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Aortic aneurysm imaging
 

Aortic aneurysm imaging

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  • The dilated / aneurysmatic thoracic aorta can be seen on both the frontal and lateral chest radiograph.The para-sagittal multi-planar reconstruction from the CT-angiography nicely shows the ascending aortic aneurysm with normal width of the rest of the thoracic aorta.
  • The dilated / aneurysmatic thoracic aorta can be seen on both the frontal and lateral chest radiograph.The para-sagittal multi-planar reconstruction from the CT-angiography nicely shows the ascending aortic aneurysm with normal width of the rest of the thoracic aorta.
  • Marfansyndrome and annuloaorticectasia in a 40-year-old man.Contrast-enhanced CT scan (a)and three-dimensional VR image (b)show a pear-shaped aorta that tapers to a normal aortic arch, a finding characteristic of Marfan syndrome and annuloaorticectasia.
  • The angiographic phase displays an extensive sacular dilatation of the descending aorta  with thick mural thrombus of semilunar shape. Wlight displacement of the left tracheobronchial tree. No evidence of rupture or aortic dissection. The spleen shows multiple puntiform calcifications. Liver. pancreas, kidneys and adrenal glands within normal limits
  • Contrast-enhanced CT scan obtained in a 50-year-old man shows a retroesophagealmediastinalabscess and a mycoticpseudoaneurysm of the descending thoracic aorta (arrow)
  • Reconstructed computed tomographic angiogram
  • Early arterial phase of a posteroanterior abdominalaortogram showing a bilobed aneurysm (arrows)originating just below the renal arteries
  • Axial enhanced CT image shows 7-cm abdominal aortic aneurysm with faint crescentic area of increased attenuation within mural thrombus (arrows). Patient was notsurgical candidate due to comorbid conditions.B, Enhanced CT image obtained 3 months after A shows anterior aneurysm rupture (black arrow) with associated retroperitoneal hemorrhage (white arrows).
  • Axial enhanced CT image shows 7-cm abdominal aortic aneurysm with faint crescentic area of increased attenuation within mural thrombus (arrows). Patient was notsurgical candidate due to comorbid conditions.B, Enhanced CT image obtained 3 months after A shows anterior aneurysm rupture (black arrow) with associated retroperitoneal hemorrhage (white arrows).
  • CT scan shows severe tortuousity and aneurysmal dilataion of abdominal aorta at the origin of renal arteries which extended to the bifurcation of aorta associated with extensive mural thrombosis and severe erosion and scalloping of anterior part of L3 and L4 vertebrae and loss of outline of the right psoas muscle.Contrast material completely filled renal and common iliac arteries.Threre are no evidence of mesenteric ischemia, free fluid in peritoneal cavity or contrast material in the surrounding hematoma.
  • neurysm rupture in a 65-year-old man. Nonenhanced CT scan shows a ruptured atherosclerotic aneurysm of the descending thoracic aorta. Note the high-attenuation fluid in the left pleural space, a finding that represents acute hemothorax.
  • axial CT angiograms obtained immediately after MRI reveal largeright retroperitoneal hematoma with contrast extravasation from posterolateralaorta (arrows, C and E). Operatively, large right retroperitoneal hematoma was seen,and pathologic evaluation revealed area of aortic wall discontinuity and associatedorganized hematoma.
  • Nonenhanced (a, b)and contrast-enhanced (c)CT scans show an aortoesophageal fistula and intraesophageal rupture of a saccular descending TAA. High-attenuation blood is seen within the mediastinum in aand within the esophagus in b.
  • CT angiographic images depict small gas bubbles within a ruptured aneurysm sac (arrows ina,b,andd), as well as disruption of the anterior aortic wall, with a faint fistulous tract between thethrombosed portion of the aortic aneurysm and the third portion of the duodenum (a
  • Axial CT angiograms show aortocaval fistula (arrow) and right retroperitonealhemorrhage.
