18 n APPLIED RADIOLOGY © www.appliedradiology.com January–February 2021 AN OVERVIEW OF ACUTE MESENTERIC ISCHEMIA SA-CME ischemia, 8 the most common and read- ily recognized signs detailed above, in- cluding bowel-wall thickening, bowel dilatation, mesenteric stranding, and fluid, remain nonspecific. Conversely, bowel-wall hypoenhancement, the CT sign with the highest specificity (93– 100%), is not as easily recognized. 22-26 Difficulty recognizing hypo-enhance- ment may be technique related; eg, the use of low energy levels, low volume/ concentration of contrast agent, inad- equate delay time or case related, as in the presence of intramural hemorrhage with high attenuation of the bowel wall on unenhanced CT or luminal disten- tion with thinned bowel wall. In recent years, strides made by du- al-energy CT (DECT) technology toward improved recognition of differ- ential bowel-wall enhancement have garnered interest. 16 DECT has been shown to help identify such differ- ences more readily than conventional MDCT. 16,27 However, DECT is not widely available and remains in its in- fancy with respect to clinical application. Further studies are required to consoli- date the degree of improved performance and specificity for bowel-wall hypoen- hancement detection with DECT. Conclusion Acute mesenteric ischemia is a rare but life-threatening condition that re- quires timely recognition and interven- tion. The role of radiologists is pivotal to early identification of AMI; hence, considering AMI as a differential diag- nosis when protocolling and identifying the subtle image findings detailed in this review remains vital to delivering the best patient care and outcomes. REFERENCES 1 Stoney RJ, Cunningham CG. Acute mesenteric ischemia. Surgery. 1993; 114:489-490. 2. Adaba F, Askari A, Dastur J et al. Mortality after acute primary mesenteric infarction: a systematic review and meta-analysis of observational studies. Colorectal disease: the official journal of the Associ- ation of Coloproctology of Great Britain and Ireland. 2015; 17:566-577. 3. Kanasaki S, Furukawa A, Fumoto K et al. Acute Mesenteric Ischemia: Multidetector CT Findings and Endovascular Management. Radiograph- ics.2018; 38:945-961. 4. McKinsey JF, Gewertz BL. Acute mesenteric ischemia. The Surgical clinics of North America. 1997; 77:307-318. 5. Cappell MS. Intestinal (mesenteric) vasculopa- thy. I. Acute superior mesenteric arteriopathy and venopathy. Gastroenterology Clinics of North Amer- ica. 1998; 27:783-825, vi. 6. Reinus JF, Brandt LJ, Boley SJ. Ischemic dis- eases of the bowel. Gastroenterology Clinics of North America. 1990; 19:319-343. 7. Acosta S, Ogren M, Sternby NH et al. Clinical implications for the management of acute thrombo- embolic occlusion of the superior mesenteric artery: autopsy findings in 213 patients. Ann Surg. 2005; 241:516-522. 8. Menke J. Diagnostic accuracy of multidetector CT in acute mesenteric ischemia: systematic review and meta-analysis. Radiology. 2010; 256:93-101. 9. Boley SJ, Frieber W, Winslow PR, al e. Circula- tory responses to acute reduction of superior mes- enteric arterial flow. Physiologist. 1969; 12:180. 10. Granger DN, Rutili G, McCord JM. Superoxide radicals in feline intestinal ischemia. Gastroenterol- ogy. 1981; 81:22-29. 11. Zimmerman BJ, Granger DN. Reperfusion injury. The Surgical clinics of North America. 1992; 72:65-83. 12. Perry RJ, Martin MJ, Eckert MJ et al. Colonic ischemia complicating open vs endovascular abdominal aortic aneurysm repair. J Vasc Surg. 2008; 48:272-277. 13. John AS, Tuerff SD, Kerstein MD. Nonocclusive mesenteric infarction in hemodialysis patients. J Am Coll Surg. 2000; 190:84-88. 14. Brandt LJ, Feuerstadt P, Longstreth GF, Boley SJ. ACG clinical guideline: epidemiology, risk factors, patterns of presentation, diagnosis, and management of colon ischemia (CI). Am J Gastro- enterol. 2015; 110:18-44; quiz 45. 15. Abu-Daff S, Abu-Daff N, Al-Shahed M. Mes- enteric venous thrombosis and factors associated with mortality: a statistical analysis with five-year fol- low-up. J Gastro Surg. 2009; 13:1245-1250. 16. Lourenco PDM, Rawski R, Mohammed MF et al. Dual-Energy CT Iodine Mapping and 40-keV Monoenergetic Applications in the Diagnosis of Acute Bowel Ischemia. AJR. Am J Roentgenol. 2018; 211:564-570. 17. Firetto MC, Lemos AA, Marini A et al. Acute bowel ischemia: analysis of diagnostic error by overlooked findings at MDCT angiography. Emer- gency Radiology. 2013; 20:139-147. 18. Yasuhara H, Niwa H, Takenoue T, Naka S. Factors influencing mortality of acute intestinal infarction associated with SIRS. Hepato-gastroen- terology. 2005; 52:1474-1478. 19. Karkkainen JM, Lehtimaki TT, Saari P et al. Endovascular Therapy as a Primary Revasculariza- tion Modality in Acute Mesenteric Ischemia. Cardio- vasc Intervent Radiol. 2015; 38:1119-1129. 20. Tilsed JV, Casamassima A, Kurihara H et al. ESTES guidelines: acute mesenteric ischaemia. Eur J Trauma Emerg Surg. 2016; 42:253-270. 21. Acosta S, Bjorck M. Modern treatment of acute mesenteric ischaemia. Brit J Surg. 2014; 101: e100-108. 22. Taourel PG, Deneuville M, Pradel JA et al. Acute mesenteric ischemia: diagnosis with contrast-enhanced CT. Radiology. 1996; 199: 632-636. 23. Zalcman M, Sy M, Donckier V et al. Helical CT signs in the diagnosis of intestinal ischemia in small- bowel obstruction. AJR. Am J Roentgenol. 2000; 175:1601-1607. 24. Kirkpatrick ID, Kroeker MA, Greenberg HM. Biphasic CT with mesenteric CT angiography in the evaluation of acute mesenteric ischemia: initial experience. Radiology. 2003; 229:91-98. 25. Sheedy SP, Earnest Ft, Fletcher JG et al. CT of small-bowel ischemia associated with obstruction in emergency department patients: diagnostic perfor- mance evaluation. Radiology. 2006; 241:729-736. 26. Geffroy Y, Boulay-Coletta I, Julles MC et al. Increased unenhanced bowel-wall attenuation at multidetector CT is highly specific of ischemia com- plicating small-bowel obstruction. Radiology. 2014; 270:159-167. 27. Potretzke TA, Brace CL, Lubner MG et al. Early small-bowel ischemia: dual-energy CT improves conspicuity compared with conventional CT in a swine model. Radiology. 2015; 275:119-126.