Imaging Sciences Interesting Cases
Case 69
Richard Gong, MD
Clinical Presentation: A 65-year-old male presented to the emergency department after cardiac arrest and resuscitation.
Imaging Findings: Non-contrast and contrast enhanced images through the thoracic aorta demonstrate an intimomedial flap extending from the ascending aorta into the aortic arch. There is contrast within the true and false lumen. There is no involvement of the aortic root.
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| Figure 1. Non-contrast image of the ascending aorta. | Figure 2. Contrast-enhanced image through the ascending aorta demonstrates an intimomedial flap with contrast in the true and false lumina. |
| Figure 3. The intimomedial flap extends to, but not beyond the aortic arch. |  |
Diagnosis: Type A Aortic Dissection
Discussion: Transmission computerized tomography (TCT) has become the examination of choice for the initial evaluation of any patient suspected to have an aortic dissection. Other imaging options for detecting aortic dissection include echocardiography, especially transesophageal, MRI, and aortography. The hallmark for aortic dissection on CT is an intimomedial flap with contrast in the true and false lumina.
There are three classification systems for describing aortic dissection. The first was described by DeBakey, et al. in 1964 based on the anatomic location of the abnormality.
- Type I aortic dissection involves the ascending and descending aorta.
- Type II involves the ascending aorta and extends to the origin of the brachiochephalic artery.
- Type III involves the descending aorta beginning at the origin of the left subclavian artery.
In 1970 the Stanford-Daily classification system was developed and is currently the more commonly used system.
- Type A involves the ascending aorta, and
- Type B is confined to the descending aorta beginning at the origin of the left subclavian artery.
This system is in favor in part because it serves as a basis for management. Most commonly Type A aortic dissections are treated surgically and type B aortic dissection are treated medically.
In 1999 Sevensson proposed a variant system in an attempt to describe the pathologic origin of acute aortic injury at presentation.
- Class 1 includes the classic aortic dissection with separation of the intima from the medial and the creation of an intimomedial flap and dual lumina.
- Class 2 includes aortic intramural hematoma, with separation of the intima from the medial, without an intraluminal tear or flap.
- Class 3 includes subtle aortic intimal tears with an eccentric bulge and without hematoma.
- Class 4 includes atherosclerotic penetrating aortic ulcers.
- Class 5 includes iatrogenic or traumatic aortic dissections.
References:
- Petasnick JP. Radiologic evaluation of aortic dissection. Radiology. 1991 Aug;180(2):297-305. [PubMed]
- Hayter RG, Rhea JT, Small A, Tafazoli FS, Novelline RA. Suspected aortic dissection and other aortic disorders: multi-detector row CT in 373 cases in the emergency setting. Radiology. 2006 Mar;238(3):841-52. [PubMed]