This document discusses imaging in bowel ischemia. It provides an overview of the anatomy of the splanchnic circulation and mesenteric arteries/veins. It then covers the pathophysiology, causes, clinical features, and imaging findings of both acute and chronic mesenteric ischemia. For imaging, it discusses the role of plain radiography, ultrasound and Doppler, CT, angiography, and MRI. It provides examples of imaging findings for different types of mesenteric ischemia and highlights how each modality can help in diagnosis.

1. IMAGING IN
BOWEL ISCHEMIA
MODERATOR : Dr. SHRIDHAR M N
PRESENTER: DR.GANESH GADAG

2. Anatomy Of Splanchnic Circulation
The splanchnic or mesenteric arteries
comprise
 Celiac artery
 Superior mesenteric artery
 Inferior mesenteric artery

7. Major collateral circuits

Pancreaticoduodenal
arcade
Celiac
artery
SMA
Arc Of Riolan
SMA
Marginal Artery Of
Drummond
IMA
IMA
SMA

10. MESENTERIC VEINS
 Superior Mesenteric Vein
 Inferior Mesenteric Vein

13. Mesenteric Ischemia

14. Mesenteric ischemia is condition
characterized by inadequate blood flow to
or from the involved mesenteric vessels
supplying a particular segment of bowel

15. PATHOPHYSIOLOGY :
ISCHEMIC INJURY DEPRIVES O2 AND NUTRITION TO
CELLULAR METABOLISM AND ITS INTACTNESS
↓
DUE TO DECREASED ARTERIAL PRESSURE DISTAL
OBSTUCTION COLLATERALS FORMED
↓
AFTER CRITICAL PERIOD,PERSISTANCE OF ISCHEMIA
VASOCONSTRICTION ↓
INCREASED ARTERIAL PRESSURE WHICH HAMPERS
COLLATERALS

16. ARTERIAL OCLUSION VENOUS OCLUSION
VASOSPASM AND SUBSEQUENT STASIS AND EDEMA
LOSS OF CELLULAR INTEGRITY
↓ ↓
INTESTINAL NECROSIS AND PERITONITIS

17. ACUTE BOWEL ISCHEMIA STAGES
STAGE I – REVERSIBLE
LIMITED TO MUCOSA ONLY
STAGE II – EXTENDS SUBMUCOSA AND
MUSCULARIS MUCOSA
STAGE III – TRANSMURAL (HIGH MORTALITY)

18. VENOUS
OCCLUSION
ARTERIAL
OCCLUSION
Non occlusive
Mesenteric ischemia

20. Causes-Acute MI
Arterial origin
 Thromboembolism
 Trauma
 Extension of
abdominal aorta
dissection
 Vasculitis
 Arterial compression
/ infiltration.
 Non Occlusive
Ischemia
VENOUS ORIGIN
 Closed loop bowel
obstruction
 Portal hypertension
 Abdominal and pelvic
inflammation
 Hypercoagulable states
 Abdominal surgery
 Renal and cardiac
disease

21. Clinical features
 Classic triad of acute ischemia includes:
• Abdominal pain (Out of proportion to clinical
signs)
• Pyrexia
• Blood in stools

22. Imaging Options
 Plain Radiograph
 Ultrasound and Doppler
 Computed tomography
 Angiography
 MRI

24. ABDOMINAL PLAIN
RADIOGRAPH
 Gas filled, dilated small bowel loops with air fluid
levels.
 Thumb printing sign (thickening of bowel wall +
valvulae (edema)
 Pneumatosis intestinalis.
 Mesenteric + portal vein gas

28. Ultrasound and Doppler
 In patients suspected of acute mesenteric
ischemia do not typically present to vascular
ultrasound due to severity of their symptoms
and urgency of condition.
 It has important role in chronic mesenteric
ischemia

29. Indirect evidence
 Rarely identification of occlusion of SMA / SMV.
 Dilated bowel loops and bowel wall thickening
 Pneumatosis intestinalis
 Air in portal venous system

31. Pneumatosis intestinalis

32. Air within the portal venous system

33. Mesenteric Vessel Doppler

34.  It is a noninvasive means with proven value in
detecting mesenteric artery stenosis and
occlusion.

35. USG & Doppler Findings
 Grey scale evaluation :
- atherosclerotic plaque or thrombus at the site of stenosis /
occlusion.
 Color Doppler :
 Luminal narrowing
 Color flow aliasing
 Reversal of flow
 Collateral vessels

36. Normal wave form patterns
 High resistance flow with low diastolic velocities
in fasting state characterize SMA & IMA.
 Low resistance flow with high end diastolic
velocities characterize celiac artery.

38. Normal velocities
Range of normal blood flow velocities in
 Celiac artery : 98 – 105 cm/sec
 SMA : 97 – 142 cm/sec
 IMA : 93 -189 cm/sec
 Widely accepted criteria are based on the
PSV measurements of mesenteric arteries

39.  Pulsed Doppler :
Elevated velocities
 PSV of > 200 cm/sec in celiac artery
 PSV of > 275 cm/sec in SMA are predictive of
stenosis of 70% or more.
 Mesenteric : Aortic ratio greater than 3 is
associated with hemodynamically significant
stenosis .

