Measure the infrarenal neck (diameter, length, angulation, thrombus, calcification), the aneurysm, and the iliac and femoral arteries on centreline reformats — these decide whether an endograft can seal and be delivered.
Orient first
- Instructions for use (IFU) of each device define the neck requirements — typically length ≥ 10–15 mm and angulation ≤ 60° (verify the device).
- Hostile necks (short, wide, angulated, conical, thrombus-lined) predict type I endoleak.
- Access vessels need a minimum diameter for the delivery sheath.
Acquire the study
- CT angiography from the aortic arch or diaphragm to the femoral heads, ≤ 1 mm slices, centreline analysis on a workstation.
The manoeuvre
- Neck: diameter in mm outer-to-outer at the lowest renal artery and 15 mm below; neck length in mm to the aneurysm.
- Neck angulation in degrees (suprarenal and infrarenal), shape, circumferential thrombus and calcification in %.
- Aneurysm: maximal diameter in mm perpendicular to the centreline; length to the bifurcation.
- Iliac arteries: diameters and lengths of the landing zones; internal iliac patency; iliac aneurysms.
- Access: external iliac and common femoral minimal diameters in mm, tortuosity, calcification.
What confirms it
- Anatomy within device IFU, stated per parameter.
What licenses you to exclude it
- Not applicable — a planning read.
The classic misread
- Measuring on axial slices through an angulated neck (overestimates diameter).
- Missing an accessory renal artery that will be covered.