Aims Quantitative flow ratio (QFR) is a recently developed technique to calculate fractional flow reserve (FFR) based on 3D quantitative coronary angiography and computational fluid dynamics,... Show moreAims Quantitative flow ratio (QFR) is a recently developed technique to calculate fractional flow reserve (FFR) based on 3D quantitative coronary angiography and computational fluid dynamics, obviating the need for a pressure-wire and hyperaemia induction. QFR might be used to guide patient selection for FFR and subsequent percutaneous coronary intervention (PCI) referral in hospitals not capable to perform FFR and PCI. We aimed to investigate the feasibility to use QFR to appropriately select patients for FFR referral.Methods and results Patients who underwent invasive coronary angiography in a hospital where FFR and PCI could not be performed and were referred to our hospital for invasive FFR measurement, were included. Angiogram images from the referring hospitals were retrospectively collected for QFR analysis. Based on QFR cut-off values of 0.77 and 0.86, our patient cohort was reclassified to 'no referral' (QFR >= 0.86), referral for 'FFR' (QFR 0.78-0.85), or 'direct PCI' (QFR <= 0.77). In total, 290 patients were included. Overall accuracy of QFR to detect an invasive FFR of <= 0.80 was 86%. Based on a QFR cut-off value of 0.86, a 50% reduction in patient referral for FFR could be obtained, while only 5% of these patients had an invasive FFR of <= 0.80 (thus, these patients were incorrectly reclassified to the 'no referral' group). Furthermore, 22% of the patients that still need to be referred could undergo direct PCI, based on a QFR cut-off value of 0.77.Conclusion QFR is feasible to use for the selection of patients for FFR referral. Show less
Quantitative flow ratio (QFR) is a novel technique to calculate fractional flow reserve (FFR), without hyperemia induction or a pressure wire, and has not yet been validated in patients with... Show moreQuantitative flow ratio (QFR) is a novel technique to calculate fractional flow reserve (FFR), without hyperemia induction or a pressure wire, and has not yet been validated in patients with diabetes mellitus (DM), who are at increased risk of coronary microvascular dysfunction. The purpose of our study was to compare the diagnostic performance of QFR in diabetic and nondiabetic patients. Patients who underwent invasive coronary angiography and subsequent invasive FFR measurement within 6 months were included. QFR was determined in all coronary arteries in which invasive FFR was performed, using a dedicated software package. Diagnostic accuracy and the area under the receiver-operating characteristic curve (AUC) were determined for QFR, using an invasive FFR cut-off value of <= 0.80 as the reference standard. In total, 320 coronary arteries from 66 (25%) diabetic and 193 (75%) nondiabetic patients were analyzed. On a vessel-based analysis, diagnostic accuracy, sensitivity, and specificity showed no significant difference between diabetic and nondiabetic patients: 88% versus 85% (p = 0.47), 71% versus 69% (p = 0.72), and 95% versus 91% (p = 0.24). Moreover, the AUC was not significantly different between patients with and without DM, 0.91 versus 0.93 (p = 0.74). The per-vessel AUC was significantly higher for QFR compared with percent diameter stenosis in both diabetic and nondiabetic patients, 0.91 versus 0.76 (p < 0.05) and 0.93 versus 0.77 (p < 0.001), respectively. In conclusion, we showed a good diagnostic performance of QFR which was independent of the presence of DM. (C) 2019 The Authors. Published by Elsevier Inc. Show less
Background: Three-dimensional (3D) quantitative coronary angiography (QCA) requires two angiographic views to restore vessel dimensions. This study investigated the impact of acquisition angle... Show moreBackground: Three-dimensional (3D) quantitative coronary angiography (QCA) requires two angiographic views to restore vessel dimensions. This study investigated the impact of acquisition angle differences (AADs) of the two angiographic views on the assessed dimensions by 3D QCA. Methods: X-ray angiograms of an assembled brass phantom with different types of straight lesions were recorded at multiple angiographic projections. The projections were randomly matched as pairs and 3D QCA was performed in those pairs with AAD larger than 25 degrees. The lesion length and diameter stenosis in three different lesions, a circular concentric severe lesion (A), a circular concentric moderate lesion (B), and a circular eccentric moderate lesion (C), were measured by 3D QCA. The acquisition protocol was repeated for a silicone bifurcation phantom, and the bifurcation angles and bifurcation core volume were measured by 3D QCA. The measurements were compared with the true dimensions if applicable and their correlation with AAD was studied. Results: 50 matched pairs of angiographic views were analyzed for the brass phantom. The average value of AAD was 48.0 +/- 14.1 degrees. The percent diameter stenosis was slightly overestimated by 3D QCA for all lesions: A (error 1.2 +/- 0.9%, P < 0.001); B (error 0.6 +/- 0.5%, P < 0.001); C (error 1.1 +/- 0.6%, P < 0.001). The correlation of the measurements with AAD was only significant for lesion A (R-2 = 0.151, P = 0.005). The lesion length was slightly overestimated by 3D QCA for lesion A (error 0.06 +/- 0.18 mm, P = 0.026), but well assessed for lesion B (error -0.00 +/- 0.16 mm, P = 0.950) and lesion C (error -0.01 +/- 0.18 mm, P = 0.585). The correlation of the measurements with AAD was not significant for any lesion. Forty matched pairs of angiographic views were analyzed for the bifurcation phantom. The average value of AAD was 49.1 +/- 15.4 degrees. 