUND AND STUDY AIMS

Bowel wall thickening (BWT) on computed tomography (CT) has been frequently reported by radiologists. There are no clear guidelines regarding the level of thickening that is correlated with definite pathology. Radiologists usually rely on their overall subjective impression, and studies on inter-observer agreement (IOA) are lacking. This study evaluated IOA concerning BWT found on abdominal CT and identified the corresponding findings on endoscopy.

PATIENTS AND METHODS

Reports of abdominal CTs performed between January 2000 and December 2015 containing the term 'thickening' were retrieved from the radiology department database. Corresponding patients who later underwent endoscopy were included. IOA concerning BWT was evaluated using a randomly mixed sample of 80 patients with normal findings or pathological BWT on endoscopy. A search for predictive factors for the subsequent finding of malignancy on endoscopy was performed using multivariate analysis.

RESULTS

During the study period, 6142 CT scans described thickening, equivalent to a BWT prevalence of 13.7%. Ninety-one patients (mean age, 58 years) were included in the analysis. Thickening was found most commonly in the stomach (38.5%), followed by the rectum (22%) and small intestine (14%). Twenty-seven patients (29.7%) exhibited diffuse BWT, whereas 64 patients showed localised BWT (70.3%). Biopsy was performed for 64 of 91 patients with endoscopies. Among these patients, 8.8% exhibited normal findings, whereas inflammation and malignancy were discovered in 25 and 51.6% of patients, respectively, with a positive predictive value for malignancy of 0.36. The IOA concerning CT for predicting significantly pathological BWT was moderate (mean κ = 0.6). A strong association was evident between the presence of lymph nodes on CT and the presence of neoplastic lesions.

CONCLUSION

Our study strongly recommends endoscopic follow-up of patients exhibiting BWT irrespective of the thickening location, especially if it is associated with lymphadenopathy. IOA between radiologists was moderate.

Non-occlusive Mesenteric Ischemia as a Fatal Complication in Acute Pancreatitis: A Brief Radiological Comment

Non-occlusive mesenteric ischemia (NOMI) is the result of the reduction of mesenteric blood supply, due to mesenteric arterial vasoconstriction secondary to hypotension in cases of shock, septicemia, dehydration, heart surgery, or major abdominal surgery. NOMI represents a complex and often misdiagnosed syndrome. Imaging, and in particular CT, has a remarkable importance in NOMI, and despite its complexity, it could allow an early diagnosis and an improved management resulting in life-threatening therapeutic approaches, much better than in the past, provided it is correctly performed and interpreted by experienced radiologists.

Non-occlusive mesenteric ischemia: two case reports and a short review of the literature

INTRODUCTION

Non-occlusive mesenteric ischemia (NOMI) is an infrequent cause of acute mesenteric ischemia with atypical symptoms and a high mortality.

PATIENTS AND METHODS

We report two cases of NOMI characterized by their difference in etiology, treatment and outcome.

RESULTS

In the first case, the patient developed NOMI after septic shock, she was successfully treated with surgery. The second patient experienced two episodes of cardiac arrest followed by NOMI. He received only supportive care and died shortly after. We present a short review of the literature, discussing epidemiology, pathophysiology, clinical presentations, diagnosis and management of NOMI.

CONCLUSION

NOMI is a rare disease with a difficult diagnosis. Early recognition and treatment with supportive therapy, vasodilator drugs and possibly surgery can significantly lower mortality.

Use of indocyanine green fluorescence imaging to determine the area of bowel resection in non-occlusive mesenteric ischemia: A case report

•

In cases of NOMI, it is difficult to determine the area of bowel resection.

•

Using ICG fluorescence imaging, we can evaluate ischemia of the intestine.

•

We adeptly resected the ischemic intestine in NOMI using ICG fluorescence imaging.

Introduction

Non-occlusive mesenteric ischemia (NOMI) is a type of acute intestinal ischemia, and its associated mortality is very high. In laparotomy of NOMI, we often have difficulty determining the area of bowel resection. We herein describe a case in which we detected the area of bowel resection using indocyanine green (ICG) fluorescence imaging.

Presentation of the case

An 89-year-old man diagnosed as having advanced gastric cancer underwent distal gastrectomy. On the night of postoperative day 4, he strongly complained of distention of the abdomen. The laboratory data indicated severe metabolic acidosis and dehydration. The abdominal computed tomography scan showed a dilated small bowel, but there were no specific signs suggestive of bowel necrosis. We suspected NOMI and decided to perform emergency laparotomy because we could not exclude the possibility of bowel necrosis. During the operation, we could not detect the necrotic bowel macroscopically. After injecting 2.5 mg of ICG, the ischemic area of the bowel became visible as a region with poor fluorescence emission using the Photodynamic Eye™ (Hamamatsu Photonics K.K.). We resected the ischemic bowel and performed anastomosis. We confirmed that he was alive at 4 months after the operation of NOMI.

