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

Michiel J. Bom, Roel S. Driessen, Wynand J. Stuijfzand, Pieter G. Raijmakers, Cornelis C. Van Kuijk, Adriaan A. Lammertsma, Albert C. van Rossum, Niels van Royen, Juhani Knuuti, Maija Mäki, Koen Nieman, James K. Min, Jonathon A. Leipsic, Ibrahim Danad, Paul Knaapen*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Objectives: 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). Background: 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. Methods: Patients with suspected coronary artery disease underwent coronary CTA and [15O]H2O PET followed by invasive coronary angiography with FFR of all major coronary arteries. TAG, TAG-CCO, and TDG were assessed, and the incremental diagnostic value of these parameters over coronary CTA-derived diameter stenosis alone for ischemia as defined by PET (hyperemic myocardial blood flow ≤2.30 ml/min/g) and FFR (≤0.80) was determined. Results: 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). Conclusions: TAG, TAG-CCO, and TDG do not provide incremental diagnostic value over coronary CTA alone for the presence of ischemia as defined by [15O]H2O PET and/or FFR. The lack of diagnostic value of contrast enhancement-based flow estimations appears related to coronary luminal dimension variability.

Original languageEnglish
Pages (from-to)323-333
JournalJACC: Cardiovascular Imaging
Issue number2
Publication statusPublished - 1 Feb 2019

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