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Vascular: Sma Imaging Pearls - Learning Modules | CT Scanning | CT Imaging | CT Scan Protocols - CTisus
Imaging Pearls ❯ Vascular ❯ SMA
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  • Mesenteric Artery Dissection
    • Isolated celiac or SMA dissection
    • Exclusive of aortic dissection
    • 10% of patients celiac and SMA involved
    • May present acutely w/ abdominal pain
    • Often incidentally identified on CT
       - typically stable without complication
  • Mesenteric Artery Dissection
    • atherosclerosis
    • vasculitis
    • connective tissue disorder
    • Type IV Ehlers-Danlos
    • Trauma
    • fibromuscular dysplasia
    • cystic medial necrosis
    • Hypertension
    • Systemic arterial mediolysis
  • Segmental Arterial Mediolysis
    • Rare noninflammatory vasculopathy
    • Medial layer disrupted
    • Dissection, hemorrhage, ischemia
    • Visceral and mesenteric arteries most common
    • Abdominal pain, GI bleeding
  • Segmental Arterial Mediolysis: CT
    • String of beads
    • Stenoses
    • Aneurysms
    • Dissection
    • Thrombosis
  • SAM: Differential Dx
    • FMD
    • PAN
    • ANCA assoc vaculitis
    • Giant cell arteritis
    • Takayasus
    • Bechets
    • Type IV EDS
  • Superior Mesenteric Artery Syndrome
    • Obstruction of the third portion of the duodenum between the SMA and aorta
    • Cast syndrome, Wilke syndrome
    • Arteriomesenteric duodenal compression syndrome
  • SMAS: CT Criteria
    • Aortomesenteric angle
       - Normally 28 to 65 degrees
       - Reduced to < 22 degrees in SMAS
    • Aortomesenteric distance
       - Normally 10-34 mm
       - Less than 8 mm in SMAS
    • Dilated duodenum and stomach proximal
    • Obstructed left renal vein (“nutcracker”)
  • SMA Thrombosis: Causes
    • Embolic
    • Progression of atherosclerosis
    • Trauma
    • Infection
    • Spontaneous
  • SMA Occlusion
    Embolism (57%) > thrombosis
    • half of patients with SMA embolus have cardiac thrombus
    • 40% have atrial fibrillation
    • occlusion more likely to be distally located in the SMA
    • synchronous emboli in other locations in 68%
    Thrombotic occlusion
    • more extensive intestinal infarction
  • Mesenteric Artery Stenosis
    • Atherosclerosis in older patients
    • Median arcuate ligament syndrome
       - younger patients
    • Other causes
       - tumor encasement (pancreatic cancer)
       - pancreatitis
       - vasculitis
  • Mesenteric Ischemia
    • Chronic mesenteric ischemia is caused by occlusive disease of mesenteric vessels
    • Most often due to atheroma
    • Women > men
    • Patients >60 years
    • Severe stenosis (often multivessel) manifests with abdominal pain or other nonspecific symptoms
  • Chronic Mesenteric Ischemia
    • Takayasu disease
    • fibromuscular dysplasia
    • thromboangiitis obliterans
    • periarteritis nodosum
    • radiation therapy
    • median arcuate ligament syndrome
  • “Originally described by Rokitansky in 1861, superior mesenteric artery syndrome (SMAS) is a relatively rare condition caused by obstruction of the third portion of the duodenum between the SMA and aorta. The condition has also been called cast syndrome, Wilke syndrome, or arteriomesenteric duodenal compression syndrome. Because of its relative infrequency, the incidence of the disorder is not well known. However, estimated incidence rates based on gastrointestinal barium series are from 0.01% to 0.33%.”