3D QCA slightly overestimated the proximal angle (error 0.4 +/- 1.1 degrees, P = 0.046) and the distal angle (error 1.5 +/- 1.3 degrees, P < 0.001). The correlation with AAD was only significant for the distal angle (R-2 = 0.256, P = 0.001). The correlation of bifurcation core volume measurements with AAD was not significant (P = 0.750). Of the two aforementioned measurements with significant correlation with AAD, the errors tended to increase as AAD became larger. Conclusions: 3D QCA can be used to reliably assess vessel dimensions and bifurcation angles. Increasing the AAD of the two angiographic views does not increase accuracy and precision of 3D QCA for circular lesions or bifurcation dimensions. (C) 2011 Wiley-Liss, Inc. Show less
Aims: To propose and validate a novel approach to determine the optimal angiographic viewing angles for a selected coronary (target) segment from X-ray coronary angiography, without the need to... Show moreAims: To propose and validate a novel approach to determine the optimal angiographic viewing angles for a selected coronary (target) segment from X-ray coronary angiography, without the need to reconstruct the entire coronary tree in three-dimensions (3D), such that subsequent interventions are carried out from the best view. Methods and results: The approach starts with standard quantitative coronary angiography (QCA) of the target vessel in two angiographic views. Next, the target vessel is reconstructed in 3D, and in a very simple and intuitive manlier, the possible overlap of the target vessel and other vessel segments can be assessed, resulting in the best view with minimum foreshortening and overlap. A retrospective study including 67 patients was set up for the validation. The overlap prediction result was compared with the true overlap on the available angiographic views (TEST views). The foreshortening for the views proposed by the new approach software viewing angle (SVA) and the views used during the stent deployment software viewing angle (EVA) were compared. Two experienced interventional cardiologists visually evaluated the success of SVA with respect to EVA. The evaluation results were graded into five values ranging from -2 to 2. The overlap prediction algorithm successfully predicted the overlap condition for all 235 TEST views. EVA was associated with more foreshortening than SVA (8.9%+/- 8.2% vs. 1.6%+/- 1.5%, p<0.001). The average evaluated point for the success of SVA was 0.94 +/- 0.80 (p<0.001), indicating that the evaluators were in favor of the optimal views determined by the proposed approach versus the views used during the actual intervention. Conclusions: The proposed approach is able to accurately and quickly determine the optimal viewing angles for the online support of coronary interventions. Show less
Over the last several years significant interest has arisen in bifurcation stenting, in particular stimulated by the European Bifurcation Club. Traditional straight vessel analysis by QCA does not... Show moreOver the last several years significant interest has arisen in bifurcation stenting, in particular stimulated by the European Bifurcation Club. Traditional straight vessel analysis by QCA does not satisfy the requirements for such complex morphologies anymore. To come up with practical solutions, we have developed two models, a Y-shape and a T-shape model, suitable for bifurcation QCA analysis depending on the specific anatomy of the coronary bifurcation. The principles of these models are described in this paper, as well as the results of validation studies carried out on clinical materials. It can be concluded that the accuracy, precision and applicability of these new bifurcation analyses are conform the general guidelines that have been set many years ago for conventional QCA-analyses. Show less
The combination/fusion of quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS)/optical coherence tomography (OCT) depends to a great extend on the co-registration of X-ray... Show moreThe combination/fusion of quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS)/optical coherence tomography (OCT) depends to a great extend on the co-registration of X-ray angiography (XA) and IVUS/OCT. In this work a new and robust three-dimensional (3D) segmentation and registration approach is presented and validated. The approach starts with standard QCA of the vessel of interest in the two angiographic views (either biplane or two monoplane views). Next, the vessel of interest is reconstructed in 3D and registered with the corresponding IVUS/OCT pullback series by a distance mapping algorithm. The accuracy of the registration was retrospectively evaluated on 12 silicone phantoms with coronary stents implanted, and on 24 patients who underwent both coronary angiography and IVUS examinations of the left anterior descending artery. Stent borders or sidebranches were used as markers for the validation. While the most proximal marker was set as the baseline position for the distance mapping algorithm, the subsequent markers were used to evaluate the registration error. The correlation between the registration