Daily Radiology Case

Explanation

Contrast-enhanced CT shows an intimal flap separating the true and false lumens within the descending thoracic aorta, with sparing of the ascending aorta consistent with a Stanford Type B aortic dissection. The pathophysiology involves an intimomedial tear allowing pulsatile blood to dissect within the medial layer, creating a false lumen propagated by chronic hypertensive shear stress. CT angiography is nearly 100% sensitive and specific and remains the gold standard, with key findings including the intimomedial flap, differential lumen opacification, intimal calcification displacement, and beak sign. Recognition is critical because Type A dissections require emergent surgical graft repair, whereas uncomplicated Type B cases are managed medically. Making accurate classification on imaging directly determinative of management.

Source: Shrestha A, Aortic dissection - Stanford type B. Case study, Radiopaedia.org (Accessed on 29 Apr 2026) https://doi.org/10.53347/rID-234309

Hints

• A 55-year-old man presents with progressive shortness of breath and bilateral lower extremity pitting edema that has worsened over several weeks. Notably, he denies any tearing chest pain, back pain, or syncopal episodes at the time of presentation.
• His past medical history is significant for long-standing, poorly controlled hypertension, and he admits to inconsistent adherence with his antihypertensive regimen. On examination, blood pressure is markedly elevated with a measurable differential between the upper extremities.
• Initial workup shows preserved renal function and unremarkable cardiac biomarkers, but the markedly elevated blood pressure and pulse asymmetry prompt urgent cross-sectional imaging of the chest and abdomen.
• Contrast-enhanced CT demonstrates ectasia of the descending thoracic aorta measuring up to 45 mm, with a thin linear filling defect coursing through the lumen and extending caudally to the infrarenal abdominal aorta. Two distinct contrast-opacified channels are clearly delineated, with no evidence of contrast extravasation into the mediastinum, pleural, or pericardial spaces.
• The larger of the two channels measures 21 mm and the smaller 11 mm, with no significant thrombus identified within either compartment, and the ascending aorta and aortic arch are entirely spared from the process.
• This entity carries an incidence of 5–30 cases per million annually with mortality approaching 50% within 48 hours if untreated; uncomplicated cases involving only this segment of the aorta are managed medically with strict blood pressure control, while endovascular intervention is reserved for complications such as malperfusion or impending rupture.