Imaging Pearls ❯ Small Bowel ❯ CT Angiography
|
-- OR -- |
|
- “Vasculitis represents a range of different diseases that result in inflammation and necrosis of the blood vessels, with different types of vasculitis showing involvement of different types of vasculature. In the past, vasculitis has been divided into 3 categories depending on the caliber of vessels involved: large vessel vasculitis, which involves the aorta and its major branches (eg, Takayasu arteritis, giant cell arteritis); medium vessel arteritis (eg, polyarteritis nodosa [PAN], Kawasaki disease); and small vessel vasculitis (eg, lupus vasculitis, Henoch-Schönlein purpura [HSP], Wegner granulomatosis, Behcet disease).”
Computed Tomography Angiography of the Small Bowel and Mesentery Raman SP, Fishman EK Radiol Clin N Am 54 (2016) 87–100 - “Although most visceral artery dissections merely reflect the extension of an aortic dissection into a branch vessel, isolated visceral artery dissections are still thought to be rare (despite their increasing diagnosis), and almost always reflect an underlying intrinsic weakness of the vessel wall caused by such entities as fibromuscular dysplasia (FMD), cystic medial necrosis, collagen vascular disease, vasculitis, Marfan, or Ehlers-Danlos. The most commonly involved vessel is the SMA, although any visceral artery can theoretically be involved. In most cases, isolated visceral artery dissections occur close to the vessel ostium, possibly as a result of shear stresses to the vessels in this location.”
Computed Tomography Angiography of the Small Bowel and Mesentery Raman SP, Fishman EK Radiol Clin N Am 54 (2016) 87–100 - “Classically diagnosed in elderly patients who have abdominal pain after meals with signs of anorexia and chronic weight loss, chronic mesenteric ischemia is much less common than acute mesenteric ischemia.Most cases are attributable to atherosclerotic narrowing of the origin of the major mesenteric arteries, and symptoms typically result only in patients who have a significant stenosis in at least 2 of the 3 major mesenteric arteries (celiac, SMA, and IMA). However, given that atherosclerotic disease is widespread in the elderly population, the diagnosis of this entity requires not only correlation with appropriate clinical symptoms but also visualization of collateral pathways (eg, celiac-SMA collaterals via the pancreaticoduodenal arcade and SMA-IMA collaterals via the arc of Riolan and marginal artery of Drummond). Although these collateral pathways can compensate for significant stenoses over long periods of time, symptoms usually develop when blood flow via these collaterals is no longer sufficient to supply the bowel.”
Computed Tomography Angiography of the Small Bowel and Mesentery Raman SP, Fishman EK Radiol Clin N Am 54 (2016) 87–100 - “Classically diagnosed in elderly patients who have abdominal pain after meals with signs of anorexia and chronic weight loss, chronic mesenteric ischemia is much less common than acute mesenteric ischemia.Most cases are attributable to atherosclerotic narrowing of the origin of the major mesenteric arteries, and symptoms typically result only in patients who have a significant stenosis in at least 2 of the 3 major mesenteric arteries (celiac, SMA, and IMA).”
Computed Tomography Angiography of the Small Bowel and Mesentery Raman SP, Fishman EK Radiol Clin N Am 54 (2016) 87–100 - “However, given that atherosclerotic disease is widespread in the elderly population, the diagnosis of this entity requires not only correlation with appropriate clinical symptoms but also visualization of collateral pathways (eg, celiac-SMA collaterals via the pancreaticoduodenal arcade and SMA-IMA collaterals via the arc of Riolan and marginal artery of Drummond). Although these collateral pathways can compensate for significant stenoses over long periods of time, symptoms usually develop when blood flow via these collaterals is no longer sufficient to supply the bowel.”
Computed Tomography Angiography of the Small Bowel and Mesentery Raman SP, Fishman EK Radiol Clin N Am 54 (2016) 87–100
- “Intimal flap, thrombosed false lumen and aneurysmal dilatation are the most common CT findings of spontaneous splanchnic artery dissection. In splanchnic artery dissection, conservative management without anticoagulation had good outcome except in patients with bowel ischemia, aneurysmal dilatation three times larger than a normal segment or progression of dissection. ”
Spontaneous Dissection of the Splanchnic Arteries: CT Findings, Treatment and Occlusion
Jung SC et al.
AJR 2013;200:219-225 - “Although surgery should be considered first in the presence of CT findings of bowel infarction, conservative management without anticoagulation therapy has good outcomes in the care of ptients with no bowel ischemia, rupture risk or symptoms.”
Spontaneous Dissection of the Splanchnic Arteries: CT Findings, Treatment and Occlusion
Jung SC et al.
AJR 2013;200:219-225
- Celiac and SMA Dissection: Facts
-Usually isolated finding but both vessels can be involved in up to 10% of cases
-Clinical presentation is persistent abdominal pain but most cases are incidental findings
-Treatment may be conservative (anticoagulation, analgesics and beta blockade)
-Intervention may be necessary with persistent symptoms, expansion of the false lumen or true lumen compromise - Splenic Artery Aneurysms: Etiologies
-Atherosclerosis
-Portal hypertension
-Hepatic transplant
-Pregnancy
-Collagen vascular disease
-Cirrhosis - Mesenteric Artery Aneurysms: Facts
-Most common artery is splenic artery (60%)
-Hepatic artery, SMA, celiac are the other common location in sequential order - SMA Thrombosis: Facts
-SMA occlusion results in acute intestinal ischemia and infarction
-May be a result of thrombus from cardiac thrombus (50%), atrial fibrillation (40%)
-When acute thrombus usually in more distal portion of the SMA than proximal - Celiac and SMA Stenosis: Etiology
-Atherosclerosis (older patients)
-Median arcuate ligament syndrome (younger patients)
-Tumor encasement (pancreatic cancer)
-Pancreatitis - CT Angiography: Mesenteric Artery Evaluation: Protocols
-Phases required depend on the application with two phases usually necessary
-Contrast injection rate is 4-5 cc/sec with contrast volumes in the 80-120 cc volume range
-Contrast used is Omnipaque-350 or Visipaque-320 depending on the patients creatinine or GFR levels
-Arterial phase imaging is usually with a 25-30 second delay and nephrographic phase is at 55-60 seconds - CT Angiography: Mesenteric Artery Evaluation
-Stenosis
-Median arcuate ligament syndrome
-Thrombus
-Aneurysm
-Pseudoaneurysm
-Dissection