CT Imaging Interpretation of Common Thoracic Aortic Pathology

Introduction

• Speaker: Diana Ludmanovich
• Topic: Interpretation of CT imaging for thoracic aortic pathology

Imaging Techniques

• Four approaches to imaging the aorta:
  1. Non-Contrast Enhanced Chest CT
  2. Post-Contrast Enhanced Imaging
  3. ECG Gating without Contrast
  4. ECG Gating with Contrast
• ECG-gated imaging: Provides precise measurements especially for the aorta’s size and mural pathology.

Ideal Imaging

• Combination of non-contrast and contrast-enhanced ECG-gated imaging for maximum information extraction.

Anatomy

• Ascending Aorta: From the aortic valve to before the brachiocephalic artery.
  • Important landmarks:
    • Sino-tubular Junction: Junction between the sinuses of Valsalva and the aorta.
    • Sinuses of Valsalva: Assess their maximal width.
• Aortic Arch and Descending Aorta: From the origin of the brachiocephalic artery through the thoracic arch and into the abdomen.

Measuring the Aorta

• Variability: The aorta’s size varies with age, gender, and BMI.
• Normal Diameter: Should not exceed 4 cm. Anything above is considered dilated.
• Measurement Technique:
  • Use Double Oblique Technique for accurate measurement.
  • Importance shown in cases like aortic tortuosity.

Aortic Conditions

Thoracic Aortic Aneurysm

• Etiology:
  • Ascending Aorta: Often due to connective tissue disorders, bicuspid valves, idiopathic causes, and hypertension.
  • Descending Aorta: Atherosclerosis, chronic dissection, or aortitis.
• Examples:
  • Marfan Disease: Bulbous appearance of aorta.
  • Idiopathic Aneurysm: Preservation of sino-tubular junction.
  • Bicuspid Valve: Association with ascending aortic aneurysm.
  • Aortitis (e.g., Takayasu): Involves both ascending/descending aorta and sometimes pulmonary artery.

Acute Aortic Syndrome

• Components: Classic dissection, intramural hematoma, penetrating atherosclerotic ulcer.
• Classification: Type A vs. Type B (involvement of ascending aorta).
• Diagnosis: Can be suspected on non-contrast imaging; confirmed with contrast imaging.
• Complications:
  • Rupture, hemopericardium, hemothorax, pulmonary artery dissection, and compression of the true lumen.

Intramural Hematoma

• May originate from small intramural tears.
• Complications similar to dissection, often associated with hemopericardium.

Penetrating Atherosclerotic Ulcer

• Part of acute aortic syndrome.
• Distinguished from complex atherosclerotic plaque by the ulcer going outward into the wall.

Reporting

• Key Points: Width, length, relationship to aortic arch branches, sino-tubular junction, atherosclerotic disease, etiology suggestions.

Conclusion

• High-quality, ECG-gated CT imaging is crucial for accurate assessment.
• Understanding of anatomy aids in identifying pathology and etiology.
• Structured reporting ensures comprehensive communication with referring physicians.