    Multidetector Row CT of Superior Mesenteric Artery Syndrome 
Gautam A. Agrawal, Pamela T. Johnson, Elliot K. Fishman 
J Clin Gastroenterol 2007;41:62–65

  • “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-dimen- sional 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 
Gautam A. Agrawal, Pamela T. Johnson, Elliot K. Fishman 
J Clin Gastroenterol 2007;41:62–65

  • “When conservative management fails, surgical treatment is employed. Surgical management includes duodenojejunostomy, gastrojejunostomy, or lysis of the ligament of Treitz with derotation of the bowel (Strong’s operation). After unsuccessful conservative management, surgical correction was required in 2/3 of patients in 1 small series.”


    Multidetector Row CT of Superior Mesenteric Artery Syndrome 
Gautam A. Agrawal, Pamela T. Johnson, Elliot K. Fishman 
J Clin Gastroenterol 2007;41:62–65

  • An entity first described almost 150 years ago, ‘‘superior mesenteric artery (SMA) syndrome’’ represents a unique set of clinical symptoms caused by compression of the duodenum between the aorta and SMA. Classically described in young women, patients experience early post-prandial satiety, abdominal pain, nausea, and vomiting, often resulting in chronic anorexia and weight loss.

    
Superior mesenteric artery syndrome: spectrum of CT findings with multiplanar reconstructions and 3-D imaging 
Siva P. Raman, Edward G. Neyman, Karen M. Horton, Frederic E. Eckhauser, Elliot K. Fishman 
 Abdom Imaging (2012) 37:1079–1088 

  • “SMA syndrome is thought to result from an abnormally short distance between the aorta and SMA, which results in compression of the duodenum. Patients with SMA syndrome usually present with nonspecific symptoms, making diagnosis extremely difficult. Typically seen in young women, their chronic anorexia, nausea, vomiting, and post- prandial abdominal pain are often blamed on non-anatomic, psychosocial causes, resulting in a delayed diagnosis. Nevertheless, when carefully questioned, these patients often have a characteristic history, with their symptoms relieved by changes in posture, such as turning to their left side, bringing their knees up to their chest, or the prone position.”


    Superior mesenteric artery syndrome: spectrum of CT findings with multiplanar reconstructions and 3-D imaging 
Siva P. Raman, Edward G. Neyman, Karen M. Horton, Frederic E. Eckhauser, Elliot K. Fishman 
 Abdom Imaging (2012) 37:1079–1088 

  • “In a normal patient, the distance between the aorta and SMA (‘‘aortomesenteric distance’’) should range from 10 to 34 mm, and the normal angle between the aorta and SMA (‘‘aortomesenteric angle’’) should be between 28° to 65°. Angiographic studies have shown that patients with SMA syndrome clearly have an abnormal aortomesenteric angle (6°–22°), and a shortened aorto-mesenteric distance (2–8 mm) compared to normal patients.”


    Superior mesenteric artery syndrome: spectrum of CT findings with multiplanar reconstructions and 3-D imaging 
Siva P. Raman, Edward G. Neyman, Karen M. Horton, Frederic E. Eckhauser, Elliot K. Fishman 
 Abdom Imaging (2012) 37:1079–1088
  • “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
  • “The classic phenotypic appearance of the aorta in patients with Marfan syndrome is annuloaortic ectasia, with dilatation of the aortic annulus and sinuses of Valsalva, and effacement of the sinotubular junction, resulting in a tulip-shaped configuration of the aortic root.” 


    Pre- and Postoperative Imaging of the Aortic Root 
Hanneman K et al. 
RadioGraphics 2016; 36:19-37
  • “Fast scanning along with high resolution of multidetector computed tomography (MDCT) have expanded the role of non-invasive imaging of splanchnic arteries. Advancements in both MDCT scanner technology and three-dimensional (3D) imaging software provide a unique opportunity for non-invasive investigation of splanchnic arteries. Although standard axial computed tomography (CT) images allow identification of splanchnic arteries, visualization of small or distal branches is often limited. Similarly, a comprehensive assessment of the complex anatomy of splanchnic arteries is often beyond the reach of axial images.”