  • Endoleak, defined as contrast enhancement outside the stent-graft

Aortic aneurysm imaging Aortic aneurysm imaging Presentation Transcript

  • AORTIC ANEURYSM & COMPLICATIONS Dr. P SANDEEP
  • Aortic root 1.  valve, annulus, and sinuses Ascending aorta 2.  Root to the origin of the right brachiocephalic A Aortic arch 3.    Right brachiocephalic A to the attachment of the ligamentum arteriosum Proximal (right brachiocephalic artery to lt subclavian A) Distal/Isthmus (lt subclavian A to attachment of the ligamentum arteriosum) Descending thoracic aorta 4.   ligamentum arteriosum to the aortic hiatus in the diaphragm Aortic spindle:most proximal portion of the descending thoracic aorta appears slightly dilated
  • Aneurysm True aneurysm Contain intima, media, and adventitia Fusiform Dilatation atherosclerosis False aneurysm pseudoaneurysm contained by the adventitia or periadventitial tissues. Saccular Penetrating trauma atherosclerotic ulcers or infection
  • Aortic Aneurysm Thoracic AA greater than 4 cm DA greater than 3 cm 1. 2. DA should never be larger than the AA at a given scan level The ratio of the coronal diameter of the AA to that of the DA should be about 1.5:l. Abdominal Focal dilatation of the abdominal aorta that is 50% greater than the proximal normal segment or that is greater than 3cm in maximum diameter. Less common More common Atherosclerosis (M.C) Atherosclerosis (M.C) Often identified incidentally on imaging of the chest. Presentation: Pain(m.c) Mostly asymptomatic unless they leak or rupture. Ruptured aneurysms present with severe abdominal or back pain and hypotension / shock. Ascending(Anterior) arch (neck pain) descending (mid-scapular) Due to compression or rupture Descending aorta (at the level of the ligamentum arteriosum, just distal to the origin of the subclavian artery.) Below the level of origin of renal arteries
  • Crawford classification of Thoracoabdominal aortic aneurysms  Type1:   Type II:   left subclavian A to aortic bifurcation Type III:   left subclavian A to renal A mid-descending aorta to aortic bifurcation Type IV:  upper abdominal aorta and all or none of the infrarenal
  • CAUSES     Atherosclerosis (most common) Chronic aortic dissection Vasculitis e.g. Takayasu arteritis Connective tissue disorders :       Marfan syndrome Ehlers-Danlos syndrome Mycotic aneurysm Traumatic pseudoaneurysm Anastomotic pseudoaneurysm Inflammatory abdominal aortic aneurysm Associations of AAA:  Common iliac artery (CIA) aneurysm  Popliteal artery aneurysm
  • Role of imaging 1. 2. 3. 4. Detection Monitoring of rate of growth Pre-operative planning Post-operative follow-up
  • Radiography: TAA: Initial identification of thoracic aortic aneurysms can be suspected from chest radiograph.  Most commonly, a mediastinal mass or enlarged segment of the aorta  Curvilinear mural calcification  Non-specific Displacement and compression of the esophagus or trachea and bronchi, may be visible.  Erosion of the thoracic vertebrae and posterior ribs.  Left pleural effusion suggests rupture 
  • Radiography: AAA:  may be visible as an area of curvilinear calcification in the para-vertebral region on either abdominal or lumbar spine films
  • ULTRASONOGRAPHY TAA:  No role of transthoracic ultrasound of no use.  Transoesophageal echocardiography can visualise much of the descending aorta, but due to its invasive nature is not routinely used.
  • ULTRASONOGRAPHY AAA:  Simple, safe and inexpensive.  Sensitivity ~ 95% and specificity ~ 100%.  Preferred choice for monitoring of small aneurysms  US may help determine the size of the aneurysm and help identify hemoperitoneum.  However, the utility of US for identifying an impending rupture or a contained rupture of an aneurysm is limited.
  • COMPUTED TOMOGRAPHY  Unenhanced CT:  may help detect an aneurysm rupture by depicting an AAA with surrounding retroperitoneal hemorrhage.  Calcification  Contrast-enhanced CT:  Size of the aneurysmal lumen  Presence of active extravasation  Calcification  Intraluminal thrombi  Displacement or erosion of adjacent structures
  • TAA: 1. Relationship of the aneurysm to the arch vessels 2. Descending aorta:  3. The esophagus is displaced to the right, and the trachea and bronchi are displaced anteriorly. Aortic arch and ascending aorta:  Produce compression rather than displacement of adjacent mediastinal structures
  •  AAA  Relationship of the aneurysm to the celiac a, SMA, renal a, and IMA.  Mural thrombus calcification may be confused for displaced intima in aortic dissection
  • CT angiography   Gold standard. CT angiography has become routine for imaging of a suspected rupture. (R/O appendicitis, pancreatitis, or bowel obstruction )  Accurately delineates  Size and shape of the AAA  Its relationship to branch arteries and aortic bifurcation.  In detecting and sizing common iliac artery aneurysms.
  • MRI and MR angiography:  Same as for CTA but can be more costly and less widely available.
