Aortic root dimension measurement by first-pass radionuclide angiography

A method for measuring the ascending aortic cross-sectional dimension is reported. First-pass radionuclide angiocardiography was performed in 53 patients with various cardiac diseases. The number of pixels from superior vena cava/right atrium junction to the main pulmonary artery were counted horizontally and converted to distance in centimeters. Aortic root size was also measured in these patients by M-mode echocardiography performed within 6 months of the radionuclide study. The two methods were compared by regression analysis. The correlation coefficient between the methods was 0.76, and the standard deviation of the regression was 0.23 cm. This radionuclide method has an accuracy which can be clinically useful for size assessment of the ascending aorta.