Impact of computed tomography (CT)-derived fractional flow reserve on reader confidence for interpretation of coronary CT angiography.

PURPOSE: To assess the impact of computed tomography-derived fractional flow reserve (FFRCT ) on reader confidence and reader time for interpretation of coronary computed tomography angiography (CCTA).

MATERIAL AND METHODS: This IRB-approved, HIPAA-compliant, consent waivered, quality-improvement study included 50 patients (23 women, age 67 ± 12years, body mass index 28.7 ± 5.3 kg/m2 ). CCTA was acquired on 2nd and 3rd generation dual-source MDCT with use of beta-blockers and nitroglycerin, and FFRCT was calculated (HeartFlow,Redwood City,CA). Two readers with experience level COCATS2 (Core- Cardiology-Training-Symposium) and two with COCATS3 assessed severity of epicardial coronary artery disease (CAD) using CCTA alone and CCTA with FFRCT . Reader confidence for CAD and hemodynamically significant stenosis (HS) was rated on a 4-point Likert-scale (1=high, 2=good, 3=limited, 4=none) for the four major epicardial coronary artery (CA) vessels. Time to interpret was recorded.

RESULTS: The severity of CAD in the cohort population was CAD-RADS1 (Coronary-Artery-Disease Reporting-and-Data-System) n = 15, CAD-RADS2 n = 8, CAD-RADS3 n = 11, and CAD-RADS4A n = 16. Sixty-three CA in 30 patients had minimal FFRCT values  ≤0.8. Reader confidence when using FFRCT increased for CAD and HS (p = 0.0001) with a reduction of "non-confident" patient reads (rank 3&4) by 27% and 75%, respectively. The change in confidence was not associated with CAD-RADS (p = 0.1) but correlated with reader experience (p < 0.001). The median time-to-read a CCTA study decreased by 5 min when FFRCT was available (p < 0.001).

CONCLUSION: Interpretation of CCTA in conjunction with FFRCT improved reader for assessment of severity of CAD and HS with reduction of "non-confident" reads and decreased the median time-to-interpretation of a CCTA.