Measuring the diameter of coronary arteries on MR angiograms using spatial profile curves

The spatial profile curve of the nuclear MR intensity across the short axis of a coronary artery in an MR angiogram results in a gradual up-and-down slope lacking sharp definition, which indicates that display parameters may influence edge recognition. Therefore, our study was designed to determine the appropriate window setting and to devise a method of accurately measuring the diameter or width of the artery independent of window parameters.

The diameter of a coronary artery measured on MR coronary arteriography significantly varied with experimentally selected display parameters. When compared with the diameter on contrast-enhanced coronary arteriograms, the window center on MR angiograms at the midpoint between the peak intensity of the intravascular lumen and the background intensity and the window width of a quarter or a half of the intensity difference between the two were proven to be appropriate. The angiographic diameter corresponded to the diameter obtained at 65% +/- 9% of the peak intensity on the spatial profile curve across the short-axis MR coronary angiogram. Accordingly, 65% of the peak intensity indicates the diameter of the coronary artery. Thus, the intensity profile curve independent of the window setting provided a new method for measurement of the diameter of the coronary artery.