Ischaemic bowel - imaging

Imaging in acute and chronic mesenteric ischaemia

1. BOWEL ISCHEMIA DR ANUSHUYA JUNIOR RESIDENT STANLEY RADIOLOGY DEPARTMENT 24/07/19 STANLEY RADIOLOGY DEPT 1

2. CLASSIFICATION ACUTE / CHRONIC OCCLUSIVE / NON OCCLUSIVE GENERALISED / LOCALISED ARTERIAL / VENOUS 24/07/19 STANLEY RADIOLOGY DEPT 2

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4. ACUTE MESENTERIC ISCHAEMIA Mortality 60-80% The four major causes of acute mesenteric ischemia are SMA embolus (40-50% ) SMA thrombosis (20-30%) nonocclusive mesenteric ischaemia (NOMI) (25%) and mesenteric venous thrombosis (5-15%) other causes – Aortic dissection Dissection of SMA/ coeliac axis CLINICAL – Abd pain, distension and bloody diarrhoea 24/07/19 STANLEY RADIOLOGY DEPT 4

5. AMI - IMAGING Plain radiograph: Gasless abdomen- fluid filled loops from exudation, ascites Dilated bowel loops Pneumatosis intestinalis , Porto- mesentericvenous gas 24/07/19 STANLEY RADIOLOGY DEPT 5

6. AMI - IMAGING Barium enema Thumb printing Picket fencing Uncoiling of loops 24/07/19 STANLEY RADIOLOGY DEPT 6

7. AMI - IMAGING USG & DOPPLER Edematous thickened bowel wall Free fluid Air in bowel wall/portal vein Aperistaltic bowel Blunting of the increase in PSV in SMA following meal 24/07/19 STANLEY RADIOLOGY DEPT 7

8. AMI - IMAGING CT Circumferential bowel wall thickening Focal / diffuse bowel dilatation Mesenteric edema- increased attenuation of mesenteric fat Ascites Pneumatosis intestinalis Portal venous gas Pneumoperitoneum 24/07/19 STANLEY RADIOLOGY DEPT 8

9. AMI - IMAGING CECT -Enhancement pattern Diminished enhancement or Absent Increased- in venous occlusion/ shock bowel/reperfusion Delayed & persistent –delayed venous return / arteriospasm 24/07/19 STANLEY RADIOLOGY DEPT 9

10. ACUTE SMA EMBOLISM Most common cause of acute mesenteric ischemia Mc source of emboli- cardiac Most emboli lodge just beyond the origin of the middle colic artery – inferior pancreatico duodenal artery is spared The angiographic hallmark - abrupt termination of the vessel (cutoff sign). Nonocclusive emboli - visualized as filling defects in the vessel lumen. Typically, no or only a paucity of collateral vessels are present. 24/07/19 STANLEY RADIOLOGY DEPT 10

11. ACUTE SMA THROMBOSIS Typically associated with a preexisting atherosclerotic lesion. In up to 50% of cases, a history of intestinal angina is present. Symptoms - may be more insidious because of the presence of collateral circulation. Occlusion of the SMA is typically within the first 2 cm of its origin, in contrast to acute embolic occlusions, which occur more distally. 24/07/19 STANLEY RADIOLOGY DEPT 11

12. MESENTERIC VENOUS THROMBOSIS The CT appearance after venous thrombosis is generally much more impressive, as the bowel wall is usually markedly thickened , the wall can be diffusely hypointense because of edema or hyperintense because of intramural hemorrhage , the mucosa is often avidly hyperemic. The bowel can sometimes be moderately dilated, and there is typically significant mesenteric hemorrhage, edema, fluid, and fat-stranding, even in the absence of true bowel infarction . (Less marked in a rterial thrombosis) 24/07/19 STANLEY RADIOLOGY DEPT 12

