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

Vascular: Thoracic Aorta Imaging Pearls - Educational Tools | CT Scanning | CT Imaging | CT Scan Protocols - CTisus
Imaging Pearls ❯ Vascular ❯ Thoracic aorta

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  • "Given the anatomic complexity of the mediastinum with many adjacent vascular structures, it may be that CR has intrinsic advantages relative to other 3D methods in being able to accurately display the relative positions of those structures in a manner that may be more intuitively grasped in comparison to less photorealistic depictions. At the same time, the shadowing effects produced by CR can potentially obscure important sites of pathology, so a careful inspection of CR visualizations from multiple viewing angles and with multiple different window settings is necessary."
    Evaluation of Kawasaki’s disease-associated coronary artery aneurysms with 3D CT cinematic rendering
    Rowe SP, Zimmerman SL, Johnson PT, Fishman EK
    Emergency Radiology (2018) 25:449–453
  • "Cinematic rendering (CR) is a new 3D post-processing tool that provides even greater anatomic detail than traditional volume rendering. In this case series, CR is used to impart to radiologists a better understanding of various anatomic configurations that can be seen with a ductus diverticulum. "
    MDCT of ductus diverticulum: 3D cinematic rendering to enhance understanding of anatomic configuration and avoid misinterpretation as traumatic aortic injury
    Steven P. Rowe, Pamela T. Johnson, Elliot K. Fishman
    Emergency Radiology (2018) 25:209–213
  • "Among these is the ductus diverticulum—a remnant of the ductus arteriosus that arises from the lesser curvature of the aortic arch, which can be mistaken for a traumatic aortic pseudoaneurysm, dissection, or incomplete rupture. The distal aortic arch, and in particular
    the undersurface, is the most common location for acute traumatic aortic injury. "
    MDCT of ductus diverticulum: 3D cinematic rendering to enhance understanding of anatomic configuration and avoid misinterpretation as traumatic aortic injury
    Steven P. Rowe, Pamela T. Johnson, Elliot K. Fishman
    Emergency Radiology (2018) 25:209–213
  • "Differentiation of a ductus diverticulum from an aortic injury can be difficult, but it is of paramount importance in order to spare patients the morbidity of unnecessary thoracic surgery. This becomes more challenging in the setting of other thoracic traumatic injury, especially mediastinal hematoma, as demonstrated in this case report. Additional cases are also presented to demonstrate the range appearance of the ductus diverticulum using cinematic rendering, a novel method 3D CT visualization method that provides unprece- dented anatomic detail.
    MDCT of ductus diverticulum: 3D cinematic rendering to enhance understanding of anatomic configuration and avoid misinterpretation as traumatic aortic injury
    Steven P. Rowe, Pamela T. Johnson, Elliot K. Fishman
    Emergency Radiology (2018) 25:209–213
  • "However, not all abnormalities of the aorta indicate an acute process, and multiple pitfalls that can mimic acute aortic injury have been described . Among these is the ductus diverticulum—a remnant of the ductus arteriosus that arises from the lesser curvature of the aortic arch, which can be mistaken for a traumatic aortic pseudoaneurysm, dissection, or incomplete rupture. The distal aortic arch, and in particular
    the undersurface, is the most common location for acute traumatic aortic injury. "
    MDCT of ductus diverticulum: 3D cinematic rendering to enhance understanding of anatomic configuration and avoid misinterpretation as traumatic aortic injury
    Steven P. Rowe, Pamela T. Johnson, Elliot K. Fishman
    Emergency Radiology (2018) 25:209–213
  • "Differentiation of a ductus diverticulum from an aortic injury can be difficult, but it is of paramount importance in order to spare patients the morbidity of unnecessary thoracic surgery. This becomes more challenging in the setting of other thoracic traumatic injury, especially mediastinal hematoma, as demonstrated in this case report."
    MDCT of ductus diverticulum: 3D cinematic rendering to enhance understanding of anatomic configuration and avoid misinterpretation as traumatic aortic injury
    Steven P. Rowe, Pamela T. Johnson, Elliot K. Fishman
    Emergency Radiology (2018) 25:209–213
  • "One of the most pronounced advantages of cinematic rendering is the production of realistic shadowing effects, allowing for very clear representation of the relative positions of objects within the imaged volume; this is well demonstrated, where the shadowing from the aortic arch onto the underlying ductus diverticulum and pulmonary arterial vasculature allows the viewer to easily grasp the internal arrangement of these structures."
    MDCT of ductus diverticulum: 3D cinematic rendering to enhance understanding of anatomic configuration and avoid misinterpretation as traumatic aortic injury
    Steven P. Rowe, Pamela T. Johnson, Elliot K. Fishman
    Emergency Radiology (2018) 25:209–213
  • "One of the advantages of volume rendering over maximum intensity projection is the ability to convey 3D anatomic relationships. For complex anatomic configurations like the thoracic aorta and pulmonary arteries, the lighting model in cinematic rendering adds even greater anatomic detail, as demonstrated by these cases."
    MDCT of ductus diverticulum: 3D cinematic rendering to enhance understanding of anatomic configuration and avoid misinterpretation as traumatic aortic injury
    Steven P. Rowe, Pamela T. Johnson, Elliot K. Fishman
    Emergency Radiology (2018) 25:209–213
  • "Cinematic rendering produces volume rendered images with photorealistic image quality. It uses a global illumination model, which takes direct and indirect illumination into account when constructing an image, to achieve rendering quality. The mathematical models that describe this visualization technology include complex integral equations that are solved numerically using the Monte Carlo integration. The result of the integration is a numerical rendering algorithm known as path tracing: thousands of light rays are traced to compute the resulting image."
    MDCT angiography with 3D rendering: A novel cinematic rendering algorithm for enhanced anatomic detail
    Johnson PT, Schneider R, Lugo-Fagundo C, Johnson M, Fishman EK
    AJR 2017 Aug;209(2):309-312
  • "To achieve photorealistic quality an "environment map" or "light map" must be used as this light source provides realistic effects achieved by real world light scenarios. The light map consists of texture maps containing information on the brightness of surfaces in a virtual scene that allow the reproduction of the light environment in which the map was generated."
    MDCT angiography with 3D rendering: A novel cinematic rendering algorithm for enhanced anatomic detail
    Johnson PT, Schneider R, Lugo-Fagundo C, Johnson M, Fishman EK
    AJR 2017 Aug;209(2):309-312
  • "The light model off of which cinematic rendering and classic volume rendering are based when reconstructing the images accounts for the difference between the two technologies. The primary reason why classic volume rendering results in images that are relatively less photorealistic is the use of the local lighting model – only local properties, such as the local gradient, influence the resulting image. Inversely, cinematic rendering assumes the global illumination model, which accounts for the impact that all light rays have on image reproduction."
    MDCT angiography with 3D rendering: A novel cinematic rendering algorithm for enhanced anatomic detail
    Johnson PT, Schneider R, Lugo-Fagundo C, Johnson M, Fishman EK
    AJR 2017 Aug;209(2):309-312
  • "Additionally, cinematic rendering and classic volume rendering differ in their respective light sources. The light sources in classical volume rendering are either single unidirectional light sources or multiple light sources. Although cinematic rendering could use the same light sources as those of classic volume rendering, it also uses environment maps to produce the best visual results. Moreover, classic volume rendering assumes that light passing through the transparent participating medium is absorbed. This assumption leads to less realistic images because in reality light particles are scattered in such a medium. Thus, to achieve photorealism, classic volume rendering would have to account for scattering effects."
    MDCT angiography with 3D rendering: A novel cinematic rendering algorithm for enhanced anatomic detail
    Johnson PT, Schneider R, Lugo-Fagundo C, Johnson M, Fishman EK
    AJR 2017 Aug;209(2):309-312
  • "In cinematic rendering, the most important parameter available to manipulate the resulting image is the transfer function. A parameter that was already available in classic volume rendering, the transfer function assigns a color and an opacity property to each voxel value. The opacity can be zero, one or any number between zero and one. If the opacity is zero, then the voxel value represents a vacuum that does not influence rendering computation. If the opacity is equal to one, then the voxel value represents a region that is fully opaque."
    MDCT angiography with 3D rendering: A novel cinematic rendering algorithm for enhanced anatomic detail
    Johnson PT, Schneider R, Lugo-Fagundo C, Johnson M, Fishman EK
    AJR 2017 Aug;209(2):309-312
  • "The limitations related to cinematic rendering’s photorealistic quality also must be acknowledged. While photorealism improves the image quality and allows for a better perception of structures, it is possible to have scenarios when too much photorealism is bad. For example, if some tissue parts are obstructed from the light source, the tissue becomes darker, which can be very realistic but it can omit information about the vasculature."
    MDCT angiography with 3D rendering: A novel cinematic rendering algorithm for enhanced anatomic detail
    Johnson PT, Schneider R, Lugo-Fagundo C, Johnson M, Fishman EK
    AJR 2017 Aug;209(2):309-312
  • Cinematic Rendering: Future Directions
    ● Implement algorithm on faster hardware or GPU’s
    ● Optimization of lighting models may be possible with AI to select best parameters
    ● Integration into Radiology work flow
  • “ In 6.6% of people, the left vertebral artery arises directly from the arch. The bovine arch is another normal variant in which the left common carotid ar- tery arises from the brachiocephalic trunk rather than the aorta, occurring in up to one-fourth of the population. Although ingrained in the medical literature, the bovine arch is a misnomer for this aortic variant; cows actually have a single brachiocephalic trunk that splits into the bilateral subclavian arteries and a bicarotid trunk.” 


