- “In conjunction with an appropriate clinical history, several CT findings can suggest the diagnosis of SMA syndrome. These findings include narrowing of the aortomesenteric angle and distance, distension of the stomach and duodenum, and dilatation of the left renal vein with left-sided venous collaterals.”
Superior mesenteric artery syndrome: spectrum of CT findings with multiplanar reconstructions and 3-D imaging
Raman SP, Neyman EG, Horton KM, Eckhauser FE, Fishman EK
Abdom Imaging 2012 Feb 12 (Epub ahead of print)
- Epidemiology of SMA syndrome:
- 0.013–0.78% incidence based on upper gastrointestinal barium studies
- Females are more commonly affected
- Two thirds of patients are between 10 and 39 years old, although it has been reported even
in octogenarians (Figure 12).
- Most commonly associated with severe, debilitating illnesses such as malignancy,
malabsorption syndromes, AIDS, trauma and burns; and with scoliosis surgery - Indirect Radiologic Signs Helpful on Axial Images
- If multiplanar or 3D reconstructions typically performed only after an analysis of the axial
images, these indirect signs are helpful in deciding on further evaluation:
- Dilated left renal vein prior to passing between aorta and SMA
- Dilated venous collaterals, such as lumbar or gonadal vein
- Disease processes in the region - SMA Syndrome Pathophysiology and Direct Radiologic Findings
- Mean angle formed by the superior mesenteric artery and the aorta varies between 38 and
56° with range of 20 to 70° reported
- In SMA syndrome it diminishes to 6-16°
- Mean aortomesenteric distance is 10–28 mm . In SMA syndrome it diminishes to 2-8 mm - Superior Mesenteric Artery (SMA) Syndrome
- SMA syndrome is an uncommon but well recognized clinical entity characterized by
compression of the third, or transverse, portion of the duodenum (D3) between the aorta
and the superior mesenteric artery. - “In each patient, MDCT demonstrated gastric and proximal duodenal dilatation with abrupt narrowing of the third portion of the duodenum between the aorta and SMA. Sagittal maximum intensity projection images reliably demonstrated the decreased aortomesenteric angle (mean in subjects 13.5 degrees, normal range 28 to 65 degrees) and distance (mean in subjects 4.4 mm, normal range 10 to 34 mm) in all 4 patients.”
Multidetector row CT of superior mesenteric artery syndrome
Agrawal GA, Johnson PT, Fishman EK
J Clin Gastroenterol 2007 Jan;41(1):62-65 - “ As opposed to traditional imaging modalities like upper gastrointestinal and mesenteric arteriography, which depict either the bowel or vasculature respectively, CT enables direct visualization of obstructed bowel owing to duodenal compression by the SMA. Multiplanar MDCT with 3-dimensional rendering provides sagittal reconstructions that can be used to confirm the CT criteria of decreased aortomesenteric angle and distance in SMAS.”
Multidetector row CT of superior mesenteric artery syndrome
Agrawal GA, Johnson PT, Fishman EK
J Clin Gastroenterol 2007 Jan;41(1):62-65 - “In each patient, MDCT demonstrated gastric and proximal duodenal dilatation with abrupt narrowing of the third portion of the duodenum between the aorta and SMA. Sagittal maximum intensity projection images reliably demonstrated the decreased aortomesenteric angle (mean in subjects 13.5 degrees, normal range 28 to 65 degrees) and distance (mean in subjects 4.4 mm, normal range 10 to 34 mm) in all 4 patients.”
Multidetector row CT of superior mesenteric artery syndrome
Agrawal GA, Johnson PT, Fishman EK
J Clin Gastroenterol 2007 Jan;41(1):62-65 - “ As opposed to traditional imaging modalities like upper gastrointestinal and mesenteric arteriography, which depict either the bowel or vasculature respectively, CT enables direct visualization of obstructed bowel owing to duodenal compression by the SMA. Multiplanar MDCT with 3-dimensional rendering provides sagittal reconstructions that can be used to confirm the CT criteria of decreased aortomesenteric angle and distance in SMAS.”
Multidetector row CT of superior mesenteric artery syndrome
Agrawal GA, Johnson PT, Fishman EK
J Clin Gastroenterol 2007 Jan;41(1):62-65 - SMA Syndrome:Facts
-SMA angle to aorta normally 45 degrees (range 38-56 degrees) while in SMA syndrome has SMA angle of 6-25 degrees
-SMA to aorta distance normally 10-20 mm while in SMA syndrome is 2-8 mm - SMA Syndrome:Facts
Seen with
-Marked weight loss
-Anorexia nervosa
-Total body casting - SMA Syndrome:aka
-Arteriomesenteric duodenal compression
-Chronic duodenal ileus
-The cast syndrome
-Wilkie’s syndrome - 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 - "Although splanchnic artery aneurysms are relatively rare, they are being diagnosed with increased frequency given the widespread availability of MDCT and 3D imaging capabilities."
