New method of measuring coronary diameter by electron-beam computed tomographic angiography using adjusted thresholds...

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.

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).

The abbreviated formula provided a rapid, accurate method for measurements independent of arterial enhancement.