    Computed Tomography Angiography of the Thoracic Aorta 
Scheske JA et al. 
Radiol Clin N Am 54 (2016) 13–33
  • “Another arch variant is the ductus diverticulum, a focal bulge along the inner aspect of the isthmus representing a remnant of the ductus arteriosus. Traumatic aortic transection also occurs in this location and can occasionally be difficult to differentiate from a ductus diverticulum. However, the ductus diverticulum has smooth margins with obtuse angles relative to the adjacent aorta. Aortic transection has irregular margins with acute angles relative to the adjacent aorta.” 


    Computed Tomography Angiography of the Thoracic Aorta 
Scheske JA et al. 
Radiol Clin N Am 54 (2016) 13–33
  • “Acute aortic syndrome is a group of aortic pathol- ogies that are acute emergencies. Underlying aortic diseases include penetrating atherosclerotic ulcer, intramural hematoma, aortic dissection, rupturing aneurysms, and traumatic aortic injury. MDCT is the preferred examination because of its rapid acquisition and excellent depiction of the aorta, its wall, and the end organs. ECG-gated CT is preferred, if readily avail- able, especially if ascending aortic involvement is suspected.” 


    Computed Tomography Angiography of the Thoracic Aorta 
Scheske JA et al. 
Radiol Clin N Am 54 (2016) 13–33
  • “Intramural hematoma (IMH) is hemorrhage local- ized to the aortic media in the absence of a visible intimal tear. IMH is considered equivalent to aortic dissection regarding prognostic and therapeutic implications because an IMH may progress to aortic dissection and rupture. IMH may develop secondary to spontaneous rupture of vasa vasorum of the medial aortic layer, penetrating aortic ulceration, or blunt trauma. Hypertension is the most common predisposing risk factor.” 


    Computed Tomography Angiography of the Thoracic Aorta 
Scheske JA et al. 
Radiol Clin N Am 54 (2016) 13–33
  • “Several findings help differentiate IMH from a thrombosed false lumen of an aortic dissection: IMHs do not enhance; no intimal tear is seen; IMHs maintain a constant circumferential relationship with the aortic wall; the false lumen of a dissection has a longitudinal spiral geometry.Involvement of the ascending aorta, pericardial or pleural effusion, and an aortic diameter of greater than 5 cm may predict progression of an IMH to a true dissection.” 


    Computed Tomography Angiography of the Thoracic Aorta 
Scheske JA et al. 
Radiol Clin N Am 54 (2016) 13–33
  • “Unenhanced CT is extremely valuable in identi- fying intramural hematomas. Typically, circumferential or crescent-shaped high-attenuation thickening of the aortic wall is present, representing hematoma within the medial wall of the aorta , which sometimes narrows the aortic lumen.” 


    Computed Tomography Angiography of the Thoracic Aorta 
Scheske JA et al. 
Radiol Clin N Am 54 (2016) 13–33
    “Penetrating aortic ulcer (PAU) represents an ulcer- ated atheroma disrupting the aortic intima. PAU occurs when an atheromatous plaque ruptures, disrupting the elastic lamina, with variable exten- sion into the media. Hypertension and advanced age are the most common risk factors. The descending aorta is most often affected CT commonly shows extensive aortic atherosclerosis. On CT, a discrete contrast-filled ‘collar button’ is often seen out-pouching beyond the expected confines of the aorta. PAUs are often multifocal, which is not surprising considering the diffuse nature of atherosclerosis.” 


    Computed Tomography Angiography of the Thoracic Aorta 
Scheske JA et al. 
Radiol Clin N Am 54 (2016) 13–33
  • “PAU can be difficult to differentiate from simple ulcerated atherosclerotic plaque. The presence of contour deformity of the vessel is highly suggestive of PAU. Extension of the aortic ulcer into the medial layer can result in an IMH, localized aortic dissection, saccular pseudoaneurysm, or mediastinal hematoma. Invasive intervention (surgery or endovascular repair) should be considered in patients with pain, hemodynamic instability, or signs of aortic expansion. Asymptomatic patients can be followed closely with optimization of medical management. If treated medically, imaging follow-up for both IMH and PAU is recommended at the time of discharge from the hospital, at 1, 3, and 6 months, and then yearly.” 


    Computed Tomography Angiography of the Thoracic Aorta 
Scheske JA et al. 
Radiol Clin N Am 54 (2016) 13–33
  • “The incidence of thoracic aortic aneurysms is currently 10.4 cases per 100,000 persons per year. Affected individuals are most often in their 60s, and men are affected 2 to 4 times more often than women. Hypertension is present in 60% of cases. Thoracic aortic aneurysms are less common than abdominal aortic aneurysms. Up to 25% of patients with thoracic aneurysm will also have an abdominal aortic aneurysm.”

    
Computed Tomography Angiography of the Thoracic Aorta 
Scheske JA et al. 
Radiol Clin N Am 54 (2016) 13–33
  • “Size is the only established risk factor predicting aortic rupture. No significant risk for aortic rupture is associated with aneurysms smaller than 4.0 cm. The risk for aortic rupture increases incrementally with aneurysm size; aneurysms 4.0 to 5.9 cm have a 16% risk for rupture, and those greater than 6.0 cm have a 31% risk for rupture. The average growth rate of thoracic aortic aneurysms is 1.0 mm per year.49 Descending midaortic aneurysms have the fastest growth rate, and ascending aneurysms have the slowest despite larger initial diameter.49 In general, larger aneurysms grow faster. Aneurysms larger than 5.0 cm in diameter grow on average 7.9 mm per year versus 1.7 mm per year for smaller aneurysms.” 


    Computed Tomography Angiography of the Thoracic Aorta 
Scheske JA et al. 
Radiol Clin N Am 54 (2016) 13–33
  • “Aortic root aneurysms may also occur in the setting of bicuspid aortic valves and familial thoracic aortic aneurysm syndrome (FTAAS). Most aneurysms of the tubular ascending aorta are idiopathic but may also occur with bicuspid aortic valve, FTAAS, giant cell arteritis, and syphilis. Nineteen percent of patients with thoracic aneurysms have a family history independent of Marfan or Ehlers-Danlos syndromes.55–58 Bicuspid aortic valve is known to be an independent predictor of ascending aortic aneurysm formation after surgical correction of coarctation.”

    
Computed Tomography Angiography of the Thoracic Aorta 
Scheske JA et al. 
Radiol Clin N Am 54 (2016) 13–33
  • “Surgery is usually recommended for thoracic aortic aneurysms 5.5 cm or greater. Lower thresholds are used in patients with bicuspid aortic valve and genetic and syndromic conditions predisposing to aortic aneurysms. Surgery may be recommended for aneurysms of 5.0 cm or greater or a growth rate greater than 3 mm/y in Marfan syndrome, Turner syndrome, Loeys-Dietz, Ehlers-Danlos, and bicuspid aortic valve or 4.5 cm or greater in the these patients when addi- tional risk factors are present, including family history of aortic dissection, severe aortic regurgitation, or desire for pregnancy.”