    Three-dimensional MDCT angiography of splanchnic arteries: Pearls and pitfalls.
    Dohan A et al.
    Diagn Interv Imaging. 2014 Jun 30. pii: S2211-5684(14)00202-2. doi: 10.1016/j.diii.2014.06.011. [Epub ahead of print
  •  “However, the submillimeter collimation that can be achieved with MDCT scanners now allows the acquisition of true isotropic data so that a high spatial resolution is now maintained in any imaging plane and in 3D mode. This ability to visualize the complex network of splanchnic arteries using 3D rendering and multiplanar reconstruction is of major importance for an optimal analysis in many situations.”
    Three-dimensional MDCT angiography of splanchnic arteries: Pearls and pitfalls.
    Dohan A et al.
    Diagn Interv Imaging. 2014 Jun 30. pii: S2211-5684(14)00202-2. doi: 10.1016/j.diii.2014.06.011. [Epub ahead of print
  • “ Twenty-four celiac and 18 SMA dissections were detected in 38 patients. One third of the dissections diagnosed with interactive multiplanar reconstruction/maximum intensity projection (MIP)/3-dimensional (3D) rendering were missed on standard imaging planes. No patients had bowel ischemia or died. Eighty-four percent of the patients were observed, 2 patients received anticoagulation, 2 patients received surgical repair, and 3 patients received stenting. Twenty-three of 25 cases treated with observation exhibited no change or improvement/resolution (2/25) with 20.9-month mean follow-up.”
    Isolated celiac and superior mesenteric artery dissection identified with MDCT: imaging findings and clinical course.
    Verde F, Bleich KB, Oshmyansky A, Black JH, Fishman EK, Johnson PT.
    J Comput Assist Tomogr. 2012 Sep-Oct;36(5):539-45.
  • “ Twenty-four celiac and 18 SMA dissections were detected in 38 patients. One third of the dissections diagnosed with interactive multiplanar reconstruction/maximum intensity projection (MIP)/3-dimensional (3D) rendering were missed on standard imaging planes.”
    Isolated celiac and superior mesenteric artery dissection identified with MDCT: imaging findings and clinical course.
    Verde F, Bleich KB, Oshmyansky A, Black JH, Fishman EK, Johnson PT.
    J Comput Assist Tomogr. 2012 Sep-Oct;36(5):539-45.
  • “Most isolated celiac and SMA dissections were asymptomatic/incidental, supporting observation and surveillance with intervention reserved for vascular compromise. Interactive multiplanar reconstruction/maximum intensity projection/3D rendering can increase diagnostic sensitivity.”
    Isolated celiac and superior mesenteric artery dissection identified with MDCT: imaging findings and clinical course.
    Verde F, Bleich KB, Oshmyansky A, Black JH, Fishman EK, Johnson PT.
    J Comput Assist Tomogr. 2012 Sep-Oct;36(5):539-45.
  • “ Acute thromboembolic occlusion in the superior mesenteric artery (SMA) is a condition with high mortality and morbidity. Multi-detector computerised tomography with intravenous contrast enhancement (MDCTiv) may improve diagnostic accuracy and survival.”
    Impact of MDCT with intravenous contrast on the survival in patients with acute superior mesenteric artery occlusion
    Wadman M et al.
    Emerg Radiol. 2010 May;17(3):171-8
  • “Examination with MDCTiv in patients with acute SMA occlusion was associated with survival benefit. Hence, MDCTiv seems to be the method of choice in the workup phase. Radiologists should routinely describe the mesenteric vessels in patients with acute abdomen even when the diagnosis is not asked for. Patients with high creatinine levels are at risk to be examined without intravenous contrast, and survival in these patients is poor.”
    Impact of MDCT with intravenous contrast on the survival in patients with acute superior mesenteric artery occlusion
    Wadman M et al.
