Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
Radiologic Diagnosis of Radiologic Diagnosis of Thoracic Aortic AneurysmsThoracic Aortic Aneurysms
Patricia Tung, Harvard Medical School Year III
Gillian Lieberman, MD
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
BackgroundBackground
Incidence 6 cases per 100,000 patient years– Less common than AAA– Incidence increasing over last 30 years
Typically 6th-7th decadeMales 2-4 x > than femalesFamilial predispositionExpand less rapidly than AAA
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
Risk FactorsRisk FactorsAtherosclerosisCT disordersInfection: salmonella, staph aureus, syphilisBicuspid Ao valve and coarctation => post-stenotic dilatationTrauma: deceleration injuriesTakayasu’s and Giant Cell arteritides
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
PathophysiologyPathophysiologyAtherosclerosis– Proteolytic factors in inflammatory plaques destroy
elastin and collagen, weakening vessel wallCystic medial degeneration – Elastic tissue fragmentation– Separation of elastic and muscular elements of media
by amorphous ECM– Provides substrate for HTN and other insults
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
Categorization of TAA: by Categorization of TAA: by locationlocation
Ascending: Ao valve to innominate arteryArch: involving any of the branch vesselsDescending: distal to the left subclavianartery
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
Complications of TAAComplications of TAARupture – universally fatal except in rare cases of containmentEmbolization – stroke, infarctDissection – stroke, infarct, renal failure, paralysisSepsis – undetected mycotic aneurysms and pseudoaneurysms
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
Aneurysm vs. Aneurysm vs. PseudoaneurysmPseudoaneurysm vs. Dissectionvs. Dissection
Aneurysm = 3 layers; >1.5x nl diameter; blood within vascular systemPseudoaneurysm < 3 layers; contains adventitia +/- mediaDissection of media via intimal flap=>blood filled channel in middle-outer 1/3 of laminar planes
www.medstudents.com images in cardiology
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
TreatmentTreatment
Size = 1° determinant of rupture; uncommon <5cm or expansion <1cm/yearSurgery if >5.5 cm or sxUntx TAA>6cm => risk rupture or dissection 6.9%, death 11.8%/year (Davies et al).
Perko et al. Unoperated Aortic Aneurysms: A Survey of 170 Patients. Ann Thorac Surg 1995; 59; 1204-9.
Survival for Untx TAA, T/AAA, AAA
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
Clinical PresentationClinical PresentationAsx in absence of expansion or bleedingSx related to mass effect or circulatory compromiseUp to 13% patients have multiple aortic aneurysms
=>Most commonly detected as incidental finding on plain film
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
CXR: Radiologic FindingsCXR: Radiologic Findings
Not used for diagnosisAortic silhouette abnormal 80-90% cases– Diffuse widening mediastinum– Mediastinal mass– Pleural effusion– Displacement of NG tube to the right– change in aortic contour over time**
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
CXR: Radiologic FindingsCXR: Radiologic FindingsAneurysm seen as mediastinal mass adjacent to aortaCan be indistinguishablefrom 1° lung cancer
www.aic.cuhk.edu.hk/web8/thoracic_aortic_aneurysm.htm
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
CXR: Radiologic FindingsCXR: Radiologic Findings
Diffuse dilatation of descending aortaand arch
Can be difficult to distinguish from tortuous or ectatic aorta
www.aic.cuhk.edu.hk/web8/thoracic_aortic_aneurysm.htm
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
CXR: TAA RuptureCXR: TAA RuptureWidened mediastinumRight hemothoraxChange in aortic contour compared to previous CXR
www. Health.all-refer.com
=>With high clinical suspicion, more sophisticated study needed to confirm dx and size determination
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
Primary Diagnostic ModalitiesPrimary Diagnostic Modalities
AortogramCT/CTAMRI/MRATEE
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
AortogramAortogramGold standard until 1990sReplaced by helical CT and MRI/MRAReserved for resolution of v. small vessels or pts unable to breathholdNo evidence of dissection. Ectatic
descending aorta with a penetrating ulcer on the lateral wall.
Harris and Rosenbloom. Images in Clinical Medicine. NEJM 1997; 336 (26): 1875, Figure 1.
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
CT: Descending Aortic AneurysmCT: Descending Aortic AneurysmBest for emergent settingsWidely available, less expensive than MRIDelineates morphology, pattern, distribution of thrombus and calcification
Harris and Rosenbloom. Images in Clinical Medicine. NEJM 1997; 336 (26): 1875, Figure 1.