    
Computed Tomography Angiography of the Thoracic Aorta 
Scheske JA et al. 
Radiol Clin N Am 54 (2016) 13–33
  • “ Aortic coarctation is focal narrowing of the thoracic aorta, which can occur anywhere in the aorta, although it is most common at the isthmus. Aortic coarctation is a common malformation, affecting men 2 to 5 times more often than women. Aortic coarctation has 3 major subtypes: focal (aortic coarctation), diffuse (hypoplastic isthmus), and complete (aortic arch interruption). The narrowing in aortic coarctation is caused by a fibrous ridge, arising from abnormal hyperplasia of the tunica media. Hemodynamic compromise leads to the development of collaterals to bypass the narrowed aorta. The extent of collaterals depends on the severity of stenosis. Collaterals may compress the spinal cord or may rupture.”


    Computed Tomography Angiography of the Thoracic Aorta 
Scheske JA et al. 
Radiol Clin N Am 54 (2016) 13–33
  • “Aortic coarctations are associated with multiple other abnormalities. Among patients with aortic coarctation, 30% to 40% will also have a bicuspid aortic valve. Patients with Turner syndrome have a higher prevalence of aortic coarctation. Other abnormalities associated with aortic coarctation include ventricular septal defect, patent ductus arteriosus, aortic stenosis, and mitral stenosis. Patients with aortic coarctation must also be evaluated for intracerebral berry aneurysms. Intracerebral aneurysms can rupture, leading to subarachnoid or intracerebral hemorrhage, even long after successful coarctation repair.”


    Computed Tomography Angiography of the Thoracic Aorta 
Scheske JA et al. 
Radiol Clin N Am 54 (2016) 13–33
  • “Aneurysm size is the primary indicator for surgical aortic root repair of asymptomatic aneurysms. In most instances, surgery is indicated for asymptomatic patients without another underlying cardiovascular condition or disease, with aneurysms measuring greater than or equal to 5.5 cm.”

    Pre- and Postoperative Imaging of the Aortic Root 
Hanneman K et al. 
RadioGraphics 2016; 36:19-37
  • “Performing nonenhanced imaging is particularly important in the postoperative setting, as surgical material may be most conspicuous during this phase. Synthetic grafts are usually composed of polyethylene terephthalate and are slightly hyperattenuating on noncontrast CT images relative to the native aortic wall, and are typically visualized as a thin, curvilinear hyperattenuating structure.”

    Pre- and Postoperative Imaging of the Aortic Root 
Hanneman K et al. 
RadioGraphics 2016; 36:19-37
  • “The sinotubular junction is the landmark between the aortic root and the tubular portion of the ascending aorta, and normally forms a waist in the aortic contour between the sinus of Valsalva and the remainder of the ascending aorta. The sinotubular junction is the highest level at which the aortic valve cusps and commissures are attached to the aortic wall.”

    Pre- and Postoperative Imaging of the Aortic Root 
Hanneman K et al. 
RadioGraphics 2016; 36:19-37
  • “Aneurysms of the ascending aorta result most often from cystic medial degeneration. Aortic root enlargement is associated with many underlying conditions including connective tissue disorders such as Marfan syndrome, bicuspid aortic valve, Loeys-Dietz syndrome, hypertension, and atherosclerosis. Less common underlying causes include infections such as syphilis, vasculitides, trauma, and familial thoracic aneurysm disease.” 


    Pre- and Postoperative Imaging of the Aortic Root 
Hanneman K et al. 
RadioGraphics 2016; 36:19-37
  • “Marfan syndrome is an autosomal dominant, inherited connective-tissue disorder that is mainly caused by mutations in the gene (FBN1) that encodes fibrillin-1. Approximately 25% of cases result from a sporadic new mutation in FBN1. Estimates of prevalence are approximately 1 case per 3500–5000 population.” 


    Pre- and Postoperative Imaging of the Aortic Root 
Hanneman K et al. 
RadioGraphics 2016; 36:19-37
  • “Bicuspid aortic valve is the most common congenital cardiac abnormality, with an estimated prevalence of 1%–2%. The inheritance pattern is autosomal dominant with incomplete penetrance. Bicuspid aortic valve shares common histopathologic findings with Marfan syndrome, including cystic medial degeneration, increased levels of matrix metalloproteinases, and decreased levels of fibrillin-1 in the aortic wall. The Sievers classificationof bicuspid aortic valve is based on the number of raphes and the positions of cusps and raphes. Fusion of the right and left coronary cusps is the most common type.” 


    Pre- and Postoperative Imaging of the Aortic Root 
Hanneman K et al. 
RadioGraphics 2016; 36:19-37
  • “Abnormal dilatation of the thoracic aorta has been defined as a diameter greater than 50% above the high end of the normal range .The normal range of aortic diameters depends on age, sex, and body size, as well as on the anatomic segment.The average aortic diameter at the sinuses of Valsalva is 3.0 cm ± 0.5.Thoracic aortic measurements greater than 4 cm are generally considered to be consistent with an aneurysm.”

    Pre- and Postoperative Imaging of the Aortic Root 
Hanneman K et al. 
RadioGraphics 2016; 36:19-37
  • “In most instances, surgery is indicated for asymptomatic patients without another underlying cardiovascular condition or disease, with aneurysms measuring greater than or equal to 5.5 cm. The risk of aortic dissection or rupture at diameters above 5.5 cm is generally perceived to exceed the risk of operation, warranting intervention. In patients with evidence of rapid aortic growth (>0.5–1 cm per year), elective surgical interven- tion should also be considered even if absolute size criteria have not been met.” 


    Pre- and Postoperative Imaging of the Aortic Root 
Hanneman K et al. 
RadioGraphics 2016; 36:19-37
  • Aortic Dissection:
    Complications
    - Aortic rupture
    - Pericardial tamponade
    - End organ ischemia
    - Over time, false lumen can dilate resulting aneurysm formation
  • Penetrating Atherosclerotic Ulcer
    Complications:
    - Aneurysm
    - Pseudoaneurysm
    - Dissection
    - Rupture
    Management:
    - Rupture risk relates to aortic size
    - Repair if symptomatic
    - Consider repair for larger PAU
  • Post-Processing
    - Multiplanar images
    - Maximum intensity projection (MIP)
    - Volume rendered images
    - Curved planar reformatted (centerline) images for most accurate and reproducible measurements of aortic diameter
  • Endovascular aneurysm repair (EVAR)
    - Exclude aneurysm from blood flow by placing internal stent

