A comparison between plaque-based and vessel-based measurement for plaque component using volumetric intravascular ultrasound radiofrequency data analysis

Although percent plaque components on plaque-based measurement have been used traditionally in previous studies, the impact of vessel-based measurement for percent plaque components have yet to be studied. The purpose of this study was therefore to correlate percent plaque components derived by plaque- and vessel-based measurement using intravascular ultrasound Virtual Histology (IVUS-VH). The patient cohort comprised of 206 patients with de novo coronary artery lesions who were imaged with IVUS-VH. Age ranged from 35 to 88 years old, and 124 patients were male. Whole pullback analysis was used to calculate plaque volume, vessel volume, and absolute and percent volumes of fibrous, fibrofatty, necrotic core, and dense calcium. The plaque and vessel volumes were well correlated (r = 0.893, P < 0.001). There was a strong correlation between percent plaque components volumes calculated by plaque and those calculated by vessel volumes (fibrous; r = 0.927, P < 0.001, fibrofatty; r = 0.972, P < 0.001, necrotic core; r = 0.964, P < 0.001, dense calcium; r = 0.980, P < 0.001,). Plaque and vessel volumes correlated well to the overall plaque burden. For percent plaque component volume, plaque-based measurement was also highly correlated with vessel-based measurement. Therefore, the percent plaque component volume calculated by vessel volume could be used instead of the conventional percent plaque component volume calculated by plaque volume

Effect of statins on coronary bifurcation atherosclerosis: an intravascular ultrasound virtual histology study

This study is aimed at assessing by intravascular ultrasound virtual histology (VH-IVUS) the effect of statins on coronary bifurcation atherosclerosis in non-culprit vessels. In this non-randomized study, in 48 patients, 51 bifurcation atherosclerotic sites in non-culprit vessels without significant angiographic stenosis, underwent baseline and 12 months follow-up VH-IVUS. Patients received treatment with either simvastatin (20 mg daily, n = 24) or rosuvastatin (10 mg daily, n = 24) for the same period. VH-IVUS analysis of bifurcation lesions included the 5-mm proximal, bifurcation only (side-branch point) and 5-mm distal subsegments. Overall plaque and external elastic membrane volume decreased after 1 year (115.7 ± 35.5 to 106.1 ± 29.3 mm3, P < 0.001; and 241.0 ± 57.0 to 232.4 ± 54.2 mm3, P = 0.005, respectively). Similarly, overall dense calcium volume significantly increased (7.1 ± 5.3 to 11.0 ± 8.5 mm3, P < 0.010), while fibrous and fibrofatty volumes significantly decreased (36.9 ± 19.2 to 24.1 ± 11.7 mm3, P < 0.001; and 5.1 ± 3.8 to 2.3 ± 2.0 mm3, P < 0.001, respectively), and necrotic core volume did not change significantly (17.0 ± 11.1 to 19.8 ± 13.5 mm3, P = 0.053). There were no significant differences in compositional analysis between the simvastatin and rosuvastatin treatment groups. However, within groups, necrotic core volume significantly increased in the simvastatin treatment group (19.7 ± 13.9 to 24.3 ± 16.1 mm3, P = 0.029) but not in the rosuvastatin treatment group. (14.3 ± 6.7 to 15.6 ± 8.7 mm3, P = 0.423). The independent clinical predictors for reduction of necrotic core volume by multiple stepwise logistic regression analysis were the percent change of HDL-cholesterol level (P = 0.041, odds ratio: 1.052, 95% confidence interval (CI): 1.002 to 1.104) and the percent change of hsCRP level (P = 0.021, odds ratio: 0.989, 95% CI: 0.980 to 0.998). After 1 year, overall dense calcium volume significantly increased whilst fibrous and fibrofatty volumes significantly decreased; no significant change in the content of necrotic core was observed. Although changes in the volumes of all plaque components were not significantly different between the simvastatin and rosuvastatin treatment groups, halting of necrotic core progression was apparent in the rosuvastatin group

In-vivo, cardiac-cycle related intimal displacement of coronary plaques assessed by 3-D ECG-gated intravascular ultrasound: Exploring its correlate with tissue deformability identified by palpography