Conclusion

Intraoperative ICG fluorescence imaging makes it possible to detect necrotic intestine that cannot be found with the naked eye. By using this method, planned reoperation to find any newly developed necrotic intestine might be unnecessary. Intraoperative ICG fluorescence imaging is useful for defining the area of ischemic bowel in a patient with NOMI.

Acute mesenteric ischemia: guidelines of the World Society of Emergency Surgery: a brief radiological commentary

The aim of this letter is to report some deeper explanations regarding the role of imaging in acute mesenteric ischemia.

The correlation between some computed tomography findings and the cause of ischemia as well as other main factors that could condition the computed tomography appearance of this critical issue is also discussed.

The role of multislice computed tomography (MSCT) angiography in the diagnosis and therapy of non-occlusive mesenteric ischemia (NOMI): Could MSCT replace DSA in diagnosis?

Objectives

Evaluation of multislice-CT (MSCT) during diagnosis and therapeutic decision-making in patients with suspected non-occlusive mesenteric ischemia (NOMI).

Methods

Retrospective, institutional review board-approved study of 30 patients (20 men, 10 women, mean age 64.6±14.2 years, range 24–87 years) undergoing biphasic abdominal MSCT followed by digital subtraction angiography (DSA) due to suspected NOMI. MSCT and DSA were qualitatively and quantitatively evaluated independently by two radiologists with respect to the possible diagnosis of NOMI. MSCT analysis included quantitative measurements, qualitative evaluation of contrast enhancement and assessment of secondary findings (bowel wall thickening, hypo-enhancement, intestinal pneumatosis). MSCT diagnosis and secondary findings were compared against DSA diagnosis.

Results

NOMI was diagnosed in a total of n = 28 patients. No differences were found when comparing the R1-rated MSCT diagnosis (p = 0.09) to the “gold standard”, while MSCT diagnosis was slightly inferior with R2 (p = 0.02). With R1, vessel-associated parameters revealed the best correlation, i.e. qualitative vessel width (r = -0.39;p = 0.03) and vessel contrast (r = 0.45;p = 0.01). Moderate correlations were found for quantitative vessel diameters in the middle segments (r = -0.48,p = 0.01), increasing to almost high correlations in the distal (r = -0.66;p<0.00001) superior mesenteric artery (SMA) segments. No significant correlation was apparent from secondary findings.

Conclusions

MSCT is an appropriate non-invasive method for diagnosing NOMI and leads to adequate and immediate therapeutic stratification.

Imaging of Oncologic Emergencies

Oncologic emergencies can be either the result of the primary tumor, its metastasis, a paraneoplastic syndrome or reaction to the chemotherapy. Imaging plays a crucial role in ensuring a prompt diagnosis as well as assisting in the therapeutic management. In this article, we discuss the common thoracic and abdominal oncological emergencies that may be encountered in an emergency department.

Diagnostic value of arterial blood gas lactate concentration in the different forms of mesenteric ischemia

PURPOSE

The role of serum lactate measurement in patients with intestinal ischemia still remains unclear. The aim of this study was to prospectively evaluate the diagnostic performance of arterial blood gas lactate concentrations in the patients with acute mesenteric ischemia and its different forms.

METHODS

All the patients reporting abdominal pain associated with risk factors for mesenteric ischemia underwent arterial blood gas and contrast enhanced abdominal computer tomography (CT).

RESULTS

At CT, 201 patients (70.7%) showed a nonischemic disease (group 1) and 83 patients (29.2%) showed findings of mesenteric ischemia. Out of these, 35 patients (42.1%) showed bowel ischemia secondary to non vascular causes (group 2) and 48 (57.8%) had a vascular intestinal ischemia (group 3). Out of these, 20 showed small bowel arterial occlusion (group 3a), 13 a small bowel nonocclusive ischemia (group 3b), 7 a venous small bowel occlusion (group 3c) and 8 showed isolated colonic ischemia (group 3d). The median lactate serum level was significantly higher in patients with vascular ischemia if compared with patients with nonischemic disease and secondary mesenteric ischemia (p < 0.0001; Kruskal-Wallis test). The areas under ROC curves for the lactate serum levels in the groups 2, 3, 3a, 3b, 3c and 3d were, respectively, 0.61, 0.85, 0.93, 0.93, 0.68 and 0.67.

CONCLUSIONS

Arterial blood gas lactate levels seem to show good diagnostic accuracy in diagnosing small bowel arterial and nonocclusive ischemia and poor accuracy in diagnosing secondary mesenteric ischemia, small bowel venous ischemia and ischemic colitis.