Many faces of acute bowel ischemia: overview of radiologic staging

The target sign: a significant CT sign for predicting small-bowel ischemia and necrosis

OBJECTIVE

To investigate the correlation between changes in the thickness and density of diseased small-bowel wall and small-bowel ischemia and necrosis (SBN) on CT imaging when small-bowel obstruction (SBO) occurs.

METHODS

We retrospectively analyzed 186 patients with SBO in our hospital from March 2020 to June 2023. The patients were divided into simple SBO (control group) and SBN (case group) groups. We used logistic regression analysis, the chi-square test, and Fisher's exact test to analyze the correlation between the changes in the thickness and density of the diseased intestinal wall and the SBN. A receiver operating characteristic (ROC) curve was used to calculate the accuracy of the multivariate analysis.

RESULTS

Of the 186 patients with SBO, 98 (52.7%) had simple SBO, 88 (47.3%) had SBN, and the rate of SBN was 47.3% (88/186). Multivariate regression analysis revealed that six CT findings were significantly correlated with SBN (p < 0.05), namely, thickening of the diseased intestinal wall with the target sign (OR = 21.615), thinning of the diseased intestinal wall (OR = 48.106), increase in the diseased intestinal wall density (OR = 13.696), mesenteric effusion (OR = 21.635), decrease in the diseased intestinal wall enhancement on enhanced scanning (OR = 41.662), and increase in the diseased intestinal wall enhancement on enhanced scanning (OR = 15.488). The AUC of the multivariate analysis reached 0.987 (95% CI 0.974-0.999). Specifically, the target sign was easily recognizable on CT images and was a significant CT finding for predicting SBN.

CONCLUSION

We identified 6 CT findings that were significantly associated with SBN, and may be helpful for clinical treatment.

Mesenteric ischemia in the acute care setting

ABSTRACT

Mesenteric ischemia is a group of disorders requiring prompt identification, supportive care, and treatment. Chronic mesenteric ischemia can develop into acute mesenteric ischemia, which has high mortality. Acute mesenteric ischemia can be occlusive (caused by arterial embolism, arterial thrombosis, or mesenteric venous thrombosis) or nonocclusive, with treatment depending on the underlying cause.

Iodine density mapping for the diagnosis of acute bowel ischemia using fast kV-switching dual-energy CT

PURPOSE

To evaluate the diagnostic capabilities of a supplementary color ramped iodine density map compared to virtual monoenergetic images (VMIs) at 74 keV in the diagnosis of acute bowel ischemia (ABI).

METHODS

Data for this study were prospectively gathered and retrospectively evaluated. Patients referred to the Department of Diagnostic Radiology between October 2020 and August 2022 on the suspicion of ABI and underwent surgery < 12 h following fast kV-switching venous phase abdominal dual-energy CT (DECT) were consecutively included. Images were evaluated by two board-certified radiologists and two radiology residents. First round included only 74 keV VMIs resembling conventional 120 kVp images, and the second round included a supplementary iodine density map. Readers were asked to register presence of ABI as well as their confidence in their diagnosis based on a 5-point Likert scale. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for each observer with the surgical findings as the gold-standard. McNemar's and Wilcoxon signed-rank test were used to compare registrations and diagnostic confidence across assessment rounds.

RESULTS

A total of 29 patients resulting in 31 DECT scans were included. Fourteen cases of ischemic/necrotic bowel were reported following surgery. Sensitivity and NPV were decreased with the use of supplementary iodine map images compared to 120 kVp-like images without supplementary iodine map images for three of four observers (round 1 range: 71.4-92.9% and 78.0-94.8%; round 2 range: 57.1-78.6% and 70.1-83.3%, respectively), while specificity and PPV were increased for three of four observers (round 1 range: 64.7-94.1% and 67.4-93.1%; round 2 range: 88.2-94.1% and 73.8-91.1%, respectively). However, no significant difference in ABI diagnosis or diagnostic confidence was found (p-value range: 0.07-1.00 and 0.23-0.58, respectively).

CONCLUSION

No significant difference for the diagnosis of ABI was found using supplementary iodine mapping. Our study may suggest a trend of increased specificity and decreased sensitivity, hence, the use of supplementary iodine mapping should be carefully considered.

