Accuracy of coronary computed tomography angiography vs intravascular ultrasound for evaluation of vessel area

Implications of computed tomography reconstruction algorithms on coronary atheroma quantification: Comparison with intravascular ultrasound

BACKGROUND

Advances in coronary computed tomography angiography (CCTA) reconstruction algorithms are expected to enhance the accuracy of CCTA plaque quantification. We aim to evaluate different CCTA reconstruction approaches in assessing vessel characteristics in coronary atheroma using intravascular ultrasound (IVUS) as the reference standard.

METHODS

Matched cross-sections (n ​= ​7241) from 50 vessels in 15 participants with chronic coronary syndrome who prospectively underwent CCTA and 3-vessel near-infrared spectroscopy-IVUS were included. Twelve CCTA datasets per patient were reconstructed using two different kernels, two slice thicknesses (0.75 ​mm and 0.50 ​mm) and three different strengths of advanced model-based iterative reconstruction (IR) algorithms. Lumen and vessel wall borders were manually annotated in every IVUS and CCTA cross-section which were co-registered using dedicated software. Image quality was sub-optimal in the reconstructions with a sharper kernel, so these were excluded. Intraclass correlation coefficient (ICC) and repeatability coefficient (RC) were used to compare the estimations of the 6 CT reconstruction approaches with those derived by IVUS.

RESULTS

Segment-level analysis showed good agreement between CCTA and IVUS for assessing atheroma volume with approach 0.50/5 (slice thickness 0.50 ​mm and highest strength 5 ADMIRE IR) being the best (total atheroma volume ICC: 0.91, RC: 0.67, p ​< ​0.001 and percentage atheroma volume ICC: 0.64, RC: 14.06, p ​< ​0.001). At lesion-level, there was no difference between the CCTA reconstructions for detecting plaques (accuracy range: 0.64-0.67; p ​= ​0.23); however, approach 0.50/5 was superior in assessing IVUS-derived lesion characteristics associated with plaque vulnerability (minimum lumen area ICC: 0.64, RC: 1.31, p ​< ​0.001 and plaque burden ICC: 0.45, RC: 32.0, p ​< ​0.001).

CONCLUSION

CCTA reconstruction with thinner slice thickness, smooth kernel and highest strength advanced IR enabled more accurate quantification of the lumen and plaque at a segment-, and lesion-level analysis in coronary atheroma when validated against intravascular ultrasound.

CLINICALTRIALS

gov (NCT03556644).

A simple coronary blood flow model to study the collateral flow index

In this work, we present a novel modeling framework to investigate the effects of collateral circulation into the coronary blood flow physiology. A prototypical model of the coronary tree, integrated with the concept of Collateral Flow Index (CFI), is employed to gain insight about the role of model parameters associated with the collateral circuitry, which results in physically-realizable solutions for specific CFI data. Then, we discuss the mathematical feasibility of pressure-derived CFI, anatomical implications and practical considerations involving the estimation of model parameters in collateral connections. A sensitivity analysis is carried out, and the investigation of the impact of the collateral circulation on FFR values is also addressed.

Value of Transverse Groove on the Earlobe and Hair Growth on the Ear to Predict the Risk for Coronary Artery Disease and Its Severity among Iranian Population, in Tehran City

Background:

The use of phenotypic parameters along with other noninvasive diagnostic modality can lead to early diagnosis of coronary artery disease (CAD) and prevent its life-threatening outcome. Recently, the application of head and face components for assessing the risk for CAD much attention has been paid. The present study aimed to assess the relationship between ear characteristics (transverse groove on the earlobe and hair growth on the ear) and the risk for CAD and its severity among Iranian patients.

Materials and Methods:

In this cross-sectional study, the study population consisted of 105 consecutive patients with suspected CAD undergoing coronary angiography. The severity of CAD was determined by the number of disease vessels as well as the presence of left main lesions assessed by coronary angiography. All patients were examined to evaluate the appearance of ear regarding the presence of transverse groove on the earlobe and hair growth on the ear.

Results:

Comparing cardiovascular parameters across the groups with and without transverse groove on the earlobe showed a higher rate of CAD as well as the higher number of involved coronary arteries than in the groups without transverse groove on the earlobe. Similarly, the presence of CAD and its higher severity were more revealed in patients with hair growth on the ear as compared to the group without this phenotype. According to multivariable logistic regression analysis and with the presence of baseline parameters, the presence of transverse groove on the earlobe and hair growth on the ear increased the risk for CAD by 2.4 and 4.4 fold, respectively.

