Imaging Sciences Interesting Cases
Case 173
Sara Ann Majewski, MD
Clinical Presentation: Patient is a 74-year-old male presenting for follow-up of known type B aortic dissection.
Imaging Findings: This is a typical Stanford type B aortic dissection beginning beyond the take-off of the left subclavian artery, comprised of a patent true and false lumen, extending into the abdomen.
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| Figure 1: CT scout image demonstrates widened mediastinum. |
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| Figure 2: Contrast enhanced CT demonstrates dissection flap within the aorta, just beyond the origin of the left subclavian artery. (Move mouse over image to view labels.) |
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| Figure 3: Contrast enhanced CT demonstrates dissection flap in the aorta with subtle extension into the left renal artery. |
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| Figure 4: Contrast enhanced CT demonstrates dissection flap extending into the left common iliac artery. (Move mouse over image to view labels.) |
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| Figure 5: MRI axial gradient echo sequence with contrast demonstrates dissection flap within the aorta, just beyond the origin of the left subclavian artery. (Move mouse over image to view labels.) |
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| Figure 6: MRI axial gradient echo sequence with contrast demonstrates the superior mesenteric artery originating from the true lumen of the aorta. (Move mouse over image to view labels.) |
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| Figure 7: MRI axial gradient echo sequence with contrast demonstrates dissection flap with subtle extension into the left renal artery. (Move mouse over image to view labels.) |
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| Figure 8: MRI axial gradient echo sequence with contrast demonstrates dissection flap extending into the left common iliac artery. (Move mouse over image to view labels.) |
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| Figure 9: MRI sagittal gradient echo maximal intensity projection (MIP) with contrast demonstrating Stanford type B aortic dissection |
Diagnosis: Aortic dissection, type B
Discussion: Please refer to interesting case 69 for aortic dissection classification schema.
Aortic dissection has a mortality rate of 5%–45% in type A and 6%–39% in type B [3]. If the dissection extends into branch arteries, like the superior mesenteric artery, mortality may reach 85% [1].
To determine the prognosis of type B aortic dissection, Tsai and colleagues searched the International Registry of Acute Aortic Dissection for patients surviving initial hospitalization. Almost 25% of patients died within 3 years [4]. With partial thrombosis of the false lumen, the risk of mortality is 2.7 times that of patients with a completely patent false lumen [4].
Since there is a high mortality rate associated with surgical repair of aortic dissection involving the aortic arch, medical therapy is advocated. Up to half of patients with chronic type B dissections develop aneurysms one to five years after onset. Chronic type B dissection often causes the false lumen to enlarge and the true lumen to become smaller [3].
Ischemic events can necessitate intervention.
Czermak and colleagues concluded that type B aortic dissections within and as much as 2 cm distal to the origin of the left subclavian artery can be treated with endovascular stent-graft placement [2]. Further study of endovascular intervention for type B aortic dissections has been advocated by multiple authors.
References:
- Cambria RP, Brewster DC, Gertler J, et al. Vascular complications associated with spontaneous aortic dissection. JJ Vasc Surg. 1988 Feb;7(2):199-209. [PubMed]
- Czermak B, Waldenberger P, Fraedrich G, et al. Treatment of Stanford type B aortic dissection with stent-grafts: preliminary results. Radiology. 2000 Nov;217(2):544-50. [PubMed]
- Kato M, Matsuda T, Kaneko M, et al. Outcomes of stent-graft treatment of false lumen in aortic dissection. Circulation. 1998 Nov 10;98(19 Suppl):II305-11; discussion II311-2. [PubMed]
- Tsai T, Evangelista A, Nienaber C, et al. Partial thrombosis of the false lumen in patients with acute type B aortic dissection. N Engl J Med. 2007 Jul 26;357(4):349-59. [PubMed]