How is the size of the aorta most accurately measured on CT or MRI?
Drawing a line perpendicular to the course of the aorta is required for accurate measurement of the aortic diameter. This is often different than the cross-section of the aorta commonly seen on axial CT and MR images because these images are axial to the patient’s body, not axial relative to the course of the aorta. Accurate measurement, especially of a tortuous vessel, often requires multiplanar or three-dimensional reformatting