Background: ECG-gated image acquisition of intravascular ultrasound (IVUS) has been shown to provide more accurate measurements at different phases of the cardiac cycle. Objective: We sought to explore the ability dynamic assessment of ECG-gated 3-D IVUS to identify deformable regions of coronary plaques, by testing the hypothesis that at a given pressure and region, a faster displacement of the intima would correspond to high strain (soft tissue) regions assessed by palpography. Methods: ECG-gated 3-D IVUS and palpograms were acquired using 30 and 20 MHz IVUS imaging catheters respectively. Frames with high and/or low strain spots identified by palpography were randomly selected and the spots were assigned to a respective quadrant within the cross section. A color-blinded side-by-side view was performed to enable the co-localization of the same region. Subsequently, the pressure driven displacement of the intima was established for each quadrant and a binary score (significant displacement or no displacement) was decided. Results: One hundred and twenty-four quadrants were studied and the prevalence of highly deformable quadrants was low (n=7, 5.6% of the total). The sensitivity, specificity, positive predictive value and negative predictive value of 3-D ECG-gated IVUS to detect deformable quadrants as assessed by palpography were 42.9, 87.2, 16.7, and 96.2% respectively. Conclusion: In this pilot in vivo study, the intimal displacement velocity in the radial direction assessed by gray-scale 3-D ECG-gated IVUS failed to correlate with highly deformable regions. However, these preliminary findings suggest that the absence of significant displacement of the intima might be accurate to predict the absence of deformable tissue

The assessment of Shin's method for the prediction of creatinine kinase-MB elevation after percutaneous coronary intervention: an intravascular ultrasound study

Cardiac enzyme release is common after percutaneous coronary intervention (PCI). At present there is no established relationship between the quantity of necrotic core and dense calcium, as assessed by Shin's method using intravascular ultrasound virtual histology (VH-IVUS), and post-PCI creatinine kinase-MB (CK-MB) elevation. A total of 112 consecutive patients with unstable angina and a normal pre-PCI CK-MB level were imaged using VH-IVUS. Patients were divided into 2 groups according to the presence (CK-MB group, n = 22) or absence (non CK-MB group, n = 90) of a post-PCI CK-MB elevation >1.0 the upper limit of normal (3.6 ng/ml). Using Shin's method contours were drawn around the IVUS catheter (instead of the lumen), and the vessel. Mean area and volume of necrotic core and dense calcium were significantly greater in CK-MB group than in non CK-MB group (1.7 ± 0.9 mm2vs. 0.9 ± 0.6 mm2, P < 0.001; 17.2 ± 8.8 mm3vs. 8.8 ± 5.8 mm3, P < 0.001, and 0.9 ± 0.6 mm2vs. 0.4 ± 0.4 mm2, P = 0.001; 9.1 ± 5.8 mm3vs. 3.9 ± 3.7 mm3, P < 0.001, respectively). Percent necrotic core and dense calcium areas calculated by external elastic membrane (EEM) area were significantly greater in CK-MB group than in non CK-MB group (11.9 ± 5.1 vs. 6.6 ± 4.0%, P < 0.001 and 6.5 ± 4.0 vs. 3.0 ± 2.9%, P 

Reproducibility of Shin's method for necrotic core and calcium content in atherosclerotic coronary lesions treated with bioresorbable everolimus-eluting vascular scaffolds using volumetric intravascular ultrasound radiofrequency-based analysis