Conclusion:

Along with classic cardiovascular risk factors, the role of growing hair on the ear and transverse groove on the ear to predict high risk for CAD should be considered.

Apixaban versus warfarin in evaluation of progression of atherosclerotic and calcified plaques (prospective randomized trial)

Warfarin has been showed to increase vascular calcification. Apixaban, a direct factor Xa inhibitor, has no interaction with vitamin K and its effect on coronary plaques is unknown. We randomized and compared warfarin and apixaban on progression of coronary atherosclerotic plaques measured by coronary computed tomographic angiography in 66 subjects with non-valvular atrial fibrillation over the period of one-year follow up. There was significant higher total, calcified and low attenuation plaque volume in the group randomized to warfarin as compared to apixaban (all P < .05). Greater volume of total (β₂ = 28.54; P = .03), low attenuation plaque (β₂ = 3.58; P = .02) and calcified (β₂ = 14.10; P = .005) plaque progression was observed in the VKA_group.

Invasive or non-invasive imaging for detecting high-risk coronary lesions?

INTRODUCTION

Advances in our understanding about atherosclerotic evolution have enabled us to identify specific plaque characteristics that are associated with coronary plaque vulnerability and cardiovascular events. With constant improvements in signal and image processing an arsenal of invasive and non-invasive imaging modalities have been developed that are capable of identifying these features allowing in vivo assessment of plaque vulnerability. Areas covered: This review article presents the available and emerging imaging modalities introduced to assess plaque morphology and biology, describes the evidence from the first large scale studies that evaluated the efficacy of invasive and non-invasive imaging in detecting lesions that are likely to progress and cause cardiovascular events and discusses the potential implications of the in vivo assessment of coronary artery pathology in the clinical setting. Expert commentary: Invasive imaging, with its high resolution, and in particular hybrid intravascular imaging appears as the ideal approach to study the mechanisms regulating atherosclerotic disease progression; whereas non-invasive imaging is expected to enable complete assessment of coronary tree pathology, detection of high-risk lesions, more accurate risk stratification and thus to allow a personalized treatment of vulnerable patients.

A head-to-head comparison between CT- and IVUS-derived coronary blood flow models

The goal of this work is to compare coronary hemodynamics as predicted by computational blood flow models derived from two imaging modalities: coronary computed tomography angiography (CCTA) and intravascular ultrasound integrated with angiography (IVUS). Criteria to define boundary conditions are proposed to overcome the dissimilar anatomical definition delivered by both modalities. The strategy to define boundary conditions is novel in the present context, and naturally accounts for the flow redistribution induced by the resistance of coronary vessels. Hyperemic conditions are assumed to assess model predictions under stressed hemodynamic environments similar to those encountered in Fractional Flow Reserve (FFR) calculations. As results, it was found that CCTA models predict larger pressure drops, higher average blood velocity and smaller FFR. Concerning the flow rate at distal locations in the major vessels of interest, it was found that CCTA predicted smaller flow than IVUS, which is a consequence of a larger sensitivity of CCTA models to coronary steal phenomena. Comparisons to in-vivo measurements of FFR are shown.

Fast Marching and Runge-Kutta Based Method for Centreline Extraction of Right Coronary Artery in Human Patients

The CT angiography (CTA) is a clinically indicated test for the assessment of coronary luminal stenosis that requires centerline extractions. There is currently no centerline extraction algorithm that is automatic, real-time and very accurate. Therefore, we sought to (i) develop a hybrid approach by incorporating fast marching and Runge-Kutta based methods for the extraction of coronary artery centerlines from CTA; (ii) evaluate the accuracy of the present method compared to Van's method by using ground truth centerline as a reference; (iii) evaluate the coronary lumen area of our centerline method in comparison with the intravascular ultrasound (IVUS) as the standard of reference. The proposed method was found to be more computationally efficient, and performed better than the Van's method in terms of overlap measures (i.e., OV: [Formula: see text] vs. [Formula: see text]; OF: [Formula: see text] vs. [Formula: see text]; and OT: [Formula: see text] vs. [Formula: see text], all [Formula: see text]). In comparison with IVUS derived coronary lumen area, the proposed approach was more accurate than the Van's method. This hybrid approach by incorporating fast marching and Runge-Kutta based methods could offer fast and accurate extraction of centerline as well as the lumen area. This method may garner wider clinical potential as a real-time coronary stenosis assessment tool.