  • Aortic aneurysm, Marfan syndrome. Parasagittal spin-echo magnetic resonance image demonstrates marked dilatation of the aortic root (A). A smaller aneurysm (arrows) of the proximal descending aorta also is seen.
  • AORTOGRAPHY  Conventional aortography now has a limited role in the preoperative evaluation of AAAs. Drawbacks:  underestimate the size of the aneurysm.  invasive nature,  cost  risk of exposure to large amounts of iodinated contrast.
  • Complications TAA 1. Rupture 2. Distal embolisation 3. Fistula formation 1. aorto-oesophageal fistula 2. aorto-bronchial fistula AAA 1. Rupture 2. Pseudoaneurysm from chronic contained leak / rupture 3. Distal thromboembolism & Thrombotic occlusion of branch vessel 4. Aorto-enteric fistula 5. Infection 6. Compression of adjacent structures if large (rare) 7. Vertebral erosion
  • Signs of Impending rupture Increase in size Thrombus and calcifications: 1. 2.   3. 4. 5. Decreased thrombus-to-lumen ratio A focal discontinuity in circumferential wall calcifications High-attenuation crescent sign - sign of impending rupture Draped aorta sign - sign of contained rupture Retroperitoneal hematoma
  • High attenuating crescent sign    Specific sign of impending AAA rupture / contained rupture. Represents an acute hematoma or bleed within either the mural thrombus or the aneurysmal wall, especially when detected on unenhanced CT-scans. The crescent need to be well defined and of higher attenuation than the psoas muscle on enhanced scans or of higher attenuation than that of the patent lumen on unenhanced scans.
  • Draped aorta sign  Refers to indistinctness of the posterior wall of the aorta from the adjacent structures .  The posterior aortic wall Is unidentifiable and follows the vertebral contour (draped over vertebral body).  Associated with chronic contained rupture of an abdominal aortic aneurysm with vertebral erosion1.  Highly indicative of aortic wall deficiency and a
  • AORTIC RUPTURE TAA:  Aortic aneurysms can rupture into the mediastinum, pleural cavity, pericardium, or adjacent luminal structures such as the airway or esophagus AAA:  Rupture most commonly involves the posterolateral aorta with hemorrhage into the retroperitoneum  Accumulates in perinephric space, other retroperitoneal compartments, duodenum, psoas muscle and peritoneal cavity
  • AORTIC RUPTURE In stable patient CT is first choice of imaging 1. 2. 3. Characterize AAA (site, size, extent and relations) Identify rupture Contrast: differtiates perianeurysmal fibrosis (Detectable enhancement) from hematoma (no enhancement) 4. In AAA to r/o obstruction appendicitis, pancreatitis, or bowel
  • False positives: 1. Periaortic fibrosis 2. Asymmetric thrombus 3. Volume averaging of periaortic tissues with lumen at the neck of aneurysm 4. Unopacified 3rd and 4th part of duodenum 5. Retroperitoneal lymphadenopathy
  • Aortobronchial fistula  Manifests clinically as hemoptysis  CT as consolidation in the adjacent lung due to hemorrhage  Most aortobronchial fistulas (90%) occur between the descending aorta and the left lung.   Communication with the esophagus (aortoesophageal fistula) is less com
  • Aortoesophageal fistula:  Hematemesis and dysphagia.  CT:  Mediastinal hematoma  Intimate relationship of the aneurysm to the esophagus,  Rarely, contrast material extravasation into the esophagus
  • Aortoenteric Fistulas:      Primary: atherosclerotic aortic aneurysms Secondary: aortic reconstructive surgery. M.C : duodenum (third and fourth portions). Symptoms: abdominal pain, hematemesis, and melena. CT imaging features:    Abdominal aortic aneurysm, often with signs of rupture Intraluminal and periaortic extraluminal gas. CECT: Contrast material extravasation from the aorta into the involved portion of the bowel, if a patent
  • MANAGEMENT 1. 2. open repair endovascular repair TAA AAA ascending aneurysm > 5.5 Aneurysm > 3cm cm descending aneurysm > 6.5 cm Growth rate > 1 cm/year Growth rate > 1 cm/year Symptomatic patients repaired regardless of size Symptomatic patients repaired regardless of size
  • CT in Post-op period for complications open repair: 1.    Endovascular repair: 2.       Graft dehiscence Pseudoaneurysm formation Infection Endoleaks Migration Collapse Pseudoaneurysm or Dissection The native aorta may be left in situ and appears as an irregular curvilinear area of dense calcification or a rind of soft tissue, often with fluid between it and the graft. It should not be mistaken for dissection flap.