MDCT and 3D CT Angiography of Splanchnic Artery Aneurysms
Horton KM, Smith C, Fishman EK
AJR 2007;189:641-647
- "Although splanchnic artery aneurysms are relatively rare, they are being diagnosed with increased frequency given the widespread availability of MDCT and 3D imaging capabilities. It is important that these aneurysms be diagnosed accurately because they can carry a high morbidity and mortality, even in asymptomatic patients."
MDCT and 3D CT Angiography of Splanchnic Artery Aneurysms
Horton KM, Smith C, Fishman EK
AJR 2007;189:641-647
- Splanchnic Artery Aneurysms: Facts
- Incidence of 0.01-0.2% in autopsy series
- Most common is splenic artery aneurysm (60%), with hepatic artery aneurysm being second most popular (20%)
- Aneurysm rupture is associated with high morbidity and mortality
- Splanchnic Artery Aneurysms: Facts
- Splenic artery (60%)
- Hepatic artery (20%)
- SMA (5.5%)
- Celiac artery (4%)
- Pancreatic arteries (2%)
- Gastroduodenal artery (GDA) 1.5%
- Splenic Artery Aneurysms: Facts
- 4x more common in woman than men
- In woman association with pregnancy and multiparity
- Although more common in woman more likely to rupture in men
- Risk of rupture (2-3%) increases with pregnancy, portal hypertension, and after liver tralntation
- Vasculitides that involve the GI Tract
- Takayasu arteritis
- Polyarteritis nodosa
- Wegener granulomatosis
- Churg-Strauss syndrome
- Microscopic polyangitis
- SLE
- Rheumatoid vasculitis
- "Unsuspected mesenteric arterial abnormality may elude diagnosis when axial MDCT sections are interpreted without 3D renderings."
Unsuspected Mesenteric Arterial Abnormality: Comparison of MDCT Axial Sections to Interactive 3D Rendering
Chen JK, Johnson PT, Horton KM, Fishman EK
AJR 2007;189:807-813
- "In the era of isotropic data, perhaps the new standard of care will be to review all MDCT data sets in 3D mode to exclude any unsuspected vascular abnormality."
Unsuspected Mesenteric Arterial Abnormality: Comparison of MDCT Axial Sections to Interactive 3D Rendering
Chen JK, Johnson PT, Horton KM, Fishman EK
AJR 2007;189:807-813
- "This ability to visualize the mesenteric vasculature in real-time using 3D rendering and multiplanar reconstruction is crucial for the comprehensive review of the complex mesenteric vessels."
Mesenteric CT Angiography: A Discussion of Techniques and Selected Applications
Smith Cl, Horton KM, Fishman EK
Tech Vasc Interventional Rad 9:150-155, 2006
- "As CT scanners and 3D imaging software continue to advance, it is very likely that in the near future 3D imaging of the abdomen and abdominal vasculature will become a routine method for review of all CT exams rather than a specialized separate process done in select cases."
Mesenteric CT Angiography: A Discussion of Techniques and Selected Applications
Smith Cl, Horton KM, Fishman EK
Tech Vasc Interventional Rad 9:150-155, 2006
- Superior Mesenteric Artery Aneurysms: Facts
- 3rd most common visceral artery aneurysm
- 5.5% of visceral artery aneurysms
- Usually located in the first 5 cm of the SMA
- Etiology ranges from pancreatitis and mass effect of pseudocyst to autodigestion of vessel wall by pancreatic enzymes to trauma
- Superior Mesenteric Artery Aneurysms: Etiology
- Pancreatitis
- Nonsurgical trauma
- Surgical trauma
- Arteriosclerosis
- Infection
- Collagen vascular disease
- Arteritis
- Dissection
- Superior Mesenteric Artery Aneurysms: Presentation
- Abdominal pain
- Back pain
- Bleeding
- Rupture
- Current therapy: resect all aneurysms or pseudoaneurysms greater than 2 cm
- "Multidetector CT may offer a distinct advantage over traditional single-detector CT in the evaluation of mesenteric vasculature.Narrower collimation coupled with shorter scanning times reduces motion artifact and permits scanning during peak IV Contrast enhancement, which improves both axial and reformatted images."
Bowel Obstruction Revealed by Multidetector CT
Khurana B et al.
AJR 2002;178:1139-1144
- Polyarteritis Nodosa: Facts
- Systemic necrotizing vasculitis that affects small and medium size arteries
- GI tract involvement is seen in up to 50% of patients
- Common sites of involvement; kidneys, heart, liver, CNS and skin
- Polyarteritis Nodosa: Angiographic Findings
- Aneurysms in the 1-5 mm range
- Vascular ectasia
- Stenosis or occlusion of vessels
- Intraparenchymal infarction
- Aneurysm rupture
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