Noninvasive Coronary Imaging Using Electron Beam CT: Surface Rendering Versus Volume Rendering

Noninvasive Coronary Imaging Using Electron Beam CT: Surface Rendering Versus Volume Rendering

P. M. A. van Ooijen¹, R. J. M. van Geuns², B. J. W. M. Rensing², A. H. H. Bongaerts¹, P. J. de Feyter² and M. Oudkerk¹

^¹ Department of Radiology, University Hospital Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.
^² Department of Cardiology, University Hospital Rotterdam, Thoraxcentre, P. O. Box 2040, 3000 CA, Rotterdam, The Netherlands.

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Fig. 1. —Opacity curve and histogram for volume rendering of coronary arteries. Typical CT histogram shows number of voxels with specific voxel values (CT number). Each CT number can be assigned certain tissue composition. Default tissue compositions consist of air, fat, soft tissue, and bone, with each tissue represented by specific peak in histogram. Tissue composition is identical for each CT scan. Line representing opacity shows maximum opacity for bone and contrast-enhanced blood and low opacity ( ${approx}$ 30-40%) for fat and soft tissue. Air is fully transparent.

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Fig. 2A. —Three-dimensional electron beam CT scans of coronary artery. Ao = aorta, RVOT = right ventricular outflow tract, LAD = left anterior descending coronary artery, RCX = right coronary artery. Surface rendering shows loss of detail, especially close to left main artery, in proximal part of left anterior descending artery, and in proximal part of intermediate branch (arrows). Area with loss of detail in left anterior descending artery was falsely rated as stenotic region. Right ventricular outflow track was hollowed out in surface rendering because of thresholding, thus showing visualization of only small part of data.

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Fig. 2B. —Three-dimensional electron beam CT scans of coronary artery. Ao = aorta, RVOT = right ventricular outflow tract, LAD = left anterior descending coronary artery, RCX = right coronary artery. Volume rendering shows no stenosis (arrowheads).

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Fig. 3A. —Electron beam CT scans obtained after venuos bypass graft surgey. Ao = aorta, CABG = coronary artery bypass graft. Surface rendering (A) and volume rendering (B) show coronary artery bypass graft.

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Fig. 3B. —Electron beam CT scans obtained after venuos bypass graft surgey. Ao = aorta, CABG = coronary artery bypass graft. Surface rendering (A) and volume rendering (B) show coronary artery bypass graft.

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Fig. 4A. —Electron beam CT scans obtained after coronary artery bypass graft surgery. Volume rendering shows lumen of coronary arteries and coronary artery bypass graft. Arrows show calcified plaques; arrowheads show surgical clips.

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Fig. 4B. —Electron beam CT scans obtained after coronary artery bypass graft surgery. Volume rendering shows calcified plaques within vessel lumen (arrows) and surgical clips (arrowheads). Contrast-enhanced blood was displayed in more transparent setting to preserve view of anatomic position and orientation of calcified plaques and clips.

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Fig. 5A. —Electron beam CT scans obtained after stent placement. Volume rendering shows coronary arteries.

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Fig. 5B. —Electron beam CT scans obtained after stent placement. More transparent volume rendering shows position of stent. Inset shows image using setting that results in more detailed visualization of stent.

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