    Emerg Radiol. 2010 May;17(3):171-8
  • “ Radiologists should routinely describe the mesenteric vessels in patients with acute abdomen even when the diagnosis is not asked for. Patients with high creatinine levels are at risk to be examined without intravenous contrast, and survival in these patients is poor.”
    Impact of MDCT with intravenous contrast on the survival in patients with acute superior mesenteric artery occlusion
    Wadman M et al.
    Emerg Radiol. 2010 May;17(3):171-8
  • SMA Occlusion: Causes
    - Superior Mesenteric Artery Embolism (50%)
    - Cardiac thrombus source is most common
    - Asoociated with other emboli (20%)
    - Malignancy
    - Coagulation disorder
    - Associated with underlying cardiovascular disease
    - Cardiac Arrhythmia
    - Myocardial Infarction
    - Valvular Disease
    - Superior Mesenteric Artery Thrombosis (15-25%)
    - Underlying Chronic Mesenteric Ischemia
    - Associated conditions
    - Abdominal Trauma
    - Acute infection
  •  “Acute intestinal ischemia is an abdominal emergency occurring in nearly 1% of patients presenting with acute abdomen. The causes can be occlusive or non occlusive. Early diagnosis is important to improve survival rates. In most cases of late or missed diagnosis, the mortality rate from intestinal infarction is very high, with a reported value ranging from 60% to 90%. Multi-detector computed tomography (MDCT) is a fundamental imaging technique that must be promptly performed in all patients with suspected bowel ischemia.”
    Multi-detector CT features of acute intestinal ischemia and their prognostic correlations.
    Moschetta M et al.
    World J Radiol. 2014 May 28;6(5):130-8.
  •  “Acute intestinal ischemia is an abdominal emergency occurring in nearly 1% of patients presenting with acute abdomen. The causes can be occlusive or non occlusive. Early diagnosis is important to improve survival rates. In most cases of late or missed diagnosis, the mortality rate from intestinal infarction is very high, with a reported value ranging from 60% to 90%.”
    Multi-detector CT features of acute intestinal ischemia and their prognostic correlations.
    Moschetta M et al.
    World J Radiol. 2014 May 28;6(5):130-8.
  • “The increased spatial and temporal resolution, high-quality multi-planar reconstructions, maximum intensity projections, vessel probe, surface-shaded volume rending and tissue transition projections make MDCT the gold standard for the diagnosis of intestinal ischemia, with reported sensitivity, specificity, positive and negative predictive values of 64%-93%, 92%-100%, 90%-100% and 94%-98%, respectively. MDCT contributes to appropriate treatment planning and provides important prognostic information thanks to its ability to define the nature and extent of the disease.”
    Multi-detector CT features of acute intestinal ischemia and their prognostic correlations.
    Moschetta M et al.
    World J Radiol. 2014 May 28;6(5):130-8.
  •  “MDCT contributes to appropriate treatment planning and provides important prognostic information thanks to its ability to define the nature and extent of the disease.”
    Multi-detector CT features of acute intestinal ischemia and their prognostic correlations.
    Moschetta M et al.
    World J Radiol. 2014 May 28;6(5):130-8.
  •  “Bowel wall hyperdensity reflects vasodilation, which is the first consequence of hypoxic damage. The absence of wall enhancement corresponds to the ensuing vasoconstriction; bowel-loop thickening and dilatation are related to the increased capillary permeability, pneumatosis and the presence of air within the mesenteric-portal system reflect the necrosis of the intestinal mucosa, whereas pneumoperitoneum/pneumoretroperitoneum corresponds to a transmural extension of the necrosis. Therefore, wall hyperdensity, the absence of enhancement and wall thickening are an early stage of the disease, in contrast to loop dilation, parietal and portomesenteric pneumatosis and pneumoperitoneum/pneumoretroperitoneum which reflect an advanced stage of disease and are characterized by high mortality rates.”
    Multi-detector CT features of acute intestinal ischemia and their prognostic correlations.
    Moschetta M et al.