    Open repair:
    - Resect the aneurysm
    - Interposition graft (Dacron)
    - Valve replacement (composite) or valve sparing in thoracic aorta
  • Aortic Pathology
    - Aneurysm
    - Dissection
    - Intramural hematoma
    - Pseudoaneurysm
    - Penetrating ulcer
  • Aortic Measurements
    - Midascending thoracic aorta: < 4 cm
    - Descending thoracic aorta: < 3 cm
    - Abdominal aorta:
    - < 3 cm proximally
    - Tapers to 2.5 cm distally
  • Aneurysm Measurement
    - Axial measurements prone to error
    - dilated aorta tortuous
    - Multiplanar interpretation~standard of care
    - measure orthogonal to aortic centerline 
    - New centerline software tools
    - Semiautomated
    - Curved planar reformat
    - Improved reproducibility
  • Thoracic Aortic Aneurysm
    - Atherosclerosis (smoking, hypertension)
    - Collagen vascular disease
    - Marfan Syndrome
    - Loeys Dietz
    - Vascular Ehlers Danlos
    - Dissection
    - Bicuspid aortic valve
  • TAA: Complications
    - Rupture- risk relates directly to size
    - Dissection
    - Aortic regurgitation
    - Compression of adjacent mediastinal structures
    - Concomitant coronary artery disease
  • TAA: Repair
    - Surgical thresholds
    - 5.5 cm ascending aorta
    - 6.5 cm descending aorta
    - Lower thresholds in patients with genetic syndromes
    - Marfan, Loeys-Dietz and Vascular Ehlers Danlos (Type IV) Syndromes
    - Increased risk of dissection and rupture
  • Dissection: Classification
    - DeBakey
    - 1: ascending aorta, arch and beyond
    - 2: ascending aorta only
    - 3: descending aorta only
    - Stanford
    - A: ascending aorta propogation
    - B: no ascending aorta propogation
  • Dissection: Complications
    - End organ ischemia
    - Pericardial tamponade
    - Aortic rupture
    - Over time, false lumen dilates
    - Descending thoracic/abdominal aortic  aneurysm
  • Intramural Hematoma
    - Management varies according to location (ascending vs descending aorta)
    - Many advocate surgery for ascending aortic involvement similar to aortic dissection management
    - Others support “timely surgery” for those who progress or develop complications
  • Follow up IMH
    - Generally decrease in size or resolve
    - May progress to other aortic pathology
    - Fusiform aortic aneurysm
    - Dissection
    - Development of ulcer-like projections
  • AA IMH Observation
    - Hemodyamically stable, no persistent pain
    - Aorta - 50 mm
    - Hematoma - 10 mm thick
    - No penetrating atherosclerotic ulcer
    - No ulcer-like projection
    - Small effusions
    - No aortic insufficiency
    - Aortic diameter > 50 mm
    - IMH thickness > 10 mm
    - Tamponade
  • Indications for Timed Surgery
    - Pain
    - New ulcer-like projection
    - Progression to aortic dissection
    - Increasing IMH thickness
    - Increasing aortic diameter
  • - Increasing effusion- Tamponade
    - Aortic branch artery pseudoaneurysms
    - Lumbar or intercostal artery orifice
    - Contrast filled pool inside the IMH
    - Communication w/ lumen < 2 mm or absent
    - Do not mistake for ulce
  • Aortic Pseudoaneurysm
    - Contained rupture of the aortic wall
    - Saccular protrusions
    - Varying degrees of mural thrombus
    - Life-threatening emergency at risk of rupture
  • Penetrating Ulcer
    - Underlying atherosclerotic disease
    - Ulcer within plaque is confined to intima
    - Penetrating ulcer erodes from the intima through the internal elastic lamina
    - Extends into media causing hematoma
    - 80% have intramural hematoma
  • Penetrating Ulcer
    - Complications:
    - Aneurysm
    - Pseudoaneurysm
    - Dissection
    - Rupture
    - Rupture risk relates to aortic size
  • Aortic Repair
    - Endoluminal stent placement
    - Abdominal aortic stent grafts
    - Thoracic aortic stent grafts
    - Surgical endograft
    - Aortic root/ascending aorta
    - Extensive aortic pathology
    - Necessitates staged repair
  • Thoracic Aortic Segments
    - Ascending thoracic aorta
    - Select patients only
    - Nonsurgical candidates
    - Experienced centers
    - Aortic arch
    - Complicated: arch curvature, branches
    - Fenestrated, branched grafts
    - Descending thoracic aorta (DTA)
  • Severe Aortic Calcification or “Porcelain Aorta”
    - “ Severe aortic calcification (“porcelain aorta”) is a clinically significant preoperative finding indicating that the aortic valve replacement surgery may be technically difficult or impossible. Aortotomy, cross clamping, cannulation, and suturing are more likely to cause embolic phenomena, aortic dissection, mural laceration and hemorrhage in the presence of severe calcification.”
  • “ Severe aortic calcification (“porcelain aorta”) is a clinically significant preoperative finding indicating that the aortic valve replacement surgery may be technically difficult or impossible. Aortotomy, cross clamping, cannulation, and suturing are more likely to cause embolic phenomena, aortic dissection, mural laceration and hemorrhage in the presence of severe calcification.”
    CT and MR Imaging of the Aortic Valve: Radiologic –Pathologic Correlation
     Bennett CJ et al.
    RadioGraphics 2012;32:1399-1420
  • “ Unenhanced CT performed well in detection of acute aortic syndrome treated surgically, although its performance does not support its use in place of contrast enhanced CTA. Unenhanced CT may be a reasonable first examination for rapid triage when IV contrast is contraindicated.”
    Acute Aortic Syndromes: A Second Look at Dual-Phase CT
    Lovy AJ et al.
    AJR 2013; 200:805-811
  • “ Contrast-enhanced CTA was highly sensitive for intramural hematoma, suggesting that unenhanced imaging may not always be needed. Acute aortic syndrome imaging protocols should be optimized to reduce radiation dose.”
    Acute Aortic Syndromes: A Second Look at Dual-Phase CT
    Lovy AJ et al.
    AJR 2013; 200:805-811
  • Acute Aortic Syndrome
    - Aortic dissection
    - Intramural hematoma
    - Penetrating atherosclerotic ulcer
    - Ruptured aortic aneurysm
  • “ Intramural blood pools (IBP) are frequently observed at multidetector CT in patients with intramural hematoma (IMH). They may resolve over time or appear during follow-up. These findings are not associated with a poor prognosis, and IBPs should be distinguished from ulcer like projections.”
    Intramural Blood Pools Accompanying Aortic Intramural Hematoma: CT Appearance and Natural Course
    Wu MT et al.
    Radiology 2011;258:705-713
  • “ Intramural blood pools (IBP) is an intramural contrast medium filled pool with a tiny intimal orifice and/or a connection with an intercostal or lumbar artery in an IMH; IBP is morphologically distinct from an ulcer like projection (ULP) which has a wiser intimal opening to the lumen.”
    Intramural Blood Pools Accompanying Aortic Intramural Hematoma: CT Appearance and Natural Course
    Wu MT et al.
    Radiology 2011;258:705-713
  • “ Most Intramural blood pools (IBP) show complete resorption over time (32 of 56 (57%) or have incomplete resorption (16 of 56 (29%) during a median follow-up of 33.8 months; the presence of IBP was not associated with poor prognosis.”
    Intramural Blood Pools Accompanying Aortic Intramural Hematoma: CT Appearance and Natural Course
    Wu MT et al.
    Radiology 2011;258:705-713
  • Aortic Transection: Facts
    - 10-20% of patients survive the initial event
    - Occurs most commonly at aortic isthmus (space between brachiocephalic trunk and that of the ligamentum arteriosus)
    - Mediastinal hematoma (anterior of posterior mediastinum) is common but not diagnostic of aortic injury
    - Hematoma of interest most commonly around the aorta
  • Aortic Transection: Facts
    - The direct signs of aortic transection include;
    - Vessel caliber change
    - Pseudoaneurysm
    - Intramural flap
  • Cardiac Trauma: Differential Diagnosis
    - Aortic transection
    - Valvular rupture
    - Hemopericardium
    - Cardiac tamponade
  • “ The “panscan” (computed tomographic (CT) examination of the head, neck, chest, abdomen, and pelvis) has become an essential element in the early evaluation and decision making algorithm for hemodynamically stable patients who sustained abdominal trauma.”
    Multidetector CT of Blunt Abdominal Trauma: State of the Art
    Soto JA, Anderson SW
    Radiology 2012;265:678-693
  • “ In patients with hemoperitoneum, the presence of active extravasation and the rate of bleeding have a more direct effect on patient care decisions than does the volume of free fluid in the abdomen.”
    Multidetector CT of Blunt Abdominal Trauma: State of the Art
    Soto JA, Anderson SW
    Radiology 2012;265:678-693
  • TAA: Complications
    - Rupture- risk relates directly to size
    - Dissection
    - Aortic regurgitation
