Should I get a CTA (Computed Tomography Angiography) of the chest, abdomen, or both?

CTA Chest and Abdomen/Pelvis for Aortic Pathology Evaluation

For suspected aortic pathology, a CTA of both chest and abdomen/pelvis with IV contrast is strongly recommended as the optimal imaging choice, as thoracic aortic pathology frequently extends below the diaphragm (98.6% of complicated type B aortic dissections extend into the abdomen). 1

Rationale for Combined Chest and Abdominal/Pelvic CTA

• CTA provides superior spatial and temporal resolution with homogeneous intraluminal contrast enhancement, allowing for comprehensive evaluation of the entire aorta 1
• Studies show that 98.6% of patients with complicated thoracic aortic dissections have dissections that extend below the diaphragm, highlighting the need for complete imaging 1
• Combined chest-abdomen-pelvis imaging allows assessment of:
  • Intimal flap extension into visceral arteries 1
  • Iliofemoral artery diameters and calcification (important for potential interventional planning) 1
  • Branch vessel involvement 1

Technical Considerations

• ECG gating is particularly valuable for imaging the ascending aorta to minimize cardiac motion artifacts and ensure measurements are made in the same phase of the cardiac cycle 1
• Studies show 5-10% difference in proximal descending thoracic aortic measurements between systole and diastole, emphasizing the importance of consistent acquisition timing 1
• CTA protocols typically include:
  • Arterial phase imaging 1
  • Delayed contrast phase for comprehensive evaluation 1
  • Noncontrast images when intramural hematoma (IMH) is suspected 1

Evidence Supporting Combined Imaging

• The American College of Radiology guidelines specifically state that "extension of CTA to include the chest, abdomen, and pelvis is standard in evaluation of vascular pathology" 1
• A meta-analysis of studies examining CTA for aortic dissection showed a pooled sensitivity of 100% and specificity of 98% 1
• When CTA is used as a first-line test, the International Registry of Acute Aortic Dissection reported a sensitivity of 93% for diagnosing dissection 1

When Limited Chest-Only CTA May Be Appropriate

• If serial studies have previously confirmed that pathology remains limited to the thorax, chest-only imaging may be considered 1
• However, this approach should be taken with caution, as extension of pathology can occur over time 1

Pitfalls to Avoid

• Performing chest-only CTA when evaluating suspected aortic dissection may miss extension into abdominal vessels 1
• Omitting ECG gating can lead to motion artifacts that compromise evaluation of the ascending aorta 1
• Failing to include noncontrast images when IMH is suspected can reduce diagnostic accuracy (studies show significantly improved sensitivity, specificity, and accuracy with dual-phase CTA including noncontrast series) 1

By following these evidence-based recommendations, you can ensure optimal imaging for accurate diagnosis, risk assessment, and treatment planning for aortic pathology.