Published online before print November 13, 2002, 10.1148/radiol.2261011211
Coronary Artery: Quantitative Evaluation of Normal Diameter Determined with Electron-Beam CT Compared with Cine Coronary Angiography—Initial Experience1
Nobusada Funabashi, MD,
Yoshiki Kobayashi, MD,
Mark Perlroth, PhD and
Geoffrey D. Rubin, MD
1 From the Department of Radiology, Stanford University School of Medicine, Calif (N.F., M.P., G.D.R.); and First Department of Internal Medicine, Osaka City University, Japan (Y.K.). From the 1999 RSNA scientific assembly. Received July 17, 2001; revision requested September 10; revision received February 20, 2002; accepted February 15. Address correspondence to N.F., Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine (M4), 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan (e-mail: nobusada@ma.kcom.ne.jp).
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Figure 1. Quantitative coronary angiogram shows the 30° right anterior oblique projection of the left coronary arteries. Lines indicate the manual tracing.
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Figure 2a. Fixed-threshold vessel diameter method, which simulates shaded surface display with electron-beam CT. (a) Transverse source image obtained with contrast-enhanced electron-beam CT. Line indicates long axis of LAD branch with which we measured vessel diameters. (b) Oblique planar image parallel to long axis of LAD branch. Line indicates axis perpendicular to long axis of vessel. Diameters were measured perpendicular to the median centerline of the vessel. Oblique planar reformations were generated parallel to the long axis of the vessel, which approximates the oblique projections analyzed with cine coronary angiography. (c) Oblique planar image perpendicular to long axis of LAD branch. A threshold was applied to the entire data set that reduced the gray scale to black and white. This was accomplished by setting display window width to 0 and display window level to 80, 100, 120, or 140 HU (in this case, 120 HU). Vessel diameters were measured at each measurement point along the same direction as were measured on the coronary angiograms. A = anterior, R = right.
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Figure 2b. Fixed-threshold vessel diameter method, which simulates shaded surface display with electron-beam CT. (a) Transverse source image obtained with contrast-enhanced electron-beam CT. Line indicates long axis of LAD branch with which we measured vessel diameters. (b) Oblique planar image parallel to long axis of LAD branch. Line indicates axis perpendicular to long axis of vessel. Diameters were measured perpendicular to the median centerline of the vessel. Oblique planar reformations were generated parallel to the long axis of the vessel, which approximates the oblique projections analyzed with cine coronary angiography. (c) Oblique planar image perpendicular to long axis of LAD branch. A threshold was applied to the entire data set that reduced the gray scale to black and white. This was accomplished by setting display window width to 0 and display window level to 80, 100, 120, or 140 HU (in this case, 120 HU). Vessel diameters were measured at each measurement point along the same direction as were measured on the coronary angiograms. A = anterior, R = right.
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Figure 2c. Fixed-threshold vessel diameter method, which simulates shaded surface display with electron-beam CT. (a) Transverse source image obtained with contrast-enhanced electron-beam CT. Line indicates long axis of LAD branch with which we measured vessel diameters. (b) Oblique planar image parallel to long axis of LAD branch. Line indicates axis perpendicular to long axis of vessel. Diameters were measured perpendicular to the median centerline of the vessel. Oblique planar reformations were generated parallel to the long axis of the vessel, which approximates the oblique projections analyzed with cine coronary angiography. (c) Oblique planar image perpendicular to long axis of LAD branch. A threshold was applied to the entire data set that reduced the gray scale to black and white. This was accomplished by setting display window width to 0 and display window level to 80, 100, 120, or 140 HU (in this case, 120 HU). Vessel diameters were measured at each measurement point along the same direction as were measured on the coronary angiograms. A = anterior, R = right.
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Figure 3a. LDP measurement method. Plot shows the voxel values along a line that is perpendicular to the vessel at each measurement site. The LDP was smoothed by means of linear interpolation between voxels (dotted line). The baseline of the LDP was established as (a) the epicardial fat immediately adjacent to the vessel on both sides or (b) the epicardial fat on one side and the myocardium on the other side. For each side of the LDP, the width was measured from the point that represented 50%, 60%, 70%, or 80% of the maximum CT value on each side.