The correlation between computed tomography and duplex evaluation of autogenous vein bypass grafts and their relationship to failure

OBJECTIVE

Duplex ultrasound (DUS) imaging for vein bypass graft (VBG) surveillance is confounded by technical and physiologic factors that reduce the sensitivity for detecting impending graft failure. In contrast, three-dimensional computed tomography angiography (CTA) offers high-fidelity anatomic characterization of VBGs, but its utility in detecting at risk grafts is unknown. The current study analyzed the correlation between DUS and CTA for detection of vein graft stenosis and evaluated the relationship of the observed abnormalities to VBG failure.

METHODS

Consecutive lower extremity VBG patients underwent surveillance with concurrent DUS imaging and CTA at 1 week and at 1, 6, and 12 months postoperatively. A standardized algorithm was used for CT reconstruction and extraction of the lumen geometries at 1-mm intervals. At each interval, CT-derived cross-sectional areas were coregistered and correlated to DUS peak systolic velocities (PSVs) within six predesignated anatomic zones and then analyzed for outcome association. Vein graft failure was defined as pathologic change within a given anatomic zone resulting in thrombosis, amputation, or reintervention within the 6-month period after the observed time point.

RESULTS

The study recruited 54 patients, and 10 (18%) experienced failure ≤18 months of implantation. The expected inverse relationship between cross-sectional area and PSV was only weakly correlated (Spearman rank coefficient = -0.19). Moderate elevations in the PSV ratio (PSVr; 2-3.5) were frequently transient, with 14 of 18 grafts (78%) demonstrating ratio reduction on subsequent imaging. A PSVr ≥3.5 was associated with a 67% failure rate. CT stenosis <50% was highly correlated with success (0 failures); however, high-grade (>80%) CT stenosis was more likely to succeed than to fail (25%). Significant discordance between CT and DUS was found in 18 patients. Although 14 of these patients had CT stenosis >70% with a PSVr <3.5, subsequent failure occurred in only two. Conversely, graft failure occurred in three of four patients with CT stenosis <70% but PSVr >3.5. Focused analysis of these patients using computational fluid dynamic modeling demonstrated that vein side branches, local tortuosity, regional diameter variations, and venovenostomies were the drivers of these discrepancies.

CONCLUSIONS

This analysis demonstrated that a PSVr ≥3.5 is strongly correlated with VBG failure, whereas the natural history of moderately elevated PSVr (2-3.5) is largely clinically benign. Although minimum stenosis on the CT scan was highly predictive of success, high-grade CT stenosis was infrequently associated with failure. The interaction of anatomic features with the local flow dynamics was identified as the primary confounder for a direct correlation between CT and DUS imaging.

Virtual intravascular endoscopy visualization of calcified coronary plaques: a novel approach of identifying plaque features for more accurate assessment of coronary lumen stenosis

This study was conducted to investigate the feasibility of using 3D virtual intravascular endoscopy (VIE) as a novel approach for characterization of calcified coronary plaques with the aim of differentiating superficial from deep calcified plaques, thus improving assessment of coronary stenosis.A total of 61 patients with suspected coronary artery disease were included in the study. Minimal lumen diameter (MLD) was measured and compared between coronary CT angiography (CCTA) (≥64-slice) and invasive coronary angiography (ICA) with regard to the measurement bias, whereas VIE findings were correlated with CCTA with respect to the diagnostic performance of coronary stenosis and the area under the curve (AUC) by receiver-operating characteristic curve analysis (ROC).In all 3 coronary arteries, the CCTA consistently underestimated the MLD relative to the ICA (P < 0.001). On a per-vessel assessment, the sensitivity, specificity, positive predictive value, and negative predictive value and 95% confidence interval (CI) were 94% (95% CI: 61%, 100%), 27% (95% CI: 18%, 38%), 33% (95% CI: 23%, 43%), and 92% (95% CI: 74%, 99%) for CCTA, and 100% (95% CI: 89%, 100%), 85% (95% CI: 75%, 92%), 71% (95% CI: 56%, 84%), and 100% (95% CI: 95%, 100%) for VIE, respectively. The AUC by ROC analysis for VIE demonstrated significant improvement in analysis of left anterior descending calcified plaques compared with CCTA (0.99 vs 0.60, P < 0.001), with better performance in the left circumflex and right coronary arteries (0.98 vs 0.84 and 0.77 vs 0.77, respectively; P = 0.07 and P = 0.96, respectively). There are no significant differences between 64-, 128-, and 640-slice CCTA and VIE in terms of sensitivity, specificity, positive and negative predictive value in the diagnosis of coronary stenosis.This study shows the feasibility of using VIE for characterizing morphological features of calcified plaques, therefore, significantly improving assessment of coronary stenosis.