    World J Radiol. 2014 May 28;6(5):130-8.
  •  “Bowel wall hyperdensity reflects vasodilation, which is the first consequence of hypoxic damage. The absence of wall enhancement corresponds to the ensuing vasoconstriction; bowel-loop thickening and dilatation are related to the increased capillary permeability, pneumatosis and the presence of air within the mesenteric-portal system reflect the necrosis of the intestinal mucosa, whereas pneumoperitoneum/pneumoretroperitoneum corresponds to a transmural extension of the necrosis.”
    Multi-detector CT features of acute intestinal ischemia and their prognostic correlations.
    Moschetta M et al.
    World J Radiol. 2014 May 28;6(5):130-8.
  •  “Bowel infarction is an uncommon but often underestimated cause of non traumatic acute abdomen and early diagnosis is crucial in order to avoid irreversible damage to the bowel wall. MDCT is a fundamental imaging technique that must be promptly performed in all patients with acute abdomen and suspected bowel ischemia. Thanks to the dedicated reconstruction program, its diagnostic potential is much improved compared to the past and currently is superior to that of any other noninvasive technique.”
    Multi-detector CT features of acute intestinal ischemia and their prognostic correlations.
    Moschetta M et al.
    World J Radiol. 2014 May 28;6(5):130-8.
  •  “MDCT contributes to appropriate treatment planning and provides important prognostic information thanks to its ability to define the nature and extent of the disease.”
    Multi-detector CT features of acute intestinal ischemia and their prognostic correlations.
    Moschetta M et al.
    World J Radiol. 2014 May 28;6(5):130-8.
  •  “Bowel wall hyperdensity reflects vasodilation, which is the first consequence of hypoxic damage. The absence of wall enhancement corresponds to the ensuing vasoconstriction; bowel-loop thickening and dilatation are related to the increased capillary permeability, pneumatosis and the presence of air within the mesenteric-portal system reflect the necrosis of the intestinal mucosa, whereas pneumoperitoneum/pneumoretroperitoneum corresponds to a transmural extension of the necrosis. Therefore, wall hyperdensity, the absence of enhancement and wall thickening are an early stage of the disease, in contrast to loop dilation, parietal and portomesenteric pneumatosis and pneumoperitoneum/pneumoretroperitoneum which reflect an advanced stage of disease and are characterized by high mortality rates.”
    Multi-detector CT features of acute intestinal ischemia and their prognostic correlations.
    Moschetta M et al.
    World J Radiol. 2014 May 28;6(5):130-8.
  •  “Bowel wall hyperdensity reflects vasodilation, which is the first consequence of hypoxic damage. The absence of wall enhancement corresponds to the ensuing vasoconstriction; bowel-loop thickening and dilatation are related to the increased capillary permeability, pneumatosis and the presence of air within the mesenteric-portal system reflect the necrosis of the intestinal mucosa, whereas pneumoperitoneum/pneumoretroperitoneum corresponds to a transmural extension of the necrosis.”
    Multi-detector CT features of acute intestinal ischemia and their prognostic correlations.
    Moschetta M et al.
    World J Radiol. 2014 May 28;6(5):130-8.
  •  “Bowel infarction is an uncommon but often underestimated cause of non traumatic acute abdomen and early diagnosis is crucial in order to avoid irreversible damage to the bowel wall. MDCT is a fundamental imaging technique that must be promptly performed in all patients with acute abdomen and suspected bowel ischemia. Thanks to the dedicated reconstruction program, its diagnostic potential is much improved compared to the past and currently is superior to that of any other noninvasive technique.”
    Multi-detector CT features of acute intestinal ischemia and their prognostic correlations.
    Moschetta M et al.
    World J Radiol. 2014 May 28;6(5):130-8.