Although Virtual Histology intravascular ultrasound (VH-IVUS) is increasingly used in clinical research, the reproducibility of plaque composition remains unexplored in significant coronary artery and stented lesions. The purpose of this study was to assess the reproducibility of necrotic core and calcium content in atherosclerotic coronary lesions that were treated with a bioresorbable everolimus-eluting vascular scaffold (BVS) using a new measurement method (Shin's method) by VH-IVUS. Eight patients treated with a BVS (Abbott Vascular, Santa Clara, CA, USA) were analyzed with serial VH-IVUS assessments, i.e., pre- and post-stenting, and at 6 months and 2 years follow-up. A total of 32 coronary segments were imaged to evaluate the reproducibility of volumetric VH-IVUS measurements. In Shin's method, contours are drawn around the IVUS catheter (instead of the lumen) and vessel. Overall, in the imaged coronary segment, for necrotic core and dense calcium volumes, the relative intra-observer differences were 0.30 ± 0.22, 0.19 ± 0.16% for observer 1 and 0.45 ± 0.41, 0.36 ± 0.47% for observer 2, respectively. The interobserver relative differences of necrotic core and dense calcium volumes were 0.51 ± 0.79 and 0.56 ± 1.01%, respectively. The present study demonstrates a good reproducibility for both, intra-observer and interobserver measurements using Shin's method. This method is suitable for the measurement of necrotic core and dense calcium using VH-IVUS in longitudinal studies, especially studies on bioresorbable scaffolds, because the degradation process will be fully captured independently of the location of the struts and their greyscale appearance

Effect of Folic Acid Supplementation on Levels of Circulating Monocyte Chemoattractant Protein-1 and the Presence of Intravascular Ultrasound Derived Virtual Histology Thin-Cap Fibroatheromas in Patients with Stable Angina Pectoris

Background:Virtual Histology Intravascular Ultrasound (VH-IVUS) may be used to detect early signs of unstable coronary artery disease. Monocyte Chemoattractant Protein-1 (MCP-1) is linked with coronary atherosclerosis and plaque instability and could potentially be modified by folic acid treatment.Methods:In a randomized, prospective study, 102 patients with stable angina pectoris (SAP) received percutaneous coronary intervention and established medical treatment as well as either homocysteine-lowering folic acid/vitamin B12 (±B6) or placebo (±B6) for 1 year before VH-IVUS was performed. The presence of VH-Thin-Cap Fibroatheroma (VH-TCFA) in non-intervened coronary vessels was registered and serum levels of MCP-1 were measured. The patients were subsequently followed for incident myocardial infarction (MI).Results:Patients treated with folic acid/vitamin B12 had a geometric mean (SD) MCP-1 level of 79.95 (1.49) versus 86.00 (1.43) pg/mL for patients receiving placebo (p-value 0.34). VH-TCFA lesions were present in 7.8% of patients and did not differ between intervention arms (p-value 0.47). Serum levels of MCP-1 were 1.46 (95% CI 1.12 to 1.92) times higher in patients with VH-TCFA lesions than in those without (p-value 0.005). Afterwards, patients were followed for median 2.1 years and 3.8% experienced a myocardial infarction (MI), which in post-hoc Cox regression analyses was independently predicted by both MCP-1 (P-value 0.006) and VH-TCFA (p-value 0.01).Conclusions:In patients with SAP receiving established medical treatment, folic acid supplementation is not associated with either presence of VH-TCFA or levels of MCP-1. MCP-1 is however associated with VH-TCFA, a finding corroborated by increased risk for future MI.ClinicalTrials.gov Identifier: NCT00354081

Understanding mild cell disintegration of microalgae in bead mills for the release of biomolecules

Cell disintegration is, in general, the first step in the biorefinery of algae, since it allows the release of biomolecules of interest from the cells into the bulk medium. For high-value commercial applications, the disintegration process must be selective, energy efficient and mild. Developing a process with such features would demand extensive experimental effort. In the present study, we attempt to provide a tool for developing an efficient disintegration process via bead milling, by proposing a modelling strategy that allows the prediction of the kinetics of cell disintegration while having as input not only process parameters but also strain-specific parameters like cell size and cell-wall strength. The model was validated for two different algal strains (Tetraselmis suecica and Chlorella vulgaris), at various values of bead size (0.3–1 mm) and bead fillings (2.5–75%) and at two different scales of 80 and 500 mL. Since the kinetics of disintegration is proportional to the kinetics of release of biomolecules, the model can be further used for scale-up studies and to establish a window of operation to selectively target cells or metabolites of interest. Furthermore, the energy consumption in the mill was evaluated and it was found that operating at high bead fillings (>65%) is crucial to ensure an energy efficient process.publishedVersionPaid Open Acces