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
CT: Additional BenefitsCT: Additional BenefitsHyperdensityidentifies acute injury Visualization of dissection and intimal flap
PACS, BIDMC
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
MRIMRIShows lumen and vessel wall; best assessment of true size Excellent vessel anatomy and surrounding structuresLeast renal toxicityTime consuming; not for unstable patients
www.medstudents.com images in cardiology
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
MRAMRA3D Gado MRA shows blood flowCINE imaging gives functional assessment of Ao valve; can show intimal flapDoes not visualize adventitia well
=>Differences in treatment make visualization of entire aorta critical.
home.earthlink.net/~radiologist/tf/060302.htm
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
MRI Coronal View: MRI Coronal View: Ascending Aortic AneurysmAscending Aortic Aneurysm
PACS, BIDMC
Signal loss in ascending aorta c/w stenosis
Aneurysmal dilatation 4.6 x 4.1 cm at main PA
Smooth dilatation
No lumenal irregularity
No coarctation
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
MRI MRI SagittalSagittal View: View: ThoracoabdominalThoracoabdominal AneurysmAneurysm
PACS, BIDMC
TAA arising from arch to suprarenal aorta
No evidence of dissection currently
Eccentric mural thrombus vs. thrombosis of prior false lumen along anterior wall
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
MRI: MRI: ThoracoabdominalThoracoabdominal AneurysmsAneurysms
PACS, BIDMC
Tortuous descending aorta
Infrarenal aneurysm
Multiple bilateral renal cysts
1.5 cm cyst left lobe liver
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
Assessment with TEEAssessment with TEENot used for dx but provides functional informationGood for unstable patientsBlind spots vs. CT and MRI; Operator dependent
www.medstudents.com images in cardiology
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
TEE: Radiologic FindingsTEE: Radiologic Findings
Harris and Rosenbloom. Images in Clinical Medicine. NEJM 1997; 336 (26): 1875, Figure 1.
Severe atherosclerosisMildly enlarged descending aortaEccentric thickening of one wall Echogenicity consistent with thrombus or IMH
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
Patient J.D.Patient J.D.
77 year old male with chest discomfort, pressure between scapulae and hoarsenessPMH: COPD, prior asbestos exposure, PVD, HTNPSH: s/p aortobifemoral bypass graftElevated creatinine
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
ContrastContrast--enhanced CT at enhanced CT at PresentationPresentation
Disruption of inferior wall of aortic arch c/wpseudoaneurysm or contained ruptureAdjacent mediastinalhematomaPleural plaques c/wasbestos exposure
PACS, BIDMC
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
ContrastContrast--enhanced CT at enhanced CT at PresentationPresentation
Disruption of inferior wall of aortic arch c/wpseudoaneurysm or contained ruptureAdjacent mediastinalhematoma
PACS, BIDMC
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
ContrastContrast--enhanced CT 3 Days enhanced CT 3 Days LaterLater
PACS, BIDMC
Increased size of mediastinal hematoma adjacent to pseudoaneurysmIncreased pleural effusion, possible subacute hemothorax
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
Take Home PointsTake Home PointsHelical CT gives rapid assessment of major pathology; good for:– Acutely symptomatic– Question of additional thoracoabdominal pathology
MRI gives excellent detail; good for: – Asymptomatic and hemodynamically stable– Surgical planning– Patient contraindications
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
Take Home Points (cont’d)Take Home Points (cont’d)
TEE good for functional assessmentNon-angiographic modalities best for assessing non-lumenal anatomy
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Patricia Tung HMS IIIGillian Lieberman, MD
January 2005
ReferencesReferencesRubin GD. CT Angiography of the Thoracic Aorta. Seminars in Roentgenology 2003 April; 38(2): 115-133.Miller, WT. Thoracic Aortic Aneurysms: Plain Film Findings. Seminars in Roentgenology 2001 Oct; 36(4): 288-294.Roberts, DA. Magnetic Resonance Imaging of Thoracic Aortic Aneurysm and Dissection. Seminars in Roentgenology 2001 Oct; 36(4): 295-308.Nguyen, BT. Computed Tomography Diagnosis of Thoracic Aortic Aneurysms. Seminars in Roentgenology 2001 Oct; 36(4): 309-324.Scott CH, Keane MG, Ferrari VA. Echocardiography Evaluation of the Thoracic Aorta. Seminars in Roentgenology 2001 Oct; 36(4): 325-333.Soulen MC. Catheter Angiography of Thoracic Aortic Aneurysms. Seminars in Roentgenology 2001 Oct; 36(4): 325-339.Marx, Hockberger, Walls. Rosen’s Emergency Medicine, 5th edition. Vol (1); 406.Davies RR et al. Yearly Rupture or Dissection Rates for TAA: Simple Prediction Based on Size. Ann Thorac Surg 2002 Jan; 73(1): 17-27.