Diagnostic Imaging Pathways - Aortic Dissection (Spontaneous)
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Population Covered By The Guidance
This pathway provides guidance for imaging adult patients with suspected non-traumatic aortic dissection.
Date reviewed: January 2012
Date of next review: January 2015
Published: January 2012
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The relative radiation level (RRL) of each imaging investigation is displayed in the pop up box.
| SYMBOL | RRL | EFFECTIVE DOSE RANGE |
 | None | 0 |
 | Minimal | < 1 millisieverts |
 | Low | 1-5 mSv |
 | Medium | 5-10 mSv |
 | High | >10 mSv |
Images
Image GalleryNote: These images open in a new page | ||
|---|---|---|
| 1 |  |
Aortic Dissection - Type A Image 1 (CT Angiography): Stanford type A Aortic Dissection involving the ascending and descending thoracic aorta (arrows). |
Teaching Points
Teaching Points
- Stanford classification of aortic dissection
- Type A dissection includes the ascending aorta
- Type B dissection does not involve the ascending aorta (i.e. distal to left subclavian artery)
- A chest radiograph is useful in excluding other causes of chest pain. A normal chest radiograph does not exclude the diagnosis of aortic dissection
- Contrast enhanced spiral CT scan is the initial investigation of choice for the evaluation of suspected spontaneous aortic dissection
ct
Computed Tomography (CT)
- Contrast enhanced spiral CT scan is the initial investigation of choice for the evaluation of suspected spontaneous aortic dissection 1
- Comparable accuracy to that of MRI and transoesophageal echocardiography (TOE) with sensitivity and specificity approaching 100% 2,3,4
- Superior to TOE and MRI in the assessment of aortic arch vessel involvement 2
- The diagnosis is based on the demonstration of an intimal flap, which separates the true from the false channel. Secondary findings include internal displacement of intimal calcifications, delayed enhancement of the false lumen and aortic widening 1,5
- Atypical forms of aortic dissection can also be recognised eg. intramural haematoma, penetrating atherosclerotic ulcer and atypical configurations of the intimal flap 1,6
- CT findings of: type A intramural haematoma, maximum thickness of haematoma, compression of true lumen, and pericardial or pleural effusion, can predict the progression of aortic intramural haematoma to aortic dissection 7
- Advantages 1,3
- Non-invasive, rapid test
- Widely available
- Allows distinction of type A from type B aortic dissection
- Allows imaging of the entire aorta and demonstrates the extent of involvement and organ ischaemia
- Permits follow-up of aortic dissection, aneurysm or intramural haematoma
- Limitations 1,3,4
- Does not provide information regarding the coronary arteries or aortic valve, although multislice CT shows promise in this area and further studies are required
- Disadvantages
- Exposure to ionising radiation
- Use of iodinated contrast materia.
cxr
Chest Radiography
- Radiographic abnormalities that may suggest aortic dissection include
- Widened mediastinum
- Widening of the aortic contour
- Difference in the diameter between the ascending and descending aorta
- Blurring of the aortic margin secondary to local extravasation of blood
- Unilateral / bilateral pleural effusion
- Separation of intimal calcification
- A literature review reported the accuracy of various radiological abnormalities in the detection of spontaneous aortic dissection
- Abnormal aortic contour - sensitivity 61% (95% CI 56-85)
- Pleural effusion - sensitivity 16% (95% CI 12-21)
- Displaced intimal calcification - sensitivity 9% (95% CI 6-13)
- Widened mediastinum - sensitivity 64% (95% CI 44-80)
- Abnormal chest radiograph - sensitivity 90% (95% CI 87-92)
- A chest radiograph is useful in excluding other causes of chest pain. A normal chest radiograph does not exclude the diagnosis of aortic dissection
mri
Magnetic Resonance Imaging (MRI)
- Comparable accuracy to that of CT and transoesophageal echocardiography 2,4
- Advantages 2,4
- Provides excellent visualisation of tear localisation, aortic regurgitation, side branch involvement and complications
- No exposure to ionising radiation