    - Compression of adjacent mediastinal structures
    - Concomitant coronary artery disease
  • TAA: Repair
    - Surgical thresholds
    - 5.5 cm ascending aorta
    - 6.5 cm descending aorta
    - Lower thresholds in patients with genetic syndromes
    - Marfans syndrome, Loeys-Dietz syndrome
    - Increased risk of dissection and rupture
  • Genetic Syndromes: Repair
    - Aortic root or ascending aorta > 5 cm OR rate of enlargement > 0.5 cm per year
    - For those who need aortic valve replacement, root or ascending aorta repair if > 4.5 cm
    - Smaller patients have lower thresholds
    - Counsel patients considering pregnancy at size of 4.0 to 4.5 cm
    - LDS patients – repair at 4.5 cm
  • TEVAR: Role of Radiologist
    - Thoracic Endovascular Aortic Repair
    - Determine patient is a candidate for TEVAR
    - Perform critical pre-procedural analyses
    - Location and extent of the pathology
    - Requirement for branch vessel occlusion
    - Risk of spinal cord ischemia
    - Identify risk factors for deployment failure
    - Angulation of the aorta and run-off vessels
    - Provide information to guide stent selection 
  • Ascending Aorta IMH Mgt
    - Criteria for Observation
    - Hemodyamically stable, no persistent pain
    - Aorta - 50 mm
    - Hematoma - 10 mm thick
    - No penetrating atherosclerotic ulcer
    - No ulcer-like projection
    - Small effusions
    - No aortic insufficiency
  • Ascending Aorta IMH Mgt
    - Criteria for Observation
    - Hemodyamically stable, no persistent pain
    - Aorta - 50 mm
    - Hematoma - 10 mm thick
    - No penetrating atherosclerotic ulcer
    - No ulcer-like projection
    - Small effusions
    - No aortic insufficiency
  • Ascending Aorta IMH Mgt
    - Criteria for “timed” surgery
    - Pain
    - New ulcer-like projection
    - Progression to aortic dissection
    - Increasing IMH thickness
    - Increasing aortic diameter
    - Increasing effusion
    - Tamponade
  • Penetrating Ulcer
    - Underlying atherosclerotic disease
    - Atheromatous plaques erode and penetrate internal elastic lamina
    - 80% have intramural hematoma
  • Penetrating Ulcer
    - Complications:
    - Aneurysm
    - Pseudoaneurysm
    - Dissection
    - Rupture
    - Rupture risk relates to aortic size
  • Aortic Dissection: Causes
    - Hypertension
    - Collagen vascular disease
    - Genetic vascular syndromes
    - Marfans, Loeys-Dietz, Ehlers Danlos
    - Trauma
    - Iatrogenic
    - Cardiac surgery
    - Penetrating ulcer
    - Bicuspid aortic valve
  • Dissection: Classification
    - DeBakey
    - 1: ascending aorta, arch and beyond
    - 2: ascending aorta only
    - 3: descending aorta only
    - Stanford
    - A: ascending aorta propogation
    - B: no ascending aorta propogation
  • TAD: Complications
    - Aortic rupture
    - Pericardial tamponade
    - End organ ischemia
    - Over time, false lumen can dilate resulting aneurysm formation
  • Retrograde Type A Dissection:
    Risk Factors
    1. Graft
    - those with proximal bare springs
    2. Aorta
    - steeply angulated aortic arch in the setting of a morphologically normal aorta
    3. Both
    - compliance mismatch between the stent graft and aortic wall
  • Operative Aortic Repair
    - Abdominal aortic graft instability
    - Aortic root repair
    - Extensive aortic pathology and staged repair
  • Post Surgical Repair
    - Comparative series of 1252 patients repaired with endoluminal stents and surgical grafts followed for up to 10 years reported rupture only after endovascular treatment.
    - Following surgical repair, the rate of anastomotic pseudoaneurysm formation (contained rupture) is 0.2-15%
  • Post Surgical Repair
    1. Surgical grafts dilate over time, rates depending on the graft material (ePTFE vs polyester).
    - At 6 years, dilatation ranges between 20-30%
    - ePTFE exhibits lowest degree of dilatation
    - Dilatation does not result in graft failure
    2. Grafts lose strength over time, owing to polyester degradation.
    - 31.4% lost at 10 years
    - 100% lost at 25-39 years
  • Aortic Root Repair
    1. Must know surgical procedure
    - valve may be replaced
    - coronary reimplantation or bypass
    2. Full root interposition
    - Excision and end-to-end anastomoses
    3. Inclusion root technique
    - Native root wrapped around graft
  • Complications
    1. Vascular
    - pseudoaneurysm
    - coronary ostial aneurysm
    - dissection
    - endoleak
    2. Periaortic   
    - mediastinitis
    - sternal dehiscence
  • Extensive Aortic Pathology
    1. Pathology that involves ascending aorta, aortic arch, descending aorta
    - +/- abdominal aorta
    2. Necessitates staged repair
    3. Stage 1:
    - Ascending aortic graft   
    - Elephant trunk prosthesis arch/proximal descending thoracic aorta
    4. Stage 2:
    - Descending aorta +/- abdominal aorta repair
  • Ductus Aneurysm: Facts
    - Most common mechanism is failure of closure of the aortic side of the ductus arteriosus
    - In adults may present with cough, dyspnea, or dysphonia
    - Can be confused with traumatic aneurysm of the aorta but that is usually located in the posterior part of the arch distal to the origin of the left subclavian artery
    - Calcifications are not uncommon in ductus aneurysms
  • “Aneurysm of the ductus arteriosus is a very rare congenital lesion in adults that can be associated with thromboembolism, rupture, and death. Its detection in a silent clinical phase is very important for planning appropriate treatment and avoiding potentially fatal complications.”
    Incidental detection of a giant ductus arteriosus aneurysm by low-dose multidetector computed tomography in an asymptomatic adult
    Pontone G et al.
    J Vasc Surg Vol 5;5 pg 1260-1264 May 2010
  • “Thoracic endovascular aortic repair (TEVAR) has evolved as an alternative to open repair for a range of aortic pathology. The earliest endovascular repairs were limited to descending thoracic aortic pathology, but growing experience has resulted in the use of stents in the ascending aorta and aortic arch. This review presents the current literature pertaining to thoracic endoluminal stent repair, with emphasis on the role of intravenous contrast-enhanced multidetector computed tomography, the primary cross-sectional imaging modality used in these patients. Radiologists play an integral role in patient selection, procedural planning, and postprocedural follow-up.”
    Thoracic endovascular aortic repair: literature review with emphasis on the role of multidetector computed tomography
    Johnson PT, Black JH, Zimmerman SL, Fishman EK
    Semin Ultrasound CT MR 2012 Jun; 33(3):247-64
  • “This review presents the current literature pertaining to thoracic endoluminal stent repair, with emphasis on the role of intravenous contrast-enhanced multidetector computed tomography, the primary cross-sectional imaging modality used in these patients. Radiologists play an integral role in patient selection, procedural planning, and postprocedural follow-up.”
    Thoracic endovascular aortic repair: literature review with emphasis on the role of multidetector computed tomography
    Johnson PT, Black JH, Zimmerman SL, Fishman EK
    Semin Ultrasound CT MR 2012 Jun; 33(3):247-64
  • “ MDCT with virtual angioscopy can depict the configuration of intimal tears in cases of thoracic aortic dissection, which may facilitate therapeutic planning.”
    Intimal Tears in Thoracic Aortic Dissection: Appearance on MDCT With Virtual Angioscopy
    Maldjiian PD eta l.
    AJR 2012; 198:955-961
  • “MDCT can depict feature helping to differentiate the true lumen from the false lumen. The false lumen is usually larger than the true lumen and commonly deforms the shape of the true lumen.”
    Intimal Tears in Thoracic Aortic Dissection: Appearance on MDCT With Virtual Angioscopy
    Maldjiian PD eta l.
    AJR 2012; 198:955-961
  • “Flow in the false lumen is usually slower than that in the true lumen; hence the attenuation of the false lumen tends to be lower and more heterogeneous than the attenuation of the true lumen because of mixing of contrast agent with unopacified blood.”
    Intimal Tears in Thoracic Aortic Dissection: Appearance on MDCT With Virtual Angioscopy
    Maldjiian PD eta l.
    AJR 2012; 198:955-961
  • “ Imaging of the thoracoabdominal aorta with ECG-triggered high-pitch CTA provides higher quality images of the aortic root and ascending aorta with sufficient contrast enhancement and decreased estimated radiation dose compared with non-ECG-synchronized standard pitch CT.”
    Image Quality, Contrast Enhancement, and Radiation Dose of ECG-Triggered High Pitch CT Versus Non-ECG-Triggered Standard-Pitch CT of the Thoracoabdominal Aorta
    Bolen MA et al.
    AJR 2012;198:931-938

