Selection
Initial Assessment: Transthoracic echocardiography (TTE) is recommended at diagnosis to assess aortic valve anatomy, valve function, and thoracic aortic diameters. CT or MRI is reasonable for comprehensive anatomic assessment. [1]
Surveillance Imaging: The choice depends on aneurysm location: [2]
Aortic root/proximal ascending aorta: TTE can be used if measurements correlate well with CT/MRI
Mid-ascending, arch, or descending thoracic aorta: CT or MRI is recommended
MRI is preferred for long-term surveillance to avoid cumulative radiation exposure from serial CT scans [1][3]
Surveillance Intervals
Size-Based Recommendations: [2-4]
<4.0 cm: Every 2-3 years if stable
4.0-4.4 cm: Every 2 years
4.5-4.9 cm: Annually
5.0-5.4 cm: Every 6-12 months (consider optimization for repair)
≥5.5 cm: Surgical evaluation indicated
Initial surveillance: Obtain follow-up imaging at 6-12 months after diagnosis to establish the growth rate. If stable, adjust interval based on size. [1]
Growth rate considerations: Descending thoracic aneurysms grow faster than ascending aneurysms (mean 2.76 mm/year vs 1 mm/year overall). Growth accelerates exponentially above 4.5 cm diameter. [3-4]