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14. NON OCCLUSIVE MESENTERIC ISCHEMIA (NOMI) Mortality rate - as high as 70% . Develops during an episode of cardiogenic shock or a state of hypoperfusion in which excessive sympathetic activity results in secondary vasoconstriction of the mesenteric arteries. Watershed areas more affected. Causes: cardiogenic shock, cardiac failure , acute myocardial infarction, severe hypovolemia , trauma, renal failure with overly aggressive dialysis,or severe vasoconstriction from drugs (e.g., digitalis,cocaine ) 24/07/19 STANLEY RADIOLOGY DEPT 14

15. NOMI - IMAGING CTA : Abnormally small mesenteric arteries with visualisation of minimal branches E xtremely delayed filling of the mesenteric veins Associated bowel wall thickening and pneumatosis . 24/07/19 STANLEY RADIOLOGY DEPT 15

16. NOMI IMAGING 24/07/19 STANLEY RADIOLOGY DEPT 16

17. RARE CAUSES AORTIC DISSECTION SPONTANEOUS DISSECTION OF SMA & CELIAC A. 24/07/19 STANLEY RADIOLOGY DEPT 17

18. Bowel infarction with pneumatosis CECT  shows ascites, extensive  pneumatosis , and air within  the  mesenteric veins.  24/07/19 STANLEY RADIOLOGY DEPT 18

19. CHRONIC MESENTERIC ISCHAEMIA Abdominal angina characterized by a classic clinical triad of postprandial abdominal pain, weight loss, and food avoidance Causes- atherosclerotic, ( atleast 2/3 vessels, >70% occlusion) non atherosclerotic Fibromuscular dysplasia Median arcuate ligament syndrome Vasculitis Connective Tissue Disorders Other Rare Causes - Abdominal coarctation , neurofibromatosis, post irradiation arteritis, and idiopathic fibrosis 24/07/19 STANLEY RADIOLOGY DEPT 19

20. CMI IMAGING FEATURES Barium: Flattening of mesenteric border Pseudosacculations / pseudodiverticula in antimesenteric border Smooth strictures Atrophic valvulae Doppler : Coeliac axis PSV>200cm/sec SMA PSV> 275 CM/sec, EDV> 45 cm/ sec CT & Angiography: Presence of vascular narrowing Simultaneous presence of collateral pathways 24/07/19 STANLEY RADIOLOGY DEPT 20

21. Collaterals in Coeliac artery occlusion Pancreatico –duodenal arcade Arc of Barkow (RGE & LGE) 24/07/19 STANLEY RADIOLOGY DEPT 21

22. Collaterals in SMA /IMA occlusion Arc of Riolan MC OF SMA TO LC OF IMA Marginal a. of Drummond (T. branches of SMA & IMA) 24/07/19 STANLEY RADIOLOGY DEPT 22

23. MEDIAN ARCUATE LIGAMENT SYNDROME Extrinsic compression of the celiac artery/SMA by the central tendon of the crura of the diaphragm Smooth indentation of the superior aspect of the proximal celiac artery 24/07/19 STANLEY RADIOLOGY DEPT 23

24. Rx of AMI & CMI AMI: Surgical embolectomy or thrombectomy , together with resection of nonviable bowel CMI: Endarterectomy Bypass grafts PTA Stent placement 24/07/19 STANLEY RADIOLOGY DEPT 24

25. REVIEW QUESTIONS Water shed areas are more affected in NOMI – True / False? True NOMI is a cause of acute mesenteric ischaemia . True /False? True Features of chronic mesenteric ischaemia in Barium study? Flattening of mesenteric border Pseudosacculations / pseudodiverticula in antimesenteric border Smooth strictures Atrophic valvulae 24/07/19 STANLEY RADIOLOGY DEPT 25

26. REVIEW QUESTIONS Identify the marked vessels 24/07/19 STANLEY RADIOLOGY DEPT 26

27. REVIEW QUESTIONS 24/07/19 STANLEY RADIOLOGY DEPT 27 Diagnosis?