  • Persistent Left SVC: Facts

    - Represents persistence of the left common cardinal vein
    - Usually drains into the coronary sinus
    - Usually associated with absent left brachiocephalic vein
    - Usually has SVC present as well
    - Occurs in 0.2-0.4% of patients
  • Persistent Left SVC: Facts
    - Represents persistence of the left common cardinal vein
    -Usually drains into the coronary sinus
    - Usually associated with absent left brachiocephalic vein
    - Usually has SVC present as well
    - Occurs in 0.2-0.4% of patients
  • Collateral pathways are commonly opacified in SVC Syndrome
    - Azygous and hemiazygous system
    - Paravertebral vessels
    - Mediastinal veins as collaterals (as in this case)
    - Anterior intercostal veins
    - Internal mammary veins
  • “C” - Double aortic arch
    -    Rare anomaly caused by persistence (to varying degree) of the fetal double aortic arch
    system.
    -    The ascending aorta divides into two arches that pass to either side of the esophagus and
    trachea and reunite to form the descending aorta.
    -    Form of complete vascular ring, resulting in noncardiac morbidity, but rarely associated
    with intracardiac defects.
    -    The descending aorta is usually on the left side.
    -    Most commonly, one arch is dominant, whereas the other may be of small caliber or
    represented by a fibrous band
  • “A” - Right AA with mirror image branching
        The mirror-image type of the right aortic arch (left brachiocephalic trunk, right common
    carotid and subclavian arteries) is almost always associated with congenital heart disease,
    especially the cyanotic type.
  • “B” - Right AA with aberrant left subclavian artery
    -Right aortic arch is an uncommon anatomical anomaly that occurs in <0.1% of the population.
    -The most common type is the right aortic arch with an aberrant left subclavian artery
    -The vessels originate in the following order: left common carotid, right common carotid, right subclavian, and left subclavian artery.
    -Symptoms may arise from vascular ring formation as congenital heart disease is rare in this variant.
  • “D” - Left AA with aberrant right subclavian artery
    -    The right subclavian artery is the last branch of the aortic arch in l% of individuals.
    -    It courses to the right behind the esophagus in 80% of these cases, between the esophagus
    and trachea in 15%, and anterior to the trachea or mainstem bronchus in 5%.
    -    A retroesophageal course may be the cause of so-called dysphagia lusoria.
    -    Another variant - aberrant right brachiocephalic artery is rare
  • Classification:
    -    Double aortic arch
    -    Right arch dominant
    -    Left arch dominant
    -    Balanced arches
    -    Right aortic arch–left ligamentum
    -    Mirror-image branching
    -    Retroesophageal left subclavian artery
    -    Circumflex aorta
    -    Pulmonary artery sling
  • Vascular Ring Hierarchy
    -    If abnormal combination of derivatives of the aortic arch system results in encirclement of
    the trachea and the esophagus it is often referred to as “vascular ring”.
    -    International Congeital Heart Surgery Nomenclature And Database Committee
  • Normal Anatomy
    -    Predominant human anatomy is a left aortic arch with three great vessels; first, the
    brachiocephalic trunk, then the left common carotid artery and finally the subclavian artery.
    This pattern occurs in 65-80% of the cases.
    -    A common brachiocephalic trunk, so-called “bovine trunk”, in which both common carotid
    arteries and the right subclavian artery arise from a single trunk off the arch, occurs in 10 to
    22% of individuals and accounts for more than two thirds of all arch vessel anomalies.
  • Abdominal Aorta Prestent
    -Need 1.0-1.5 cm distance between proximal landing zone and renal aa
    -Infrarenal neck 
    -Neck angulation 
  • Thoracic Aorta Prestent
    -Need at least 1 cm normal aortic wall between landing zone and major branch
    -Diameter of proximal and distal aortic necks
    -Diameter of femoral and iliac arteries
  • Stent Planning
    -Describe aneurysm
    -Size both diameter and length
    -Location
    -Distance of aneurysm from branch vessels

    Impediments to stent placement
    -Femoral or iliac a small caliber or stenoses
    -Severe aortoiliac tortuousity
  • Aortic Surgery
    -First successful surgical repair was in 1951 using a cadaver graft
    -Prior to this, techniques included cellophane wrapping and ligation
  • Aortic Repair
    -Surgical endograft
    -Surgical bypass graft
    -Endoluminal stent placement
  • Aortic Dissection:

    Complications
    -Aortic rupture
    -Pericardial tamponade
    -End organ ischemia
    -Over time, false lumen can dilate resulting in aneurysm formation
  • Aortic Dissection: Classification

    DeBakey
    -1: ascending aorta, arch and beyond
    -2: ascending aorta only
    -3: descending aorta only

    Stanford
    -A: ascending aorta propogation
    -B: no ascending aorta propogation
  • Aortic Dissection Causes
    -Aneurysm
    -Hypertension
    -Trauma
    -Iatrogenic
    -Collagen vascular disease
    -Cardiac surgery
    -Penetrating ulcer
    -Bicuspid or replaced aortic valve
  • Penetrating Ulcer

    Complications:
    -Aneurysm
    -Pseudoaneurysm
    -Dissection
    -Rupture

    Rupture risk relates to aortic size
  • Penetrating Ulcer
    -Underlying atherosclerotic disease
    -Atheromatous plaques erode and penetrate internal elastic lamina
    -80% have intramural hematoma
  • F/U Intramural Hematoma

    Generally decrease in size or resolve

    May progress to other aortic pathology
    -Fusiform aortic aneurysm
    -Dissection
    -Development of ulcer-like projections
  • Ascending Thoracic Aorta Intramural Hematoma Mgt

    Criteria for Observation
    -Hemodyamically stable
    -No persistent pain
    -Aorta less than or equal to 50 mm
    -Hematoma less than or equal to 10 mm thick
    -No PAU or ULP
    -Small effusions
    -No aortic insufficiency
       
    Criteria for “timed” surgery
    -Pain
    -New ULP
    -Progression to AD
    -Increasing IMH thickness
    -Increasing aortic diameter
    -Increasing effusion
    -Tamponade
    -No regression
  • Intramural Hematoma
    -Management varies according to location (ascending vs descending aorta)
    -Many advocate surgery for ascending aortic involvement or “timely surgery”
  • Thoracic Aortic Pseudoaneurysm
    -Sequela of cardiac surgery
    -Ascending aorta most common location
    -Arise from surgically manipulated locations
    --proximal valve graft anastomosis
    --distal aortic anastomosis
    --coronary button reimplantation
    --vein graft anastomosis
  • Draped Aorta Sign

    Contained rupture

    Posterior wall of aorta
    -not identifiable as distinct from adjacent structures 
    -closely follows the contour of adjacent vertebral bodies
  • Aneurysm Instability

    Impending rupture
    - Crescent sign

    Contained rupture
    - Draped aorta sign
  • Aneurysm Growth Rate

    Mean expansion rate is 2.6 -3.6 mm/yr
    - Most grow 1-4 mm/year
    - Growth rate directly correlates with size

    Aneurysms that enlarge rapidly are at risk for rupture
  • Abdominal Aortic Aneurysm
    - Larger than 3 cm
    - 4 - 5.4 cm can be monitored
    - Fusiform > 5.4 cm warrants repair
  • TAA: Complications
    - Rupture- risk relates directly to size
    - 5.5 cm as surgical threshold for ascending
    - 6.5 cm as surgical threshold for descending
    - Dissection
    - Aortic regurgitation
    - Compression of adjacent mediastinal structures
    - Concomitant coronary artery disease
  • Aortic Measurements

    Midascending aorta: < 4 cm

    Descending aorta: < 3 cm

    Abdominal aorta:
    - < 3 cm proximally
    - Tapers to 2.5 cm distally

    Enlarges normally with age

    Slight difference between systole & diastole (< 2 mm)

     

  • "Most IBPs show complete resorption over time (32 of 56 957%) or have incmplete resorption (16 of 56 (29%) during a median follow-up of 33.8 months: the presence of IBP was not associated with poor prognosis."

    Intramural Blood Pools Accompanying Aortic Intramural hematoma: CT Appearance and Natural Course Wu MT et al. Radiology 2011;258:705-713

  • "IBP is an intramural contrast medium filled pool with a tiny intimal orifice and/or a connection with an intercostal or lumbar artery in a IMH: IBP is morphologically distinct from an ulcerlike projection (ULP) which has a wider intimal opening to the lumen."

    Intramural Blood Pools Accompanying Aortic Intramural hematoma: CT Appearance and Natural Course
    Wu MT et al.
    Radiology 2011;258:705-713

  • "In patients with aortic IMH, IBP is not an uncommom finding: IBP is associated with a relatively benign clinical course that shows complete resorption or stability in most patients (86%)."

    Intramural Blood Pools Accompanying Aortic Intramural hematoma: CT Appearance and Natural Course
    Wu MT et al.
    Radiology 2011;258:705-713

  • "Intramural blood pools (IBP) are frequently observed at multidetector CT in patients with intramural hematoma (IMH). They may resolve over time or appear during follow-up. These findings are not associated with a poor prognosis, and IBPs should be distinguished from ulcerlike projections."