40. Aliasing artifact with high
grade velocity of 456 cm/sec
in proximal celiac artery

41. SMA stenosis with high velocity and
low velocity in post stenotic zone

42. Computed tomography

43.  CT is the primary imaging modality, and it
has been proven to be highly accurate in
the diagnosis of mesenteric ischemia
 Sometimes depict the underlying etiology

44.  MDCT is useful in patients with suspected ischemia
because it can :-
 help detect ischemic changes in the affected small
bowel loops and mesentery and
 help determine the cause of the ischemia by allowing
evaluation of the mesenteric vasculature.

45. • MPR
• CT angiograms
• MIP
• VR
• TTP
• Arterial: 35-40 s
• Venous:60 s

46. CT Scan Findings In Mesenteric
Ischemia
Specific CT signs
 Thromboembolism in the mesenteric
vessels
 Lack of bowel enhancement

47.  Circumferential bowel wall thickening:
-Target sign
 Intramural gas
 Portal vein gas
 Focal / diffuse bowel dilatation
 Bowel obstruction
 Increased attenuation of mesenteric fat (edema)
 Vascular engorgement
 Variable enhancement pattern
 Ascites
Nonspecific CT signs

48. Signs of bowel gangrene:
 Large amount of intraperitoneal fluid
 Gas in the mesenteric / portal vessels
 Intramural gas
 Thinned bowel wall with poor or absent
enhancement

49. Paper thin bowel wall

50. White attenuation Grey attenuation

51. Water target sign Pneumatosis intestinalis

65. SMV THROMBOSIS

70. ARTERIAL OCLUSIVE ISCHEMIA VENOUS OCLUSIVE ISCHEMIA
SMA THROMBOSIS SMV THROMBOSIS
NO /SUBTLE BOWEL ENHANCEMENT HYPO/HYPERDENSE BOWEL WALL
THINNED BOWEL WALL (PAPER THIN
BOWEL )
SIGNIFICANT BOWEL WALL
THICKENING
NO MUCOSAL ENHANCEMENT MUCOSAL ENHANCEMENT
BOWEL LOOP DILATATION ONLY AFTER
INFARCTION
DILATED BOWEL LOOPS WITHOUT
INFARCTION
LATE STAGES –MESENTERIC FAT
STRANDING,EDEMA/HEMORRHAGES
MARKED FAT STRANDING AND
HEMORRHAGE

71. Nonocclusive mesenteric ischemia
Systemic low flow state (hypovolemia,
cardiac failure)
Shock bowel
Bowel vasoconstriction
Vasoconstrictor drugs

75. COLONIC ISCHEMIA:
 MOST COMMON FORM OF INTESTINAL
ISCHEMIA
 COMMON IN 7TH DECADE
 MOST COMMON NONOCLUSIVE
CAUSES LIKE HYPOTENSION STATUS
,VASCULITIS AND OTHER
VASCULOPATHIES
CLINICAL FEATURE:
ABDOMINAL PAIN ,BLOODY DIARRHOEA,

79. Chronic M I
Etiology
 Atherosclerosis
 Extrinsic compression
 Vasculitis
 Fibromuscular dysplasia

80. Abdominal Angina
 Intermittent mesenteric ischemia in severe arterial
stenosis with inadequate collateralization
provoked by food ingestion.
 Postprandial abdominal pain (due to "gastric steal"
diverting blood flow away from intestine) .
 Fear of eating large meals .
 Weight loss.
 Malabsorption

81. Diagnosis of intestinal angina is justified
only if …
 At least two of the major mesenteric arteries
are shown to be occluded
and
 Third artery is narrowed by atheroma.
 CMI-Diagnosis by exclusion

83. Computed tomography
 Used to for
-screening the patients with suspected
chronic mesenteric ischemia
-Calcified plaque.
-collateral vessels.

85. CHRONIC MESENTRIC ISCHEMIA
WITH VASCULAR CALCIFICATION
CHRONIC MESENTRIC ISCHEMIA
WITH VASCULAR COLLATERALS

86. Angiography

87. It is the gold standard for
diagnosis of mesenteric vascular
occlusion.

90. 63-year-old woman status post aortic valve replacement who presents with a one
week history of abdominal pain becoming quite severe over the last 24 hours.

92. Role of interventional radiology
 NOMI-
selective catheter-directed administration of
vasodilating agents
 Catheter directed thrombolysis
 Percutaneous transluminal angioplasty
 Fenestration of the aortic dissection.

93. Post OP - Diffuse vasospasm
without occlusions.
Post Papaverine infusion
Arteriogram 24 hr later.
Reversal of vasospasm.

98. ROLE OF MRI

99.  Current role of MRI is yet to be defined.
 True FISP images is used to assess large
mesenteric vessel occlusion
 MRI has significant problem in detecting
small thromboemboli in peripheral vessels
 Routine use of MRI patients with suspected
mesenteric arterial occlusion may not be
justified

100. Sagittal subvolume and coronal subvolume MIP images show severe stenosis of
the celiac, superior mesenteric and inferior mesenteric arteries.

102. REFERENCES :
 GASTROINTESTINAL IMAGING :GORE AND LEVIN
 DIAGNOSTIC IMAGING OF GASTROINTESTINAL
SYSTEM :BERRY

103. Thank you