Lipid-core atherosclerotic plaques are associated with disease progression, procedural complications, and cardiac events. Coronary plaque lipid can be quantified in optical coherence tomography (OCT) pullbacks by measurement of lipid arcs and lipid lengths; parameters frequently used in clinical research, but labor intensive and subjective to analyse. In this study, we investigated the ability of quantitative attenuation, derived from intravascular OCT, to detect plaque lipid. Lipid cores are associated with a high attenuation coefficient. We compared the index of plaque attenuation (IPA), a local quantitative measure of attenuation, to the manually measured lipid score (arc and length) on OCT images, and to the plaque characterization ex-vivo. We confirmed a correlation between the IPA and lipid scores (r2 > 0.7). Comparison to histology shows that high attenuation is associated with fibroatheroma, but also with macrophage presence. IPA is a robust, reproducible, and user-independent measure that facilitates quantification of coronary lipid, a potential tool in clinical research and in guiding percutaneous coronary intervention.

Atherosclerotic plaque composition can be imaged using the optical attenuation coefficient derived from intravascular optical coherence tomography (OCT) data. The relation between optical properties and tissue type has been established on autopsy tissues. In this study, we validate an ex-vivo model for the effect of temperature and tissue fixation on optical parameters. We studied the optical attenuation of human coronary arteries at three temperatures, before and after formalin fixation. We developed an en-face longitudinal display of attenuation data of the OCT pullbacks. Using the unfixed, body-temperature condition image as a standard, and after extensive registration with other condition images, we quantify the differences in optical attenuation and the backscattered intensity. The results suggest that tissue fixation and temperature do not introduce systematic errors in studies of arterial optical properties.

The aim of this study was to investigate the relationship between the plaque free wall (PFW) measured by optical coherence tomography (OCT) and the plaque burden (PB) measured by intravascular ultrasound (IVUS). We hypothesize that measurement of the PFW could help to estimate the PB, thereby overcoming the limited ability of OCT to visualize the external elastic membrane in the presence of plaque. This could enable selection of the optimal stent-landing zone by OCT, which is traditionally defined by IVUS as a region with a PB < 40 %. PB (IVUS) and PFW angle (OCT and IVUS) were measured in 18 matched IVUS and OCT pullbacks acquired in the same coronary artery. We determined the relationship between OCT measured PFW (PFWOCT) and IVUS PB (PBIVUS) by non-linear regression analysis. An ROC-curve analysis was used to determine the optimal cut-off value of PFW angle for the detection of PB < 40 %. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated. There is a significant correlation between PFWOCT and PBIVUS (r2 = 0.59). The optimal cut-off value of the PFWOCT for the prediction of a PBIVUS < 40 % is ≥220° with a PPV of 78 % and an NPV of 84 %. This study shows that PFWOCT can be considered as a surrogate marker for PBIVUS, which is currently a common criterion to select an optimal stent-landing zone.

IPA is an unbiased reproducible measure of tissue optical properties. The fraction of pixels with attenuation coefficient ≥11 mm-1 can identify TCFA.

In non-culprit coronary segments of patients with coronary artery disease under standard medical therapy, segment-level but not patient-level minimum fibrous cap thickness increases over time, with observations of both favourable and unfavourable changes in individual segments.

No abstract

No abstract

Objectives To determine the diagnostic accuracy of whole heart 3D myocardial perfusion CMR against invasively determined FFR. Methods 55 patients referred for angiography underwent rest and adenosine stress 3D myocardial perfusion CMR at 3Tesla (3D turbo gradient echo, flip angle 15, TR 2.0 ms/TE 1.0 ms, 12 slices of 5 mm thickness, in-plane resolution 2.332.3 mm 2 , 10-fold k-space and time kt broad linear speed up technique acceleration with k-t principal component analysis). Perfusion was scored visually as on a coronary territory basis on a score from 0 to 3. Ischaemic burden was calculated by quantitative segmentation of the volume of hypoenhancement. The FFR was measured in vessels with >50% severity stenosis. Fractional flow reserve <0.75 was considered haemodynamically significant. Results Two patients were excluded (one due to claustrophobia, the other had poor image quality). From the remaining 53 patients and 159 coronary vessels, 64 underwent pressure wire assessment and 39 had an FFR<0.75. Sensitivity, specificity and diagnostic accuracy of CMR analysis per patient was 90%, 91% and 91%, respectively for the detection of significant coronary artery disease. By coronary territory the values were 79%, 92% and 88%. Conclusion 3D CMR stress perfusion can detect functionally significant coronary artery disease with excellent sensitivity, specificity and predictive values when compared with FFR. 3D CMR perfusion imaging may offer an alternative method of detecting ischaemia for the purpose of guiding revascularisation and risk stratification.Abstract 022 Figure 1 3D CMR perfusion of a patient with a proximal LAD lesion with positive fractional flow reserve (FFR¼0.61). Note the subendocardial perfusion defect from the base towards the apex.