    Intramural Blood Pools Accompanying Aortic Intramural hematoma: CT Appearance and Natural Course
    Wu MT et al.
    Radiology 2011;258:705-713

  • Aortic Arch Vessel Mapping

    "Given the widespread availability as well as the ease of acquiring CTA in the trauma setting, CTA is increasingly being used as the initial diagnostic evaluation in extremity vascular trauma, replacing digital subtraction angiography in many institutions."

    Extremity CT Angiography: Application to trauma using 64-MDCT
    Sah N et al.
    Emerg Radiol (2009) 16;425-432

  • Aortic Arch Vessel Mapping

    "A total of 65.9% of patients had both normal aortic arch branching patterns and normal venous anatomy. Variants in the aortic arch branching pattern were present in 32.4% and anomalies in 1.5%. Venous anomalies were present in 0.7%."

    Variants and Anomalies of Thoracic Vasculature on Computed Tomographic Angiography in Adults
    Berko NS et al.
    J Comput Assist Tomogr 2009;33: 523-528

  • Vascular: Aortic Arch Vessel Mapping
    - Normal arch branching seen in 65% of cases ( separate origins of brachiocephalic, left common carotid, left subclavian)
    - Bovine arch branching is seen in 27% of cases (common origin of brachiocephalic and left carotid artery)
    - Other variations are seen in 8% of cases and include left vertebral artery off the arch, right aortic arch, aberrant right subclavian artery)
  • Stanford Type A Dissection
    - Involves ascending aorta and may extend into the descending aorta
    - Account for 60-70% of cases
    - Requires surgical intervention
    - Mortality rate of up to 50% at 48 hours if untreated

    - Involves the descending aorta distal to the left subclavian artery
    - Accounts for 30-40% of cases
    - Usually managed conservatively
    - Surgery required including ruptured aorta, aneurysm over 6 cm, poor perfusion of mesenteric vessels or renal arteries, distal embolization
  • "Multidetector CT allows the early recognition and characterization of aortic dissection as well as determination of the presence of any associated complications, findings that are essential for optimizing treatment and improving clinical outcomes."

    Multidetector CT of Aortic Dissection: A Pictorial Review
    McMahon MA, Squirrell CA
    RadioGraphics 2010; 30:445-460

  • Why do we gate evaluation of the thoracic aorta?
    - Quality evaluation of the entire thoracic aorta including the aortic sinus and aortic valve
    - Definition of the coronary arteries especially in the proximal portions of the coronaary vessels
  • "Optimal image quality for either technique is obtained with a relatively slow heart rate, which may require beta-blocker medication."

    Prospective and Retrospective ECG Gating for Thoracic CT Angiography: A Comparitive Study
    Wu W et al.
    AJR 2009;193:955-963

  • "Compared with retrospective ECG-gated thoracic CT angiography, prospective ECG-gated thoracic CT angiography was associated with a lower radiation dose, slightly increased contrast load, increased aortic attenuation values, and equivalent image quality."

    Prospective and Retrospective ECG Gating for Thoracic CT Angiography: A Comparitive Study
    Wu W et al.
    AJR 2009;193:955-963

  • Takayasu Arteritis: Numano Classification
    - Type I: involvement of only the branches of the aortic arch
    - Type IIA: involvement of the ascending aorta or the aortic arch with or without branches
    - Type IIB: involvement of the descending thoracic aorta with or without the ascending aorta or the aortic arch with its branches
    - Type III: involvement of the entire descending aorta with or without the renal arteries

    - Type IV: involvement of only the abdominal aorta with or without the renal arteries
    - Type V: involvement of the entire aorta with branches Involvement of the coronary arteries or the pulmonary arteries is indicated with a C(+) or P(+) respectively
  • Takayasu Arteritis: Facts
    - Large vessel arteritis that affects aorta and its branches
    - Affects woman and young girls most commonly (80-90% are female in second and third decade of life)
    - Circumferential wall thickening is earliest finding
    - Treatment includes steroids or immunosuppressive therapy as well as surgical revascularization of sites of involvement
  • Marfans Syndrome: Surgery
    - Ascending aorta 45 mm or growing greater than 0.5 cm/yr is indication for surgery
    - Repair is of root , aortic valve and ascending aorta
  • Marfans Syndrome: Cardiovascular Findings
    Minor Criteria
    - Dilatation or dissection of the descending or abdominal aorta before the age of 50 years
    - Dilatation of the main pulmonary artery before age 40

    - Mitral valve prolapse
    - Calcification of the mitral valve before age 40
  • Marfans Syndrome: Cardiovascular Findings
    Major Criteria 
    - Dilatation of the ascending aorta involving at least the sinuses of Valsalva with or without aortic regurgitation
    - Dissection of the ascending aorta
  • Ghent Criteria: Major and Minor Findings
    - 2 major and 1 minor criteria 

    or

    - 1 major and 4 minor criteria 
  • Marfan Syndrome: Facts
    - Autosomal dominant
    - Caused by mutations in the fibrillin-1 gene (FBN1) on chromosome 15
    - Diagnosis based on Ghent criteria which include cardiovascular, ocular, and pulmonary abnormalities
    - Average age of death in untreated patients is 35 years while in treated patients up to age 75 years
  • Supravalvular Aortic Stenosis: facts
    - Focal or diffuse narrowing of the aorta starting at the sinotubular junction and often involves the entire ascending aorta
    - SVAS may be associated with Williams-Beuren syndrome which is an autosomal dominant multisystematic disorder that may manifest with SVAS (71% of cases), mitral valve prolapse and pulmonary artery stenosis
  • Coarctation of the Aorta: Facts
    - Male predominance (1.5:1)
    - Aortic narrowing in region of ligamentum arteriosum just distal to the left subclavian artery
    - Solitary lesion in 82% of cases but can be associated with Turner syndrome, bicuspid aortic valve, intracranial aneurysms, VSD and ASD defects, and Shone complex (left ventricular outflow tract obstruction and parachute mitral valve)
  • Acute Aortic Syndrome Includes;
    • Penetrating atherosclerotic ulcer
    • Acute thoracic aortic injury
    • Intramural hematoma
    • Dissection
    • Aneurysmal leakage
  • Thoracic Endovascular Stents: Endoleaks
    - Type I: these result from incomplete seal of the ends of the stent to the aortic wall
    - Type II: result from retrograde flow of blood into excluded lumen from patent branch vessels of the aorta
    - Type III: result from junctional dehiscence or device degeneration
    - Type IV: result from porosity of the stent
    - Type V: are increase in size of excluded lumen w/o enhancement in excluded lumen
  • Thoracic Endovascular Stents: Endoleaks
    - Occur in up to 29% of cases
    - Five types of endoleaks occur
    - Type I account for 40% of all endoleaks
  • Thoracic Endovascular Stents: Complications
    - Collapse of stent
    - Migration of stent
    - Endoleak
    - Pseudoaneurysm or dissection
    - Pulmonary embolism
  • Thoracic Endovascular Stents:Indications
    - Aortic aneurysms
    - Acute and chronic dissection
    - Penetrating ulcer
    - Intramural hematoma
    - Traumatic aortic rupture
  • Complications of Endovascular Stent Placement
    • Endoleaks
    • Stent migration
    • Pseudoaneurysms
    • Dissection
    • Aortic perforation
    • Kinking
    • Thrombosis
    • Coverage of key arch vessels
  • "Postprocedure multidetector CT is mandatory to assess stent placement, efficacy, and complications. Important factors to document are location of the stent, stent patency, size of the aorta, thrombosis of disease outside the aortic lumen, and any complications."


    Thoracic Aortic Stent-Grafts: Utility of Multidetector CT for Pre- and Postprocedure Evaluation
    Bean MJ, Johnson PT, Roseborough GS, Black JH, Fishman EK
    RadioGraphics2008; 28:1835-1851

  • "In this article, we discuss which patients are potential candidates for thoracic aortic stent graft placement and demonstrate how multidetector computed tomography with two dimensional multiplanar reformation (MPR) and three dimensional rendering (3D) is relevant in preoperative imaging and post operative assessment of thoracic stent grafts."


