New method of measuring coronary diameter by electron-beam computed tomographic angiography using adjusted thresholds determined by calibration with aortic opacity.
BACKGROUND
In a previous study the adjusted thresholds at which the diameters of coronary arteries determined by enhanced electron-beam computed tomography (CT) scans are equal to the corresponding quantitative coronary angiography measurements were analyzed, and their correlation with maximum CT values for the vessel short axes was determined. A rapid accurate method for such measurements was sought by substituting maximum CT values for the descending aorta in the corresponding axial images for those for the short axes.


RESULTS
In 8 patients, 179 sites were measured. Means (+/- SD) of adjusted thresholds and the maximum CT values for vessel short axes and the descending aorta in the corresponding axial images for all vessels were 108 +/-66, 227+/-80, and 363+/-75 Hounsfield Unit (HU), respectively. Adjusted thresholds correlated with the maximum CT values for the corresponding vessel short axes and the descending aorta in the corresponding axial images, with R2=0.55, 0.33, p<0.01, respectively. An abbreviated formula for use of maximum CT values for the descending aorta in the corresponding axial images was y=0.5x-75 (HU) (y= adjusted threshold, x= maximum CT value for the descending aorta in the corresponding axial image).


CONCLUSIONS
The abbreviated formula provided a rapid, accurate method for measurements independent of arterial enhancement.
Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine, Japan. nobusada@ma.kcom.ne.jp
Nobusada
N
Funabashi
Yoshiki
Y
Kobayashi
Masayuki
M
Kudo
Miki
M
Asano
Kiyomi
K
Teramoto
Issei
I
Komuro
Geoffrey D
GD
Rubin
D001013:Aorta, Thoracic / Q000000981:diagnostic imaging; D002138:Calibration; D017023:Coronary Angiography / Q000379:methods*; D003331:Coronary Vessels / Q000033:anatomy & histology*; D005500:Follow-Up Studies; D016027:Heart Transplantation; D006801:Humans; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity