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Fig. 1 | EJNMMI Research

Fig. 1

From: Diagnostic accuracy of coronary opacification derived from coronary computed tomography angiography to detect ischemia: first validation versus single-photon emission computed tomography

Fig. 1

Example of CCO decrease and TAG assessment. A soft plaque with high-grade stenosis is located in the proximal LAD (a, red arrow). Two coronary ROIs (a, small white circles) are placed proximal (b) and distal of a lesion (c). Corrected contrast opacification (CCO) is calculated as the ratio of mean attenuation in the coronary ROI over the ROI in the descending aorta (large white circles). Using the lower of the two values, the difference between the proximal (b) and distal (c) was defined as CCO decrease. The transluminal attenuation gradient (TAG) was measured by ROIs at 5-mm intervals from the ostium to the distal segment where the vessel cross-sectional area decreases below 2 mm2 (a, small black circles) and defined as the linear regression coefficient between intraluminal attenuation and distance from the ostium

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