The prevalence of an enlarged ascending thoracic aortic diameter (AAD) diagnosed by 2-dimensional echocardiography compared with 64-slice cardiac computed tomography (MSCT) was investigated in 97 women and 117 men (mean age 65 +/- 12 years). Enlarged AADs were diagnosed in 42 of 214 patients (20%) by echocardiography and in 45 of 214 patients (21%) by MSCT (p = NS). The sensitivity, specificity, positive predictive value, and negative predictive value of echocardiography in diagnosing an enlarged AAD using MSCT were 69%, 93%, 74%, and 92%, respectively. A Bland-Altman plot showed that the agreement for AAD measured by echocardiography and MSCT was 95% inside the 2-SD limits. In conclusion, the sensitivity, specificity, positive predictive value, and negative predictive value of 2-dimensional echocardiography in diagnosing enlarged AAD using MSCT were 69%, 93%, 74%, and 92%, respectively.