Mesenteric ischemia in the acute care setting

ABSTRACT

Mesenteric ischemia is a group of disorders requiring prompt identification, supportive care, and treatment. Chronic mesenteric ischemia can develop into acute mesenteric ischemia, which has high mortality. Acute mesenteric ischemia can be occlusive (caused by arterial embolism, arterial thrombosis, or mesenteric venous thrombosis) or nonocclusive, with treatment depending on the underlying cause.

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.

MRI for the Detection of Small Bowel Ischemic Injury in Arterial Acute Mesenteric Ischemia: Preclinical Study in a Porcine Model

BACKGROUND

MRI is the reference for the diagnosis of arterial cerebral ischemia, but its role in acute mesenteric ischemia (AMI) is poorly known.

PURPOSE

To assess MRI detection of early ischemic bowel lesions in a porcine model of arterial AMI.

STUDY TYPE

Prospective/cohort.

ANIMAL MODEL

Porcine model of arterial AMI obtained by embolization of the superior mesenteric artery (seven pigs).

FIELD STRENGTH/SEQUENCE

A 5-T. T1 gradient-echo-weighted-imaging (WI), half-Fourier-acquisition-single-shot-turbo-spin-echo, T2 turbo-spin-echo, true-fast-imaging-with-steady-precession (True-FISP), diffusion-weighted-echo-planar (DWI).

ASSESSMENT

T1-WI, T2-WI, and DWI were performed before and continuously after embolization for 6 hours. The signal intensity (SI) of the ischemic bowel was assessed visually and quantitatively on all sequences. The apparent diffusion coefficient (ADC) was assessed.

STATISTICAL TESTS

Paired Student's t-test or Mann-Whitney U-test, significance at P < 0.05.

RESULTS

One pig died from non-AMI-related causes. The remaining pigs underwent a median 5 h53 (range 1 h24-6 h01) of ischemia. Visually, the ischemic bowel showed signal hyperintensity on DWI-b800 after a median 85 (57-276) minutes compared to the nonischemic bowel. DWI-b800 SI significantly increased after 2 hours (+19%) and the ADC significant decrease within the first hour (-31%). The ischemic bowel was hyperintense on precontrast T1-WI after a median 87 (70-171) minutes with no significant quantitative changes over time (P = 0.46-0.93). The ischemic bowel was hyperintense on T2-WI in three pigs with a significant SI increase on True-FISP after 1 and 2 hours.

DATA CONCLUSION

Changes in SI and ADC can be seen early after the onset of arterial AMI with DWI. The value of T2-WI appears to be limited.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 2.

Involvement of transverse mesocolon is associated with development of colonic fistula in patients with acute necrotizing pancreatitis

BACKGROUND

Involvement of transverse mesocolon (TM) during acute necrotizing pancreatitis(ANP) indicates that inflammation has spread from retroperitoneal space to peritoneum. Nevertheless, the impact of TM involvement, as confirmed by contrast-enhanced computed tomography (CECT), on local complications and clinical outcomes was poorly investigated.

PURPOSE

This study aimed to explore the association between CECT-diagnosed TM involvement and the development of colonic fistula in a cohort of ANP patients.

METHODS

This is a single-center, retrospective cohort study involving ANP patients admitted from January 2020 to December 2020. TM involvement was diagnosed by two experienced radiologists. The study subjects were enrolled consecutively and divided into two groups: TM involvement and non-TM involvement. The primary outcome was colonic fistula during the index admission. Clinical outcomes were compared between the two groups, and the association between the TM involvement and the development of colonic fistula was assessed using multivariable analysis to adjust for baseline unbalances.

RESULTS

A total of 180 patients with ANP were enrolled, and 86 (47.8%) patients had TM involvement. The incidence of the colonic fistula is significantly higher in patients with TM involvement (16.3% vs. 5.3%;p = 0.017). Moreover, the length of hospital stay was 24(13,68) days in patients with TM involvement and 15(7,31) days in those not (p = 0.001). Analysis of multivariable logistic regression revealed that TM involvement is an independent risk factor for the development of colonic fistula (odds ratio: 10.253, 95% CI: 2.206-47.650, p = 0.003).

CONCLUSION

TM involvement in ANP patients is associated with development of colonic fistula in ANP patients.

[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.

Acute mesenteric ischaemia

PURPOSE OF REVIEW

To summarize the recent evidence on acute mesenteric ischaemia (AMI).

