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

Dual-energy CT late arterial phase iodine maps for the diagnosis of acute non-occlusive mesenteric ischemia

PURPOSE

To evaluate the diagnostic accuracy of dual-energy CT (DECT) iodine maps in comparison to conventional CT series for the assessment of non-occlusive mesenteric ischemia (NOMI).

MATERIAL AND METHODS

We evaluated data from 142 patients (72 men; 50.7%) who underwent DECT between 2018 and 2022, with surgically confirmed diagnosis of NOMI. One board-certified radiologist performed region of interest (ROI) measurements in bowel segments on late arterial (LA) and portal venous (PV) phase DECT iodine maps as well as LA conventional series, in both ischemic and non-ischemic bowel loops, using surgical reports as reference standard, and in a control group of 97 patients. Intra- and inter-reader agreement with a second board-certified radiologist was also evaluated. Receiver operating characteristic (ROC) curve analysis was performed to calculate the optimal threshold for discriminating ischemic from non-ischemic bowel segments. Subjective image rating of LA and PV iodine maps was performed.

RESULTS

DECT-based iodine concentration (IC) measurements showed significant differences in LA phase iodine maps between ischemic (median:0.72; IQR 0.52-0.91 mg/mL) and non-ischemic bowel loops (5.16; IQR 3.45-6.31 mg/ml) (P <.0001). IC quantification on LA phase revealed an AUC of 0.966 for the assessment of acute bowel ischemia, significantly higher compared to both IC quantification based on PV phase (0.951) and attenuation values evaluated on LA conventional CT series (0.828). Excellent intra-observer and strong inter-observer agreements were observed for the quantification of iodine concentration. Conversely, weak inter-observer agreement was noted for conventional HU assessments. The optimal LA phase-based IC threshold for assessing bowel ischemia was 1.34 mg/mL, yielding a sensitivity of 100% and specificity of 96.48%.

CONCLUSION

Iodine maps based on LA phase significantly improve the diagnostic accuracy for the assessment of NOMI compared to conventional CT series and PV phase iodine maps.

Revascularization Strategies for Acute and Chronic Mesenteric Ischemia: A Narrative Review

Mesenteric ischemia is a challenging condition characterized by insufficient blood perfusion to the mesentery and, consequently, intestinal tissues that continues to perplex clinicians. Despite its low prevalence, the condition's variable clinical presentation and elusive radiographic diagnosis can delay life-saving interventions in the acute setting and deteriorate the quality of life of patients when left undiagnosed or misdiagnosed.

PURPOSE

Review and summarize recent diagnostic updates and emergent intervention strategies for acute and chronic mesenteric ischemia.

METHODS

A narrative review of all relevant studies from January 2022 through September 2023.

RESULTS

A total of 11 studies from MEDLINE, supplemented with 44 studies from Google Scholar, were included in the review.

CONCLUSIONS

Both acute and chronic mesenteric ischemia propose diagnostic and therapeutic challenges for interventionalists. Computed tomographic angiography remains the diagnostic modality of choice for both. Open surgical intervention remains the gold standard for acute mesenteric ischemia, while endovascular techniques are preferred for chronic mesenteric ischemia.

Stapled Anastomosis Versus Hand-Sewn Anastomosis With Mucosectomy for Ileal Pouch-Anal Anastomosis: A Systematic Review and Meta-analysis of Postoperative Outcomes, Functional Outcomes, and Oncological Safety

PURPOSE

This systematic review and meta-analysis aimed to compare outcomes between stapled ileal pouch-anal anastomosis (IPAA) and hand-sewn IPAA with mucosectomy in cases of ulcerative colitis and familial adenomatous polyposis.

METHODS

This systematic review and meta-analysis was performed according to the Preferred Reporting Items for Systematic Review and Meta-analysis) guidelines 2020 and AMSTAR 2 (Assessing the methodological quality of systematic reviews) guidelines. We included randomized clinical trials (RCTs) and controlled clinical trials (CCTs). Subgroup analysis was performed according to the indication for surgery.

RESULTS

The bibliographic research yielded 31 trials: 3 RCTs, 5 prospective clinical trials, and 24 CCTs including 8872 patients: 4871 patients in the stapled group and 4038 in the hand-sewn group. Regarding postoperative outcomes, the stapled group had a lower rate of anastomotic stricture, small bowel obstruction, and ileal pouch failure. There were no differences between the 2 groups in terms of operative time, anastomotic leak, pelvic sepsis, pouchitis, or hospital stay. For functional outcomes, the stapled group was associated with greater outcomes in terms of seepage per day and by night, pad use, night incontinence, resting pressure, and squeeze pressure. There were no differences in stool Frequency per 24h, stool frequency at night, antidiarrheal medication, sexual impotence, or length of the high-pressure zone. There was no difference between the 2 groups in terms of dysplasia and neoplasia.