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Figure 3b. LDP measurement method. Plot shows the voxel values along a line that is perpendicular to the vessel at each measurement site. The LDP was smoothed by means of linear interpolation between voxels (dotted line). The baseline of the LDP was established as (a) the epicardial fat immediately adjacent to the vessel on both sides or (b) the epicardial fat on one side and the myocardium on the other side. For each side of the LDP, the width was measured from the point that represented 50%, 60%, 70%, or 80% of the maximum CT value on each side.
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Figure 4. Scatterplot of absolute errors for vessel diameter versus the angles at which the measurements were made relative to the through-plane scan axis. With the 70% LDP method, the mean (-0.03) and SD (0.98) of the absolute errors for all vessels was the closest to zero and was the smallest of those obtained with each of the four fixed-threshold and four LDP methods.
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Figure 5a. Scatterplots of absolute errors with (a) 100-HU fixed threshold and (b) 70% LDP methods versus the peak CT values. In a and b, the absolute errors were correlated with the peak CT values (R2 = 0.34-0.56, P < .01 and R2 = 0.0003-0.0133, P value not significant, respectively).
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Figure 5b. Scatterplots of absolute errors with (a) 100-HU fixed threshold and (b) 70% LDP methods versus the peak CT values. In a and b, the absolute errors were correlated with the peak CT values (R2 = 0.34-0.56, P < .01 and R2 = 0.0003-0.0133, P value not significant, respectively).
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Figure 6a. (a) Scatterplot of absolute errors for diameters with the 70% LDP method versus quantitative coronary angiography (QCA). Absolute errors for diameters with the former correlated with the latter (R2 = 0.23-0.43, P < .01). (b) Scatterplot of the absolute errors for diameters with the combined LDP method versus coronary angiography. Absolute errors of diameters with the former correlated with the latter (R2 = 0.04, P < .01).
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Figure 6b. (a) Scatterplot of absolute errors for diameters with the 70% LDP method versus quantitative coronary angiography (QCA). Absolute errors for diameters with the former correlated with the latter (R2 = 0.23-0.43, P < .01). (b) Scatterplot of the absolute errors for diameters with the combined LDP method versus coronary angiography. Absolute errors of diameters with the former correlated with the latter (R2 = 0.04, P < .01).
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Figure 7a. Scatterplots of absolute errors for diameters with (a) the 100-HU fixed-threshold, (b) 70% LDP, and (c) combined LDP measurements versus the averages of the measurements with electron-beam CT and quantitative coronary angiography (QCA), according to the analysis of Bland and Altman (10). These three methods were chosen because the means of absolute errors for all vessels were close to zero (0.10, -0.03, and 0.01 mm, respectively). Two SDs of the absolute errors for all vessels were 3.20, 1.96, and 1.60 mm, respectively.
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Figure 7b. Scatterplots of absolute errors for diameters with (a) the 100-HU fixed-threshold, (b) 70% LDP, and (c) combined LDP measurements versus the averages of the measurements with electron-beam CT and quantitative coronary angiography (QCA), according to the analysis of Bland and Altman (10). These three methods were chosen because the means of absolute errors for all vessels were close to zero (0.10, -0.03, and 0.01 mm, respectively). Two SDs of the absolute errors for all vessels were 3.20, 1.96, and 1.60 mm, respectively.
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Figure 7c. Scatterplots of absolute errors for diameters with (a) the 100-HU fixed-threshold, (b) 70% LDP, and (c) combined LDP measurements versus the averages of the measurements with electron-beam CT and quantitative coronary angiography (QCA), according to the analysis of Bland and Altman (10). These three methods were chosen because the means of absolute errors for all vessels were close to zero (0.10, -0.03, and 0.01 mm, respectively). Two SDs of the absolute errors for all vessels were 3.20, 1.96, and 1.60 mm, respectively.
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Copyright © 2003 by the Radiological Society of North America.