error and the distance from the evaluated marker to the baseline position was analyzed. The XA-IVUS registration error for the 12 phantoms was 0.03 +/- A 0.32 mm (P = 0.75). One OCT pullback series was excluded from the phantom study, since it did not cover the distal stent border. The XA-OCT registration error for the remaining 11 phantoms was 0.05 +/- A 0.25 mm (P = 0.49). For the in vivo validation, two patients were excluded due to insufficient image quality for the analysis. In total 78 sidebranches were identified from the remaining 22 patients and the registration error was evaluated on 56 markers. The registration error was 0.03 +/- A 0.45 mm (P = 0.67). The error was not correlated to the distance between the evaluated marker and the baseline position (P = 0.73). In conclusion, the new XA-IVUS/OCT co-registration approach is a straightforward and reliable solution to combine X-ray angiography and IVUS/OCT imaging for the assessment of the extent of coronary artery disease. It provides the interventional cardiologist with detailed information about vessel size and plaque size at every position along the vessel of interest, making this a suitable tool during the actual intervention. Show less
The combination/fusion of quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS)/optical coherence tomography (OCT) depends to a great extend on the co-registration of X-ray... Show moreThe combination/fusion of quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS)/optical coherence tomography (OCT) depends to a great extend on the co-registration of X-ray angiography (XA) and IVUS/OCT. In this work a new and robust three-dimensional (3D) segmentation and registration approach is presented and validated. The approach starts with standard QCA of the vessel of interest in the two angiographic views (either biplane or two monoplane views). Next, the vessel of interest is reconstructed in 3D and registered with the corresponding IVUS/OCT pullback series by a distance mapping algorithm. The accuracy of the registration was retrospectively evaluated on 12 silicone phantoms with coronary stents implanted, and on 24 patients who underwent both coronary angiography and IVUS examinations of the left anterior descending artery. Stent borders or sidebranches were used as markers for the validation. While the most proximal marker was set as the baseline position for the distance mapping algorithm, the subsequent markers were used to evaluate the registration error. The correlation between the registration error and the distance from the evaluated marker to the baseline position was analyzed. The XA-IVUS registration error for the 12 phantoms was 0.03 ± 0.32 mm (P = 0.75). One OCT pullback series was excluded from the phantom study, since it did not cover the distal stent border. The XA-OCT registration error for the remaining 11 phantoms was 0.05 ± 0.25 mm (P = 0.49). For the in vivo validation, two patients were excluded due to insufficient image quality for the analysis. In total 78 sidebranches were identified from the remaining 22 patients and the registration error was evaluated on 56 markers. The registration error was 0.03 ± 0.45 mm (P = 0.67). The error was not correlated to the distance between the evaluated marker and the baseline position (P = 0.73). In conclusion, the new XA-IVUS/OCT co-registration approach is a straightforward and reliable solution to combine X-ray angiography and IVUS/OCT imaging for the assessment of the extent of coronary artery disease. It provides the interventional cardiologist with detailed information about vessel size and plaque size at every position along the vessel of interest, making this a suitable tool during the actual intervention. Show less
Background: Accurate on-line assessments of vessel dimensions are of utmost importance for selecting the appropriate stent size in coronary interventions. Recently a new three-dimensional... Show moreBackground: Accurate on-line assessments of vessel dimensions are of utmost importance for selecting the appropriate stent size in coronary interventions. Recently a new three-dimensional quantitative coronary angiography (3D QCA) analytical software package was developed to accurately assess the vessel dimensions for the planning and guidance of such coronary interventions. This study aimed to validate the 3D QCA software package for assessing arterial segment length by comparing with intravascular ultrasound (IVUS). In addition, the difference in the two measurements from 3D QCA and IVUS for curved segments was studied. Methods: A retrospective study including 20 patients undergoing both coronary angiography and IVUS examinations of the left coronary artery was set up for the validation. The same vessel segments of interest between proximal and distal markers were identified and measured on both angiographic and IVUS images, by the 3D QCA software and by a quantitative IVUS software package, respectively. In addition, the curvature of each of the segments of interest was assessed and the correlation between the accumulated curvature of the segment and the difference in segment lengths measured from the two imaging modalities was analyzed. Results: 37 vessel segments of interest were identified from both angiographic and IVUS images. The 3D QCA segment length was slightly longer than the IVUS segment length (15.42 +/- 6.02 mm vs. 15.12 +/- 5.81 mm, P = 0.040). The linear correlation of the two measurements was: 3D QCA Length = -0.09 + 1.03 x IVUS Length (r(2) = 0.98, P < 0.001). Bland-Altman plot showed that the difference in the two measurements was not correlated with the average of the two measurements (P = 0.141), but with the accumulated curvature of the segment (P = 0.015). After refining the difference by the correlation, the average difference of the two measurements decreased from 0.30 +/- 0.86 mm (P = 0.040) to 0.00 +/- 0.78 mm (P = 0.977). Conclusions: The 3D QCA software package can accurately assess the actual arterial segment length. The difference in segment lengths measured from 3D CICA and IVUS was correlated with the accumulated curvature of the segment. (C) 2010 Wiley-Liss, Inc. Show less
