Diagnostic Value of Transluminal Attenuation Gradient for the Presence of Ischemia as Defined by Fractional Flow Reserve and Quantitative Positron Emission Tomography.

The aim of this study was to investigate the incremental diagnostic value of transluminal attenuation gradient (TAG), TAG with corrected contrast opacification (TAG-CCO), and transluminal diameter gradient (TDG) over coronary computed tomography angiography (CTA)-derived diameter stenosis alone for the identification of ischemia as defined by both the invasive reference standard fractional flow reserve (FFR) and the noninvasive reference standard quantitative positron emission tomography (PET). In addition to anatomic information obtained by coronary CTA, several functional CT parameters have been proposed to identify hemodynamically significant lesions more accurately, such as TAG, TAG-CCO, and more recently TDG. However, clinical validation studies have reported conflicting results, and a recent study has suggested that TAG may be affected by changes in vessel diameter. Patients with suspected coronary artery disease underwent coronary CTA and [ A total of 557 (91.9%) coronary arteries of 201 patients were included for analysis. TAG, TAG-CCO, and TDG did not discriminate between vessels with or without ischemia as defined by either PET or FFR. Furthermore, these parameters did not have incremental diagnostic accuracy over coronary CTA alone for the presence of ischemia as defined by PET and FFR. There was a significant correlation between TDG and TAG (r = 0.47; p < 0.001) and between TDG and TAG-CCO (r = 0.37; p < 0.001). TAG, TAG-CCO, and TDG do not provide incremental diagnostic value over coronary CTA alone for the presence of ischemia as defined by [

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