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FIG 5. A and B, Selective angiogram of the left carotid artery (A) shows a stenosis in the proximal ICA (arrow), which was measured to be 58%. Three-dimensional rotational angiogram of the same carotid artery (B), which was reconstructed from the 80 original projections, shows the stenosis (arrow) without overlapping arterial branches. Note that only the original projection images (not shown) instead of 3D reconstructions were used in the study as the reference for CT angiography. The stenosis degree was measured to be 69% on the original rotational angiograms (not shown).
C and D, CT angiographic cross-sectional (C) and oblique sagittal (D) MPR images show no mural calcification at the maximum stenosis (arrow). White lines on the carotid artery indicate the manually measured diameters of the vessels. Cross-sectional MPR image (C) shows the noncircularity of the lumen at the stenosed level. With CT angiographic measurements by the two radiologists, the stenosis degree was underestimated by 28–38% on the cross-sectional MPR images compared with rotational angiographic measurements. The underestimation rate was lower (2–18%) with use of oblique sagittal MPR images. In this particular case, the stenosis degree was visually estimated to be 70% with CT angiography
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