Measuring the abdominal aorta with ultrasonography and computed tomography - difference and variability.

Abstract

The aim of this study was to estimate the agreement between ultrasonography (US) and computed tomography (CT) in the measurement of aortic diameter in subjects with and without abdominal aortic aneurysms (AAA). Sixty-one subjects were investigated, 33 with a diameter >30mm and 28 with a diameter <30mm. Difference and variabily anteroposterior (AP) and transverse (TR) diameters were analysed. In non-aneurysmal aortas US gave larger AP: 2.8mm (95% CI 1.7-4.0) and TR: 3.8mm (2.3-5.3) diameter. In AAAs the mean diameter did not differ significantly. In non-aneurysmal aortas we expect 95% of differences to be <5.7mm in AP and <7.6mm in TR measurements. In aneurysmal aortas we expect 95% of differences to be <8.0mm in AP and <10.6mm in TR measurements. The difference and variability between US and CT varies depends on the diameter of the aorta and how it is measured. These differences have importance for clinical practice and for research.