- Non-invasive
- Limitations 2,4
- Expensive
- Limited availability
- Long examination time
- Difficulty of monitoring haemodynamically unstable patients (limited access to the patient)
- Contraindicated in patients with pacemakers/certain heart valve prostheses
toe
Transoesophageal Echocardiography (TOE)
- Comparable accuracy to that of CT for detection of aortic dissection 2,4,8
- Advantages 2,4,8
- Can be performed at the bedside of critically ill patients
- Allows functional cardiac assessment
- Permits detection of coronary artery involvement
- Limitations 2,4,8
- Invasive
- Limited availability and/or expertise
- Obscuration of the proximal aortic arch by interference from air within the trachea
- Lack of visualisation of the abdominal aorta (the distal extent of the dissection may not be seen if it involves the abdominal aorta)
aort_d
Aortic Dissection
- Predisposing factors for spontaneous aortic dissection include
- Systemic hypertension
- Bicuspid aortic valve
- Coarctation of the aorta
- Marfan's syndrome
- Ehlers-Danlos syndrome
- Turner syndrome
- Giant cell arteritis
- Third trimester pregnancy
- Cocaine abuse
- Stanford classification of aortic dissection 1
- Type A dissection includes the ascending aorta
- Type B dissection does not involve the ascending aorta (i.e. distal to left subclavian artery)
- Type A dissections are usually surgical emergencies owing to the high risk of acute aortic regurgitation, occlusion of coronary arteries and pericardial rupture 1
References
References
References are graded from Level I to V according to the Oxford Centre for Evidence-Based Medicine, Levels of Evidence. Download the document
- Coulam CH, Rubin GD. Acute aortic abnormalities. Semin Roentgenol. 2001;36(2):148-64. (Review article)
- Sommer T, Fehske W, Holzknecht N, et al. Aortic dissection: a comparative study of diagnosis with spiral CT, multiplanar transoesophageal echocardiography, and MR imaging. Radiology. 1996;199:347-52. (Level II/III evidence)
- Oliver TB, Murchison JT, Reid JH. Spiral CT in acute non-cardiac chest pain. Clin Radiol. 1999;54:38-45. (Level III evidence)
- Nienaber CA, von Kodolitsch Y, Nicolas V, et al. The diagnosis of thoracic aortic dissection by noninvasive imaging procedures. N Engl J Med. 1993;328(1):1-9. (Level II evidence). View the reference
- Erbel R, Alfonso F, Boileau C, Dirsch O, Eber B, Haverich A, et al. Diagnosis and management of aortic dissection. Recommendations of the task force on aortic dissection, European Society of Cardiology. Eur Heart J. 2001;22:1642-81. (Practice guidelines)
- Williams MP, Farrow R. Atypical patterns in the CT diagnosis of aortic dissection. Clin Radiol. 1994;49:686-9. (Level IV evidence)
- Choi SH, Choi SJ, Kim JH, et al. Useful CT findings for predicting the progression of aortic intramural hematoma to overt aortic dissection. J Comput Assist Tomogr. 2001;25(2):295-9. (Level III evidence)
- Keren A, Kim CB, Hu BS, et al. Accuracy of biplane and multiplane transoesophageal echocardiography in diagnosis of typical acute aortic dissection and intramural hematoma. J Am Coll Cardiol. 1996;28:627-36. (Level II evidence). View the reference
- Klompas M. Does the patient have an acute thoracic aortic dissection? JAMA. 2002;287:2262-72. (Level III evidence)
Further Reading
- Sebastia C, Pallisa E, Quiroga S, et al. Aortic dissection: diagnosis and follow-up with helical CT. Radiographics. 1999;19:45-60. (Review article)
- Ciagarroa JE, Isselbacher EM, DeSanctis RW, et al. Diagnostic imaging in the evaluation of suspected aortic dissection. N Engl J Med. 1993;328:35-43. (Review article)
Information for Consumers
Information for Consumers
Information from this website |
Information from the Royal Australian and New Zealand College of Radiologists’ website |
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Consent to Procedure or Treatment Radiation Risks of X-rays and Scans Magnetic Resonance Imaging (MRI) |
Contrast Medium (Gadolinium versus Iodine) Iodine-Containing Contrast Medium Magnetic Resonance Imaging (MRI) Radiation Risk of Medical Imaging During Pregnancy Radiation Risk of Medical Imaging for Adults and Children |
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