  • “Intravascular thrombosis and thromboembolism are critical diagnoses which are frequently made on contrast-enhanced computed tomography (CECT) or Doppler ultrasound. For a variety of reasons, some patients with acute intravascular pathology are imaged using CT without intravenous contrast. In the acute setting, the increased Hounsfield unit (HU) density of the thrombus compared to the blood pool allows the diagnosis to be made, or at least suggested, on non-enhanced computed tomography (NECT). The increased density of the clot is commonly referred to as the "hyperdense vessel sign." This is a well-known finding in the setting of stroke, but hyperdense vessels can also signal arterial or venous thrombosis in the chest, abdomen, pelvis, and extremities. Once a hyperdense vessel sign is noted on NECT, further exploration with CECT, angiography, or ultrasound may then be performed. Here, we present a pictorial review of the appearance of acute intravascular thrombosis as seen on non-enhanced computed tomography.”
    Imaging findings of acute intravascular thrombus on non-enhanced computed tomography.
    Whitesell RT, Steenburg SD.
    Emerg Radiol. 2014 Jun;21(3):271-7
  • “Intravascular thrombosis and thromboembolism are critical diagnoses which are frequently made on contrast-enhanced computed tomography (CECT) or Doppler ultrasound. For a variety of reasons, some patients with acute intravascular pathology are imaged using CT without intravenous contrast. In the acute setting, the increased Hounsfield unit (HU) density of the thrombus compared to the blood pool allows the diagnosis to be made, or at least suggested, on non-enhanced computed tomography (NECT). The increased density of the clot is commonly referred to as the "hyperdense vessel sign." This is a well-known finding in the setting of stroke, but hyperdense vessels can also signal arterial or venous thrombosis in the chest, abdomen, pelvis, and extremities. Once a hyperdense vessel sign is noted on NECT, further exploration with CECT, angiography, or ultrasound may then be performed.”
    Imaging findings of acute intravascular thrombus on non-enhanced computed tomography.
    Whitesell RT, Steenburg SD.
    Emerg Radiol. 2014 Jun;21(3):271-7
  • “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 outcome
    Jung SC et al.
    AJR Am J Roentgenol. 2013 Jan;200(1):219-25
  • “Some investigators have suggested several risk factors, including cystic medial necrosis, fibromuscular dysplasia, segmental mediolytic arteriopathy, atherosclerosis, hypertension, pregnancy, and connective tissue disorders. In most reports and in our study, significant cor- relations with risk factors have been unclear.”
    Spontaneous dissection of the splanchnic arteries: CT findings, treatment, and outcome
    Jung SC et al.
    AJR Am J Roentgenol. 2013 Jan;200(1):219-25
  • “Intimal flap, thrombosed false lumen, and aneurysmal dilatation are the most common
    CT findings of spontaneous dissection of the splanchnic arteries. Bowel ischemia, aneurysmal dilatation three times the normal arterial diameter, and progression of dissection
    were the most important CT findings to indicate the need for endovascular stent insertion or surgery.”
    Spontaneous dissection of the splanchnic arteries: CT findings, treatment, and outcome
    Jung SC et al.
    AJR Am J Roentgenol. 2013 Jan;200(1):219-25
  • “ Percutaneous endovascular treatment using a covered stent may be a safe and feasible tool for SMA pseudoaneurysm.”
    Endovascular Treatment of Superior Mesenteric Artery Pseudoaneurysm Using Covered Stents in Six Patients
    Kim SW et al.
    AJR 2014; 203:432-438
  • “ Superior mesenteric artery (SMA) pseudoaneurysms are potentially life-threatening because of the risk of massive fatal hemorrhage and acute mesenteric ischemia. SMA pseudoaneurysms are rare with an incidence of only 0.01-2.6%, limiting our understanding of their pathophysiology and natural history.”
    Endovascular Treatment of Superior Mesenteric Artery Pseudoaneurysm Using Covered Stents in Six Patients
    Kim SW et al.
