Aortic Aneurysms & Rupture: NEET PG Radiology
1. Abdominal Aortic Aneurysm (AAA)
- Definition: Focal dilation of the abdominal aorta ≥ 3.0 cm.
- Imaging Gold Standard: CECT is the diagnostic study of choice for surgical planning.
- Screening: One-time ultrasound for men aged 65–75 who have ever smoked.
- Morphology: Most are fusiform; saccular aneurysms are often associated with infection (mycotic).
2. Signs of Impending Rupture on CT
| Sign | Description |
|---|---|
| Draped Curtain Sign | The aorta loses its sharp definition and drapes over the spine, highly suggestive of contained rupture. |
| Crescent Sign | High-density intramural hematoma within the thrombus signifies acute wall stress. |
| Focal Discontinuity | Break in the peripheral calcification of the aneurysm wall. |
3. Thoracic Aortic Dissection (Stanford Classification)
- Type A: Involves the ascending aorta (requires emergent surgical intervention).
- Type B: Involves only the descending aorta distal to the left subclavian artery (often managed medically unless complicated).
- Radiological Findings: “Intimal flap” separating the true and false lumen. The false lumen is often larger, has a “cobweb sign” (remnants of media), and shows slower filling of contrast.
4. Management Pearls
- AAA Repair Indications: Diameter ≥ 5.5 cm (men) or ≥ 5.0 cm (women), or rapid expansion (>0.5 cm in 6 months).
- Dissection Therapy: Immediate BP and heart rate control (beta-blockers like Esmolol or Labetalol) to reduce shear stress (𝑑𝑃/𝑑𝑡).