Everything you need to know about Computed Tomography (CT) & CT Scanning

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Vascular: Celiac Imaging Pearls - Learning Modules | CT Scanning | CT Imaging | CT Scan Protocols - CTisus
Imaging Pearls ❯ Vascular ❯ Celiac
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  • Median Arcuate Ligament Syndrome
    • Median arcuate ligament runs obliquely between the diaphragmatic crura
    • Low lying ligament can compress celiac artery
    • Various degrees of narrowing and obstruction
    • Median Arcuate Ligament “Syndrome” if patient symptomatic
  • Visceral Arterial Aneurysms
    • splenic artery in 60%–80% of cases
    • hepatic artery in 20%
    • SMA in 5.5%
    • celiac artery in 4%
    • gastric and gastroepiploic artery in 4%,
    • GDA, pancreatic branches in 6%
    • jejunal and ileocolic arteries in 3%
    • IMA in less than 1%
  • Splenic Artery Aneurysms
    • Small and asymptomatic- serial imaging
    • Surgical intervention at 2 cm
    • More aggressive management may be warranted in high risk clinical settings
       - women of childbearing age
       - cirrhotics
  • Celiac Artery Aneurysms
    • Post-stenotic dilatation w/proximal stenosis
    • Atherosclerosis
    • Focal dissection
    • Medial degeneration
    • Genetic syndrome: Ehlers Danlos
  • Celiac Artery Aneurysms
    • Rupture or impending rupture are made apparent by signs and symptoms
       - pain
       - gastrointestinal bleeding
    • Size threshold for surgical repair of celiac artery aneurysms 2 cm in surgical candidates
  • Visceral Arterial Aneurysms
    • Treatment options include surgical vs endovascular approaches based on location
    • For many cases, ligation or coil embolization is the treatment of choice
    • Stents are used primarily in cases of aneurysms of major branches, where preservation of arterial flow is required
  • Pseudoaneurysms
    • Nearly always present with symptoms
    • Only 2.5% of cases presented incidentally
    • Untreated mortality rate approaches 90%
    • Small and large aneurysms can rupture
    • Emergent coil embolization
  • “The celiac artery is the first major anterior infra- diaphragmatic branch of the abdominal aorta, fol- lowed by the superior mesenteric artery (SMA) and inferior mesenteric artery. With the most common branching pattern of the celiac axis, the left gastric artery branches first and the celiac trunk then divides into the common hepatic and splenic arteries. This pattern is seen in approximately 70% of individuals. Several other variants have been described, such as a true trifurcation of all 3 ves- sels from the terminal portion of the celiac axis, and combined trunks when one vessel is replaced from a different arterial bed.”


    Computed Tomography Angiography of the Hepatic, Pancreatic, and Splenic Circulation 
Price M, Patino M, Sahani D
Radiol Clin N Am 54 (2016) 55–70
  • “Classic branching of the hepatic artery is observed in The common hepatic artery (CHA) originates from the celiac trunk, giving off the gastroduodenal artery as the first branch, and continues to the porta hepatis as the proper hepatic artery. The right gastric artery originates from the proper hepatic artery at the portal hilum. The proper hepatic artery then finally divides into its 3 terminal branches: the right, middle, and left hepatic arteries.”


    Computed Tomography Angiography of the Hepatic, Pancreatic, and Splenic Circulation 
Price M, Patino M, Sahani D
Radiol Clin N Am 54 (2016) 55–70
  • “Classic branching of the hepatic artery is observed in approximately 60% of people. Variant origins of the CHA are rare and seen in only approximately 4% of individuals. In people with a replaced CHA, 50% have an origin from the SMA and the remainder are usually replaced to the abdominal aorta. In patients who have a CHA that arises from the SMA, the artery typically maintains a suprapancreatic position but courses posterior to the main portal vein and superior mesenteric vein (SMV), unlike in the normal CHA anatomy. The CHA maintains a suprapancreatic, preportal pathway when it arises from the abdominal aorta.”


    Computed Tomography Angiography of the Hepatic, Pancreatic, and Splenic Circulation 
Price M, Patino M, Sahani D
Radiol Clin N Am 54 (2016) 55–70
  • “Metastatic lesions to the pancreas are uncommon and account for fewer than 5% of all pancreatic malignancies.Primary tumors of the kidney, thyroid, lung, and breast, as well as melanoma have been reported to metastasize to the pancreatic parenchyma. It is important to note that because these metastatic lesions can invade the ductal epithelium, they may produce ductal dilatation and mimic pancreatic adenocarcinoma. Metastases from renal cell carcinoma (RCC) may be found at the time of primary tumor diagnosis or, more frequently, during follow-up after surgery, and though these lesions can be solitary, they have been reported to be multiple in 20% to 45 % of patients. RCC is the most common primary tumor leading to solitary pancreatic metastases.These lesions are usually round or ovoid masses, well-delineated, and show brisk enhancement in the pancreatic late arterial phase and washout on delayed phase images. Based on enhancement alone, it can be difficult to differentiate these metastatic lesions from hypervascular neuroendocrine tumors of the pancreas.”