    AJR 2014; 203:432-438
  • “ In conclusion, our study shows that placement of covered stents for the treatment of SMA pseudoaneurysms can lead to technical success and clinical success with midterm stent patency. Therefore, percutaneous endovscular treatment using a covered stent may be a safe and feasible tool for the treatment of SMA pseudoaneurysms.”
    Endovascular Treatment of Superior Mesenteric Artery Pseudoaneurysm Using Covered Stents in Six Patients
    Kim SW et al.
    AJR 2014; 203:432-438
  • “Segmental arterial mediolysis (SAM) is a rare vasculopathy of unknown etiology characterized by disruption of the arterial medial layer, with resultant susceptibility to vessel dissection, hemorrhage, and ischemia.”
    Clinical diagnosis of segmental arterial mediolysis: Differentiation from vasculitis and other mimics
    Baker-LePain JC et al
    Arthritis Care Res 2010, 62: 1655–1660.
  • “ Although the abdominal visceral arteries are most frequently affected in SAM , any vessel may be involved, including the retroperitoneal , intracranial , and coronary arteries. The histopathologic changes begin with vacuolar degeneration of smooth muscle cells in the arterial media, followed by fibrin deposition at the medial–adventitial junction . This in turn predisposes to dissecting aneurysms.”
    Clinical diagnosis of segmental arterial mediolysis: Differentiation from vasculitis and other mimics
    Baker-LePain JC et al
    Arthritis Care Res 2010, 62: 1655–1660.
  • “ The angiographic appearance of SAM is variable, ranging from arterial dilation to aneurysm formation (single or multiple) to stenoses or occlusion, frequently with dissection . Correspondingly, symptoms arise both from stenoses and occlusions (e.g., postprandial pain from intestinal ischemia) and from dissections and aneurysms (e.g., sudden and catastrophic intraperitoneal bleeding).”
    Clinical diagnosis of segmental arterial mediolysis: Differentiation from vasculitis and other mimics
    Baker-LePain JC et al
    Arthritis Care Res 2010, 62: 1655–1660.
  • “The differential diagnosis of SAM includes atherosclerosis, fibromuscular dysplasia (FMD), infection (e.g., mycotic aneurysm and endocarditis), connective tissue diseases (e.g., Behçet's disease and polyarteritis nodosa [PAN]), neurofibromatosis, and inherited defects in vessel wall structural proteins (e.g., type IV Ehlers-Danlos syndrome and Marfan's syndrome). ”
    Clinical diagnosis of segmental arterial mediolysis: Differentiation from vasculitis and other mimics
    Baker-LePain JC et al
    Arthritis Care Res 2010, 62: 1655–1660.
  • “In summary, SAM is a rare but important cause of unexplained vascular lesions in patients in whom other inflammatory, infectious, or heritable diseases have been ruled out. The diagnosis should be considered when a patient presents with unexplained acute-onset abdominal pain with or without intraabdominal bleeding. SAM should also be kept in mind when aneurysms, stenoses, and occlusions are identified in medium-sized and large vessels, especially when these lesions are limited to a single anatomic location.”
    Clinical diagnosis of segmental arterial mediolysis: Differentiation from vasculitis and other mimics
    Baker-LePain JC et al
    Arthritis Care Res 2010, 62: 1655–1660.
  • “ The discrimination of SAM from systemic inflammatory vasculitides is particularly important, since corticosteroids and immunosuppressive agents, which are crucial in the treatment of the inflammatory vasculitides, have no proven benefit in SAM. Without any evidence of an inflammatory etiology, the use of immunosuppressive regimens in SAM exposes the patient to undue risks, including infection and poor wound healing, and could possibly worsen the prognosis. Treatment of SAM involves embolization, surgical bypass, or resection of the injured arteries.”
    Clinical diagnosis of segmental arterial mediolysis: Differentiation from vasculitis and other mimics
    Baker-LePain JC et al
    Arthritis Care Res 2010, 62: 1655–1660.
  • “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
© 1999-2017 Elliot K. Fishman, MD, FACR. All rights reserved.