Clinical validation of three-dimensional ultrasound for abdominal aortic aneurysm

Three-dimensional ultrasound (3D-US) examination is a relatively new modality that can be used for abdominal aortic aneurysm (AAA) surveillance, and may offer improved reproducibility over conventional two-dimensional ultrasound (2D-US) examination. The aim of this study was to evaluate the interoperator reproducibility of maximum anterior-to-posterior diameter by nonphysician ultrasound technicians in a typical vascular laboratory setting, on patients with infrarenal AAAs using 3D-US and 2D-US examination.

A total of 134 consecutive patients with asymptomatic infrarenal AAAs were screened. Of the 134 patients, 28 (21%) were screen failures. From the remaining 106 patients, 3 (2.8%) had missing data and 13 (12.3%) had technically unacceptable image quality. As a result, 90 patients were included for final analysis. Ultrasound image acquisitions were performed during the single visit. The 2D-US images were evaluated at the time of examination by the respective ultrasound technicians who acquired them. All 3D-US images were evaluated offline by both ultrasound technicians after a wash-out period of at least 6 weeks.

Excellent interoperator reproducibility was observed for measuring maximum diameter using 3D-US (intraclass correlation coefficient, 0.97), and good agreement among ultrasound technicians (mean difference, -0.08 mm; limits of agreement, -3.17; 3.00 mm). When using 3D-US examination, 74 of the 90 patients (82%) were estimated within 2 mm of interoperator variability. Of 90 patients, 52 (58%) were estimated to be within the same variability by 2D-US examination. Estimating AAA diameter using 3D-US was superior to 2D-US with respect to interoperator reproducibility.

Both 3D-US and 2D-US examination demonstrated good reproducibility among two vascular ultrasound technicians with superior agreement from 3D-US examination. The present results support the broader use of 3D-US in standard AAA surveillance programs.