CT Scan for Penetrating Ulcer of Descending Aorta
For follow-up imaging of a penetrating aortic ulcer in the descending thoracic aorta, perform CT angiography (CTA) with both non-contrast and contrast-enhanced phases covering the entire aorta from thoracic inlet to pelvis.
Recommended Imaging Protocol
The optimal imaging sequence consists of 1, 2:
- Non-contrast CT first - Essential to detect intramural hematoma (IMH), which appears as high-attenuation within the aortic wall
- Followed by contrast-enhanced CTA - To delineate the ulcer crater, assess depth of penetration, identify associated complications, and evaluate branch vessel involvement
- Coverage from thoracic inlet to pelvis - Including iliac and femoral arteries to assess extent and plan potential endovascular treatment
Technical Specifications
Multidetector CT (≥16 detectors preferred) with 1, 3:
- Thin-section acquisition (≤3mm slice thickness)
- 50% reconstruction overlap
- Multiplanar reformations (MPR) and 3D reconstructions
- Arterial phase timing for optimal contrast opacification
ECG-gating is NOT mandatory for descending aortic pathology, as cardiac motion artifacts primarily affect the ascending aorta and root 1.
Why This Protocol
CT has excellent diagnostic accuracy for penetrating atherosclerotic ulcers (PAU) with sensitivities approaching 100% and specificities of 98-99% 1, 3. The 2014 ESC Guidelines rate CT as "excellent" (+++/+++) for diagnosing penetrating aortic ulcers, superior to echocardiography 3.
Key imaging findings to assess 1, 3, 4:
- Focal ulcer crater penetrating through calcified intima into media
- Displaced intimal calcifications (highly specific for PAU)
- Associated intramural hematoma (focal high-attenuation wall thickening)
- Aortic diameter and ulcer dimensions (depth >10mm, diameter >20mm indicate higher risk)
- Periaortic hematoma, pleural effusion, or mediastinal fluid (signs of impending rupture)
- Extent of atherosclerotic disease
Critical Surveillance Parameters
Follow-up imaging should specifically evaluate 3, 5, 6:
- Ulcer progression - Increasing depth or diameter
- Aortic expansion - Diameter >42-50mm warrants intervention consideration
- New complications - Development of pseudoaneurysm, IMH, or periaortic fluid
- Symptoms correlation - Pain recurrence indicates instability
Common Pitfalls to Avoid
- Don't skip the non-contrast phase - You'll miss subtle IMH that appears isodense to contrast-enhanced lumen 1
- Don't confuse PAU with other entities - Ulcerated plaques without medial penetration or intimal disruptions in IMH have different prognosis 6
- Don't limit imaging to chest only - PAUs can extend or coexist with abdominal pathology; complete aortic imaging is essential 1, 2
- MRI is inferior for PAU - Cannot reliably detect displaced intimal calcifications, which are pathognomonic for PAU 3
Alternative Modalities (Not Recommended for Routine Follow-up)
- Echocardiography (TTE/TEE): Poor sensitivity for descending aortic PAU; rated only "moderate" (++) by ESC guidelines 3
- MRI: Cannot visualize calcification displacement; less available emergently 3
- Conventional angiography: Invasive, cannot assess aortic wall or periaortic structures 7
The non-contrast plus contrast-enhanced CTA protocol provides comprehensive assessment of ulcer morphology, associated complications, and treatment planning in a single rapid acquisition 1, 3, 1.