CONCLUSIONS

Compared to hand-sewn anastomosis, stapled ileoanal anastomosis leads to a large reduction in anastomotic stricture, small bowel obstruction, ileal pouch failure, seepage by day and night, pad use, and night incontinence. This may ensure a higher resting pressure and squeeze pressure in manometry evaluation.

PROTOCOL REGISTRATION

The protocol was registered at PROSPERO under CRD 42022379880.

Risk factors for postoperative disseminated intravascular coagulation in surgical patients with non-occlusive mesenteric ischemia

PURPOSE

The prognostic impact of disseminated intravascular coagulation (DIC) in surgical patients with non-occlusive mesenteric ischemia (NOMI) is unclear. This study aimed to confirm the association between postoperative DIC and prognosis and to identify preoperative risk factors associated with postoperative DIC.

METHODS

This retrospective study included 52 patients who underwent emergency surgery for NOMI between January 2012 and March 2022. Kaplan-Meier curve analysis with the log-rank test was used to compare 30-day survival and hospital survival between patients with and without postoperative DIC. In addition, univariable and multivariable logistic regression analyses were performed to identify the preoperative risk factors for postoperative DIC.

RESULTS

The 30-day and hospital mortality rates were 30.8% and 36.5%, respectively, and the incidence rate of DIC was 51.9%. Compared to patients without DIC, patients with DIC showed significantly lower rates of 30-day survival (41.5% vs 96%, log-rank P < 0.001) and hospital survival (30.2% vs 86.4%, log-rank, P < 0.001). Logistic regression analyses showed that the Japanese Association for Acute Medicine (JAAM) DIC score (OR = 2.697; 95% CI, 1.408-5.169; P = 0.003) and Sequential Organ Failure Assessment (SOFA) score (OR = 1.511; 95% CI, 1.111-2.055; P = 0.009) were independent risk factors for postoperative DIC in surgical patients with NOMI.

CONCLUSION

The development of postoperative DIC is a significant prognostic factor for 30-day and hospital mortalities in surgical patients with NOMI. In addition, the JAAM DIC score and SOFA score have a high discriminative ability for predicting the development of postoperative DIC.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

KEY POINTS

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

An Update on Acute Mesenteric Ischemia

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

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.

Abdominal atherosclerosis is not a risk factor of nonocclusive mesenteric ischemia among critically ill patients: a propensity matching study

BACKGROUND

Although risk factors of occlusive acute mesenteric ischemia are well known, triggering factors of nonocclusive mesenteric ischemia (NOMI) remain unclear. Alongside to the known risk factors for NOMI, the role of atherosclerosis is not fully elucidated. The purpose of our study was to evaluate whether abdominal atherosclerosis is a risk factor for NOMI.

METHODS

From January 2018 to December 2021, all consecutive patients admitted to the intensive care unit who underwent contrast-enhanced CT for suspicion of NOMI were evaluated for inclusion. Clinical and biological data at the time of the CT scan were retrospectively extracted from medical charts and reviewed by a single radiologist. The cohorts were matched by a 1:1 propensity score based on the patient clinical, biological data, and abdominal CT features associated with NOMI. Noncontrast CT acquisitions were used to calculate calcium scores of the abdominal aorta, celiac trunk, superior mesenteric artery (SMA), and common iliac artery according to the Agatston method. Analyses were performed before and after propensity score matching.

RESULTS

Among the 165 critically ill patients included, 59 (36%) had NOMI. Before matching analysis, the SMA and total abdominal Agatston calcium scores were not different between patients without and with NOMI (52.00 [IQR = 0, 473] vs. 137.00 [IQR = 0, 259], P = 0.857, respectively, and 7253 [IQR = 1220, 21738] versus 5802 [IQR = 2075, 15,084]; P = 0.723). The results were similar after matching 38 patients with NOMI and 38 without: 153 [IQR = 0, 665] versus 85 [IQR = 0, 240] (P = 0.312) for the SMA calcium score, and 7915 [IQR = 1812, 21561] versus 4139 [IQR = 1440, 9858] (P = 0.170) for the total abdominal Agatston calcium score.

CONCLUSION

Our results suggest that atherosclerosis is not a risk factor for NOMI in critically ill patients.