RECENT FINDINGS

The overall incidence of AMI is below 10/100 000 person years but increases exponentially with age. The overall mortality of AMI remains high, exceeding 50%, despite continuing progress and increasing availability of imaging and endovascular interventions. However, patients with (early) revascularization have significantly better outcomes. The majority of patients surviving the acute event are still alive at 1 year, but evidence on quality of life is scarce.Clinical suspicion of AMI is the key to timely diagnosis, with biphasic computed tomography-angiography the diagnostic method of choice. Currently, no biomarker has sufficient specificity to diagnose AMI.

SUMMARY

Improved awareness and knowledge of AMI are needed to raise the suspicion of AMI in relevant patients and thereby to achieve better outcomes.

Imaging of intestinal vasculitis focusing on MR and CT enterography: a two-way street between radiologic findings and clinical data

Diagnosis of intestinal vasculitis is often challenging due to the non-specific clinical and imaging findings. Vasculitides with gastrointestinal (GI) manifestations are rare, but their diagnosis holds immense significance as late or missed recognition can result in high mortality rates. Given the resemblance of radiologic findings with some other entities, GI vasculitis is often overlooked on small bowel studies done using computed tomography/magnetic resonance enterography (CTE/MRE). Hereon, we reviewed radiologic findings of vasculitis with gastrointestinal involvement on CTE and MRE. The variety of findings on MRE/CTE depend upon the size of the involved vessels. Signs of intestinal ischemia, e.g., mural thickening, submucosal edema, mural hyperenhancement, and restricted diffusion on diffusion-weighted imaging, are common in intestinal vasculitis. Involvement of the abdominal aorta and the major visceral arteries is presented as concentric mural thickening, transmural calcification, luminal stenosis, occlusion, aneurysmal changes, and collateral vessels. Such findings can be observed particularly in large- and medium-vessel vasculitis. The presence of extra-intestinal findings, including within the liver, kidneys, or spleen in the form of focal areas of infarction or heterogeneous enhancement due to microvascular involvement, can be another radiologic clue in diagnosis of vasculitis. The link between the clinical/laboratory findings and MRE/CTE abnormalities needs to be corresponded when it comes to the diagnosis of intestinal vasculitis.

Chronic mesenteric ischemia: causes, methods of diagnosis and treatment

Chronic mesenteric ischemia (CMI) is an urgent public health problem. The long asymptomatic course of the disease, sudden onset and an unfavorable prognosis in the absence of treatment make it necessary to pay closer attention to this pathology. There are currently two competitive treatments for CMI: surgical and endovascular revascularization. Despite numerous studies comparing these methods, the question of which one is more effective and reliable remains open. The review includes current data from clinical trials and meta-analyses demonstrating the advantages and disadvantages of both methods.

Haematological inflammatory markers for indicating ischemic bowel in patients with incarcerated abdominal wall hernias

PURPOSE

To reveal the clinical significance of preoperative haematological inflammatory markers in the diagnosis of abdominal wall hernias with strangulation.

METHODS

The data of 200 patients who underwent surgery for incarcerated hernia were retrospectively analysed. The patients were grouped into three groups; Group 1; only surgical reduction and hernia repair, Group 2; small bowel resection and Group 3; omentum resection. Age, gender, hernia type, the presence of radiological bowel obstruction and preoperative complete blood count data were obtained. Neutrophil-leukocyte ratio (NLR), lymphocyte-monocyte ratio (LMR), platelet-lymphocyte ratio (PLR), haematological inflammatory index (HII) and systemic immune-inflammation index (SII) values were calculated.

RESULTS

The study was consisted of; Group 1: 119 patients (59.5%), Group 2: 46 patients (23%) and Group 3: 35 patients (17.5%). Advanced age (p = 0.001), female gender (p = 0.036), incisional hernias (p =  < 0.001) and the presence of bowel obstruction (p =  < 0.001) were found to be statistically significant in terms of strangulation. NLR, PLR and SII values were significantly higher in Group 2 compared to Group 1, and PLR values were significantly higher in Group 2 compared with Group 3 (p < 0.05).

CONCLUSION

The preoperative elevated NLR, PLR and SII values may indicate strangulation and possible intestinal resection, in incarcerated abdominal wall hernias.