    Computed Tomography Angiography of the Hepatic, Pancreatic, and Splenic Circulation 
Price M, Patino M, Sahani D
Radiol Clin N Am 54 (2016) 55–70
  • “Abdominal aneurysms and pseudoaneurysms represent an important finding every emergency radiologist must detect. True aneurysms are usually incidental to the presenting complaint, whereas pseudoaneurysms are nearly always symptomatic.”

    Review of visceral aneurysms and pseudoaneurysms.
Lu M et al.
J Comput Assist Tomogr. 2015 Jan-Feb;39(1):1-6.
  • Gastroduodenal (GDA) Artery Pseudoaneurysms: Etiology
    - Iatrogenic injury (bx)
    - Whipple procedure
    - Pancreatitis
    - Vasculitis
  • “The median arcuate ligament syndrome (or celiac artery compression syndrome) was first described in 1963 by Harjola (3). The definition of the syndrome relies on a combination of both clinical and radiographic features. It typically occurs in young patients (20–40 years of age) and is more common in thin women, who may present with epigastric pain and weight loss (4). The abdominal pain may be associated with eating, but not always (5). At physical examination, an abdominal bruit that varies with respiration may be audible in the midepigastric region. Symptoms are thought to arise from the compression of the celiac axis, resulting in a compromise in blood flow.”
    A postoperative aneurysm may be either a “true” aneurysm that includes all layers of the vascular wall or a pseudoaneurysm, such as occurred in our patient. A true aneurysm can occur if the native aorta is not excised to the level of the renal arteries at the original surgery, which leaves a segment of aorta that is susceptible to aneurysm formation. Potential causes of pseudoaneurysm formation include technical error and infection. Graft infections are a potentially important causal factor in pseudoaneurysm formation. Some studies have found that more than 50% of pseudoaneurysms without clinical evidence of infection are in fact culture positive. The most frequently isolated organisms have been Staphylococcus epidermidis and other staphylococcal species. It is theorized that these bacteria release cytolysins, which can result in graft disruption.
    “ A postoperative aneurysm may be either a “true” aneurysm that includes all layers of the vascular wall or a pseudoaneurysm, such as occurred in our patient. A true aneurysm can occur if the native aorta is not excised to the level of the renal arteries at the original surgery, which leaves a segment of aorta that is susceptible to aneurysm formation. Potential causes of pseudoaneurysm formation include technical error and infection. Graft infections are a potentially important causal factor in pseudoaneurysm formation.”
    Aortic Pseudoaneurysm
    Takach TJ, Cervera RD, Gregoric ID
    Tex Heart Inst J 2005; 32(2): 235-237
  • “ Once the disorder has been diagnosed, surgery can be performed to relieve the compression. In some patients, the ligamentous constriction of the celiac axis causes vascular damage, which may require vascular reconstruction. CT angiography can play a role in the diagnosis of median arcuate ligament syndrome by demonstrating the characteristic focal narrowing of the celiac artery in patients presenting with the appropriate clinical symptoms.”
    Median Arcuate Ligament Syndrome: Evaluation with CT Angiography
    Horton KM, Talamini MA, Fishman EK
    RadioGrapgics 25.1177-1182
  • “ The median arcuate ligament is a fibrous arch that unites the diaphragmatic crura on either side of the aortic hiatus. The ligament usually passes superior to the origin of the celiac axis. However, in some people, the ligament inserts low and thus crosses the proximal portion of the celiac axis, causing compression and sometimes resulting in abdominal pain. The diagnosis of clinically significant celiac axis compression, referred to as median arcuate ligament syndrome, is traditionally made with conventional angiography; however, the condition can now be diagnosed with three-dimensional computed tomographic (CT) angiography. In patients with median arcuate ligament syndrome, CT angiograms demonstrate a characteristic focal narrowing in the proximal celiac axis. The focal narrowing has a characteristic hooked appearance, which can help distinguish this condition from other causes of celiac artery narrowing, such as atherosclerotic disease.”
  • 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
  • "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
  • "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
  • Inferior Phrenic Artery: Facts

    - arise usually from aorta or celiac axis in most cases. May also arise from the renal arteries
    - IPA is a common source of extrahepatic collateral blood supply for hepatomas
    - IPA may also be involved in hemoptysis, hepatic bleeding or gastroesophageal issues like Mallory Weiss or GE cancer
  • Median Arcuate Ligament Syndrome: Facts

    - AKA celiac artery compression syndrome
    - Median arcuate ligamnet is formed by muscular fibers that connect the left and right crura of the diaphragm
    - May lead to intestinal angina
    - Most patients asymptomatic
    - Pseudo-celiac artery compression may be seen on expiratory phase images
  • "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
© 1999-2017 Elliot K. Fishman, MD, FACR. All rights reserved.