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.

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Patricia Tung HMS IIIGillian Lieberman, MD

January 2005

Many thanks to:Many thanks to:

Atif Zaheer, MDGillian Lieberman, MDPamela LepkowskiLarry Barabas, our Webmaster