    Thoracic Aortic Stent-Grafts: Utility of Multidetector CT for Pre- and Postprocedure Evaluation
    Bean MJ, Johnson PT, Roseborough GS, Black JH, Fishman EK
    RadioGraphics2008; 28:1835-1851

  • Thoracic Endovascular Stent Placement: Patient Selection
    • Penetrating ulcers
    • Aortic aneurysm
    • Aortic dissection
    • Acute traumatic aortic injury
    • Aortic coarctation
  • Thoracic Aneurysm Repair in Elderly Patients: Complications
    • Mortality rate is 7-12% in elective cases
    • Mortality is up to 40% in elective cases
  • CTA and Thoracic Stent Grafts
    • Pre-operative planning
    • Post-operative assessment
        - Endoleak Graft movement or fracture
        - Size of native aorta
  • "Potential complications of endovascular stent placement include endoleaks, stent migration, pseudoaneurysms, dissection, aortic perforation, kinking, thrombosis, and coverage of vital branch vessels."

    Thoracic Aortic Stent-Grafts: Utility of Multidetector CT for Pre- and Postprocedure Evaluation
    Bean MJ, Johnson PT, Roseborough GS, Black JH, Fishman EK
    RadioGraphics 2008; 28:1835-1851
  • Endovascular Stent Placement: Applications
    • Penetrating ulcers
    • Aortic dissection
    • Aortic aneurysms
    • Aortic rupture
    • Congenital abnormalities
  • Endovascular Stent Placement: Complications
    • Endoleaks
    • Stent migration
    • Pseudoaneurysms
    • Dissection
    • Aortic perforation
    • Kinking
    • Thrombosis
    • Coverage of vital branch vessels
  • "End diastolic diameter 95% confidence levels were 2.5-3.7 cm for the aortic root, 2.1-3.5 cm for the ascending aorta, and 1.7-2.6 cm for the descending thoracic aorta. Aortic diameters were significantly greater at end systole than end diastole (mean difference 1.9 ± 1.2 mmfor ascending aorta and 1.3 ± 1.8 for descending thoracic aorta. P < 0.001)"
  • "End diastolic diameter 95% confidence levels were 2.5-3.7 cm for the aortic root, 2.1-3.5 cm for the ascending aorta, and 1.7-2.6 cm for the descending thoracic aorta. Aortic diameters were significantly greater at end systole than end diastole (mean difference 1.9 ± 1.2 mmfor ascending aorta and 1.3 ± 1.8 for descending thoracic aorta. P < 0.001)"

    Assessment of the thoracic aorta by multidetector computed tomography: Age and sex specific reference values in adults without evident cardiovascular disease
    Lin FY et al.
    J Cardiovasc Comput Tomogr (2008) 2, 298-308
  • "Aortic diameters were significantly greater at end systole than end diastole (mean difference 1.9 ± 1.2 mmfor ascending aorta and 1.3 ± 1.8 for descending thoracic aorta. P < 0.001)."

    Assessment of the thoracic aorta by multidetector computed tomography: Age and sex specific reference values in adults without evident cardiovascular disease
    Lin FY et al.
    J Cardiovasc Comput Tomogr (2008) 2, 298-308
  • Patent Ductus Arteriosus (PDA): Facts

    - Isolated Patent Ductus Arteriosus accounts for up to 10-12% of all congenital heart anomalies
    - Most incidentally discovered PDAs in adult are asymptomatic
    - Diagnosis on CT is based on defining a vessel connecting the main pulmonary artery and the aorta that is patent
  • Patent Ductus Arteriosus (PDA): CT Findings

    - Calcification at the site of the PDA is common
    - Communication best seen on MPR and 3D images
    - Flow may be from aorta to pulmonary artery or pulmonary artery to aorta
  • Aortic Root Imaging: Facts

    - Diameter of aortic root is less than or equal to 3.9 cm
    - Diameter of ascending aorta is less than or equal to 3.5 cm at level of right pulmonary artery
    - Diameter of normal aortic arch is less than or equal to 3.0 cm
    - Diameter of normal descending aorta is less than or equal to 2.5 cm
  • Aortic Root Aneurysms: Associated Syndromes

    - Marfans syndrome
    - Loeys Dietz syndrome
    - Ehlers Danlos syndrome
    - Bicuspid aortic valve
    - Familial thoracic aortic aneurysm syndrome
  • "Loeys-Dietz Syndrome manifests with aggressive vascular pathology. Aneurysms may form at a young age and have a propensity for arterial dissection. In addition, aneurysms rupture at diameters smaller than those used to dictate surgical intervention for other syndromes and disorders".

    Loeys-Dietz Syndrome: MDCT Angiography Findings Johnson PT, Chen JK, Loeys BL, Dietz HC, Fishman EK AJR 2007;189; 226
  • Coarctation of the Aorta:Facts

    - Narrowing of aortic lumen results in LV hypertrophy
    - Collaterals and rib notching are common
    - May be isolated finding or associated with other cardiac issues
  • Coarctation of the Aorta:Facts

    Associated with cardiac anomalies

    - Bicuspid valve (50%)
    - VSD (33%)
    - PDA (66%)
    - Subaortic and mitral stenosis
  • Coarctation of the Aorta: Facts

    - 20-30% of Turners syndrome patients have a COA
    - Males > females by 2-1
  • "Endovascular stent graft repair is less invasive in patients with chronic and acute descending thoracic aortic aneurysm and dissection."

    Descending Thoracic Aortic Diseases: Stent-Graft Repair
    Fattori R et al. Radiology 2003; 229:176-183
  • Stent-Graft Placement in the Thoracic Aorta: Indications

    - Descending thoracic aneurysms
    - Dissection of descending aorta
    - Ulcers in descending aorta
    - Repair mycotic aneurysm
    - Post-traumatic aortic rupture
  • Thoracic Aorta: Pitfalls in CT Scanning

    - False positive dissection due to motion (cardiac and/or respiratory) or streak artifact of SVC
    - Aortic root
    - Ascending aorta
    - Aortic arch
  • CT of the Thoracic Aorta: Clinical Applications

    - Suspected aneurysm or dissection
    - Thoracic trauma
    - Vasculitis
    - Congenital disease (i.e. COA)
    - Pre-operative stent planning
    - Follow up of stent placement
  • CT of the Thoracic Aorta: Causes of Study Failures

    - Injection technique faulty (too slow,contrast extravasation, etc.)
    - Poor scan timing (data acquisition to contrast delivery)
    - Patient motion during study
  • CT of the Thoracic Aorta: Pitfalls

    - Artifacts off venous structures tend to be worse for left sided injections and create problems with the arch vessels as well as the ascending aorta
    - Possible solutions: saline chaser, caudal-cranial scanning
  • CT of the Thoracic Aorta: Pitfalls

    - Aortic pulsation is an issue in the aortic root and ascending aorta and can result in false positive studies
    - Possible solutions: faster scanners (4-16-64), cardiac gating, partial scan data reconstruction (half scan reconstruction)
  • MDCT vs. MR vs. TEE

    - Alternative diagnosis best defined on CT study
    - Pulmonary embolism
    - Mediastinal mass
    - Coronary artery occlusion
  • Intramural Hematoma: MDCT Findings

    - High CT attenuation on non contrast CT scans
    - Focal ulcer usually present
    - More common in descending aorta but occurs in ascending aorta as well
  • Congenital Anomalies of the Thoracic Aorta

    - Sequestration
    - Vascular rings
    - Coarctation of the aorta
    - Abberrant vessels
    - Right sided arch and associated anomalies
  • "The optimal reconstruction phase varied between patients, and this was directly related to the heart rate."

    Thoracic Aorta at Multidetector Row CT: Motion Artifact with Various Reconstruction Windows
    Morgan-Hughes GJ et al.
    Radiology 2003; 228:583-588
  • Aortic Stenosis: Etiology

    - Coarctation or pseudocoarctation
    - Midaortic dysplastic syndrome
    - Atherosclerosis
    - Takayasu arteritis
    - Aortic dissection
    - Retroperitoneal fibrosis
    - S/P surgical repair
  • True vs False Aneurysm

    - True Aneurysm-thinning and stretching of the vessel wall due to weakening of its structural integrity
    - False or pseudoaneurysm- extravascular hematoma that communicates with a vessel and is contained by a fibrous capsule
  • Pseudoaneurysms: Etiology

    - Trauma
    - Iatrogenic
    - Infection
© 1999-2018 Elliot K. Fishman, MD, FACR. All rights reserved.