This paper presents new approaches for the assessment of the arterial and reference diameters in (cardio-)vascular X-ray images, designed to overcome the problems experienced in conventional... Show moreThis paper presents new approaches for the assessment of the arterial and reference diameters in (cardio-)vascular X-ray images, designed to overcome the problems experienced in conventional quantitative coronary and vascular angiography approaches. In single or "straight" vessel segments, the arterial and reference diameter directions were made independent of each other in order to be able to measure the minimal lumen diameter (MLD) more accurately, especially in curved vessel segments. For ostial segments, an extension of this approach was used, to allow measurement of ostial lesions in sidebranches more proximal than using conventional methods. Furthermore, two new bifurcation approaches were developed. The validation study shows that the straight segment approach results in significant smaller MLDs (on average 0.032 mm) and the ostial approach achieves on average an increase in %DS of 3.8% and an increase in lesion length of 0.59 mm due to loosening the directional constraint. The validation of our new bifurcation approaches in phantom data as well as clinical data shows only small differences between pre- and post-intervention measurements of the reference diameters outside the bifurcation core (errors smaller than 0.06 mm) and the bifurcation core area (errors smaller than 1.4% for phantom data). In summary, these new approaches have led to further improvements in the quantitative analyses of (cardio-)vascular X-ray angiographies. Show less
Three-dimensional quantitative coronary angiography (3D QCA) has been encouraged by the increasing need to better assess vessel dimensions and geometry for interventional purposes. A novel 3D QCA... Show moreThree-dimensional quantitative coronary angiography (3D QCA) has been encouraged by the increasing need to better assess vessel dimensions and geometry for interventional purposes. A novel 3D QCA system based on biplane X-ray angiograms is presented in this paper. By correcting for the isocenter offset and by improving the epipolar constraint for corresponding two angiographic projections, accurate and robust reconstruction of the vessel centerline is achieved and the reproducibility of its applications, e.g., the assessments of obstruction length and optimal viewing angle, is guaranteed. The accuracy and variability in assessing the obstruction length and optimal bifurcation viewing angle were investigated by using phantom experiments. The segment length assessed by 3D QCA correlated well with the true wire segment length (r (2) = 0.999) and the accuracy and precision were 0.04 +/- 0.25 mm (P < 0.01). 3D QCA slightly underestimated the rotation angle (difference: -1.5 degrees +/- 3.6 degrees , P < 0.01), while no significant difference was observed for the angulation angle (difference: -0.2 degrees +/- 2.4 degrees , P = 0.54). In conclusion, the new 3D QCA approach allows highly accurate and precise assessments of obstruction length and optimal viewing angle from X-ray angiography. Show less
Three-dimensional quantitative coronary angiography (3D QCA) has been encouraged by the increasing need to better assess vessel dimensions and geometry for interventional purposes. A novel 3D QCA... Show moreThree-dimensional quantitative coronary angiography (3D QCA) has been encouraged by the increasing need to better assess vessel dimensions and geometry for interventional purposes. A novel 3D QCA system based on biplane X-ray angiograms is presented in this paper. By correcting for the isocenter offset and by improving the epipolar constraint for corresponding two angiographic projections, accurate and robust reconstruction of the vessel centerline is achieved and the reproducibility of its applications, e.g., the assessments of obstruction length and optimal viewing angle, is guaranteed. The accuracy and variability in assessing the obstruction length and optimal bifurcation viewing angle were investigated by using phantom experiments. The segment length assessed by 3D QCA correlated well with the true wire segment length (r (2) = 0.999) and the accuracy and precision were 0.04 +/- A 0.25 mm (P < 0.01). 3D QCA slightly underestimated the rotation angle (difference: -1.5A degrees A A +/- A 3.6A degrees, P < 0.01), while no significant difference was observed for the angulation angle (difference: -0.2A degrees A A +/- A 2.4A degrees, P = 0.54). In conclusion, the new 3D QCA approach allows highly accurate and precise assessments of obstruction length and optimal viewing angle from X-ray angiography. Show less
