Comparison with computed tomography of two ultrasound devices for diagnosis of abdominal aortic aneurysm

Screening for abdominal aortic aneurysms (AAAs) in patients at risk will become more cost effective if a simple, inexpensive, and reliable ultrasound device is available. The aim of this study was to compare a 2-dimensional, handheld ultrasound device and a newly developed ultrasound volume scanner (based on bladder scan technology) with computed tomography (CT) for diagnosing AAA. A total of 146 patients (mean age 69 +/- 10 years; 127 men) were screened for the presence of AAAs (diameter >3 cm) using CT. All patients were examined with the handheld ultrasound device and the volume scanner. Maximal diameters and volumes were used for the analyses. AAAs were diagnosed by CT in 116 patients (80%). The absolute difference of aortic diameter between ultrasound and CT was <5 mm in 88% of patients. Limits of agreement between ultrasound and CT (-6.6 to 9.4 mm) exceeded the limits of clinical acceptability (+/-5 mm). An excellent correlation between ultrasound and CT was observed (r = 0.98). The correlation coefficient between the volume scanner and CT was 0.86, with agreement of 90% and kappa value of 0.73. Using an optimal cut-off value of >56 ml, defined by receiver-operating characteristic curve analysis, sensitivity, specificity, and the positive and negative predictive values of the volume scanner for detecting AAA were 90%, 90%, 97%, and 71%, respectively. In conclusion, this study shows that a 2-dimensional, handheld ultrasound device and a newly developed ultrasound volume scanner can effectively identify patients with AAAs confirmed by CT.