Author + information
- Received March 21, 2016
- Revision received July 11, 2016
- Accepted July 14, 2016
- Published online June 5, 2017.
- Brian S. Ko, MBBS (Hons), PhDa,∗ (, )
- James D. Cameron, MBBS, BE, MDa,
- Ravi K. Munnur, MBBSa,
- Dennis T.L. Wong, MBBS (Hons), PhDa,
- Yasuko Fujisawa, BScib,
- Takuya Sakaguchi, PhDb,
- Kenji Hirohata, PhDc,
- Jacqui Hislop-Jambrich, PhDd,
- Shinichiro Fujimoto, MD, PhDe,
- Kazuhisa Takamura, MD, PhDe,
- Marcus Crossett, BSca,f,
- Michael Leung, MBBS (Hons), PhDa,
- Ahilan Kuganesan, BSca,f,
- Yuvaraj Malaiapan, MBBSa,
- Arthur Nasis, MBBS (Hons), PhDa,
- John Troupis, MBBSa,f,
- Ian T. Meredith, MBBS (Hons), PhDa and
- Sujith K. Seneviratne, MBBSa
- aMonash Cardiovascular Research Centre, MonashHEART, Department of Medicine, Monash Medical Centre, Monash Health, and Monash University, Melbourne, Victoria, Australia
- bToshiba Medical Systems Corporation, Otawara, Japan
- cToshiba Corporation, Kawasaki, Japan
- dToshiba Medical Australia, North Ryde, Australia
- eDepartment of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan
- fDepartment of Diagnostic Imaging, Monash Medical Centre, Monash Health, Melbourne, Clayton, Victoria, Australia
- ↵∗Address for correspondence:
Dr. Brian S. Ko, Monash Heart, Monash Cardiovascular Research Centre, 246 Clayton Road, Clayton, 3168 VIC, Australia.
Objectives This study describes the feasibility and accuracy of a novel computed tomography (CT) fractional flow reserve (FFR) technique based on alternative boundary conditions.
Background Techniques used to compute FFR based on images acquired from coronary computed tomography angiography (CTA) are described. Boundary conditions were typically determined by allometric scaling laws and assumptions regarding microvascular resistance. Alternatively, boundary conditions can be derived from the structural deformation of coronary lumen and aorta, although its accuracy remains unknown.
Methods Forty-two patients (78 vessels) in a single institution prospectively underwent 320-detector coronary CTA and FFR. Deformation of coronary cross-sectional lumen and aorta, computed from coronary CTA images acquired over diastole, was used to determine the boundary conditions based on hierarchical Bayes modeling. CT-FFR was derived using a reduced order model performed using a standard desktop computer and dedicated software. First, 12 patients (20 vessels) formed the derivation cohort to determine optimal CT-FFR threshold with which to detect functional stenosis, defined as FFR of ≤0.8, which was validated in the subsequent 30 patients (58 vessels).
Results Derivation cohort results demonstrated optimal threshold for CT-FFR was 0.8 with 67% sensitivity and 91% specificity. In the validation cohort, CT-FFR was successfully computed in 56 of 58 vessels (97%). Compared with coronary CTA, CT-FFR at ≤0.8 demonstrated a higher specificity (87% vs. 74%, respectively) and positive predictive value (74% vs. 60%, respectively), with comparable sensitivity (78% vs. 79%, respectively), negative predictive value (89% vs. 88%, respectively), and accuracy (area under the curve: 0.88 vs. 0.77, respectively; p = 0.22). Based on Bland-Altman analysis, mean intraobserver and interobserver variability values for CT-FFR were, respectively, −0.02 ± 0.05 (95% limits of agreement: −0.12 to 0.08) and 0.03 ± 0.06 (95% limits: 0.07 to 0.19). Mean time per patient for CT-FFR analysis was 27.07 ± 7.54 min.
Conclusions CT-FFR based on alternative boundary conditions and reduced-order fluid model is feasible, highly reproducible, and may be accurate in detecting FFR ≤ 0.8. It requires a short processing time and can be completed at point-of-care. Further validation is required in large prospective multicenter settings.
- computed tomography
- coronary disease
- fractional flow reserve
- quantitative coronary angiography
Drs. Ko and Wong are funded by the National Heart Foundation of Australia and Robertson Family Scholarship. Dr. Wong is funded by the National Health and Medical Research Council of Australia. Dr. Ko has been an invited speaker at symposiums sponsored by St. Jude Medical, Pfizer, Bristol-Myers Squibb, and Eli Lilly. Ms. Fujisawa, Mr. Sakaguchi, and Dr. Hislop-Jambrich are employees of Toshiba Medical Systems Corp. Dr. Hirohata is an employee of Toshiba Corp. Dr. Meredith has received honoraria for serving on strategic advisory boards of Boston Scientific and Medtronic. Dr. Seneviratne has been an invited speaker at a Toshiba sponsored meeting. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Received March 21, 2016.
- Revision received July 11, 2016.
- Accepted July 14, 2016.
- 2017 American College of Cardiology Foundation