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Aortic Dissection

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Aortic Dissection CT Aortogram
Aortic Dissection CT Aortogram


Identify the type of aortic dissection

  1. Stanford Type A
  2. Stanford Type B
  3. Stanford Type C

True v/s False Lumen of Aortic Dissection

  • Intimal defect – blood enters media of aortic wall – “dissects” the aortic wall longitudinally.
  • Two lumens separated by dissection flap: True lumen and False lumen – formed because of the dissection flap.
True LumenFalse Lumen
SizeUsually smaller (compressed by false lumen)Usually larger due to higher pressure and lesser resistance
Contrast densitySimilar to other arteriesLess dense contrast due to delayed opacification.
Thrombosis Less likelyCommon
ConfigurationNo beak or cobweb signBeak Sign. Cobweb sign
Distinguishing True lumen vs false lumen Aortic Dissection

Beak sign of false lumen: Acute angle commonly formed by the false lumen against the true lumen.

Bird Beak Sign (slide to compare)
CT Angiogram

Cobweb sign of false lumen: Fine strands of dissected media tissue forming a web cluster.
Mercedes Benz Sign : Triple channel dissection due to secondary dissection within one channel

  • Widening of superior mediastinum > 8cm and progressive aortic enlargement on radiographs.
  • CT is imaging modality of choice in acute cases. MRA is good for follow up.

Key is to report what portion of the aorta is involved.

Ascending aorta : Stanford AAcute worrisome – Acute management (Surgical).
Beyond ascending aorta – Stanford BBe calm (Conservative management).

Classification systems for Aortic Dissection

Stanford classification
Type A (60%): Involves ascending aorta, regardless of site of origin
Type B (40%): Does not involve ascending aorta
DeBakey classification
Type I: Originates in ascending aorta, involves at least aortic arch, and may involve descending aorta
Type II: Originates in and confined to ascending aorta
Type III: Originates in descending aorta; IIIa: Limited to descending aorta; IIIb: Extends below diaphragm

Stanford and DeBakey Classification of Aortic Dissection

Analysis and reporting algorithm for diagnostic CT findings

Remember the mnemonic : DISSECTION

Dissection or other acute aortic syndrome: Yes/No?
Is ascending aorta involved: Yes/No?
Intimal tear location
Size of the true and false lumen.
Segment(s) of aorta involved
Extent and involvement of aortic branches.
Complications –
Thrombus in the false lumen
Inspect False/True lumen
Other factors to consider : Trauma, age sex
Notify the provider

Source: Aortic Dissection and Other Acute Aortic Syndromes: Diagnostic Imaging Findings from Acute to Chronic Longitudinal Progression


  • Type A: Surgery due to involvement of aortic root
  • Type B: Conservative treatment and Surgery in complicated cases (organ ischemia, rupture, descending aorta > 6cm,hemodynamic instability.)
  • Mesenteric, renal, extremity ischemia
  • Rupture, aneurysmal enlargement of false lumen; descending aorta > 6 cm
  • Hemodynamic instability; pseudocoarctation syndrome; distal embolization.

Access the above case as a full DICOM image set (includes report impression): Aortic Dissection full DICOM set

References and further reading:

2 thoughts on “Aortic Dissection”

  1. Terrance A. Reppert

    It’s good to see writing that is so good that you know the writer has done the homework on the subject. I am impressed with your insight and viewpoints on this topic.

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