Nobutaka Ikeda

Carotid artery intima-media thickness and plaque score can predict the SYNTAX score

AIMS There are few reports demonstrating a relationship between carotid artery ultrasound (carotid-US) findings and the complexity of coronary artery disease. We aimed to examine the relationship between carotid-US findings and the severity of the SYNTAX score (SXscore). METHODS AND RESULTS Subjects were 501 consecutive patients who underwent carotid-US and first coronary angiography from December 2008 to January 2011. Carotid-US was used to determine the mean common carotid artery intima-media thickness (meanIMT) and the plaque score (PS). The prevalences of low (0-22), intermediate (23-32), and high (≥33) SXscore patients were 84.8, 7.4, and 7.8%, respectively. The SXscore was correlated with the meanIMT (Spearmans rank correlation coefficient; ρ = 0.442, P< 0.0001) and the PS (ρ = 0.544; P< 0.0001). The odds ratios associated with the meanIMT and the PS for prediction of an intermediate or the high SXscore were 1.24 and 1.31, respectively. The areas under the receiver-operating characteristic curves for the meanIMT and the PS to predict the intermediate or the high SXscore were 0.791 and 0.846, respectively. When we set the cut-off value of a meanIMT of 0.9 mm, the sensitivity was 92.1% for intermediate or the high SXscore. Similarly, a cut-off level of a PS of 5 presented a sensitivity of 96.1%. A meanIMT ≥0.9 mm and a PS ≥ 5 had negative predictive values of 97.3 and 98.6%, respectively, for intermediate or high SXscore. CONCLUSION Carotid-US parameters have predictive value for the SXscore. In addition, the PS and the meanIMT showed excellent negative predictive value for the presence of complex coronary artery lesions.

A comparative approach of four different image registration techniques for quantitative assessment of coronary artery calcium lesions using intravascular ultrasound

In IVUS imaging, constant linear velocity and a constant angular velocity of 1800 rev/min causes displacement of the calcium in subsequent image frames. To overcome this error in intravascular ultrasound video, IVUS image frames must be registered prior to the lesion quantification. This paper presents a comprehensive comparison of four registration methods, namely: Rigid, Affine, B-Splines and Demons on five set of calcium lesion quantification parameters namely: (i) the mean lesion area, (ii) mean lesion arc, (iii) mean lesion span, (iv) mean lesion length, and (v) mean lesion distance from catheter. Using our IRB approved data of 100 patient volumes, our results shows that all four registrations showed a decrease in five calcium lesion parameters as follows: for Rigid registration, the values were: 4.92%, 5.84%, 5.89%, 5.27%, and 4.57%, respectively, for Affine registration the values were: 6.06%, 6.51%, 7.28%, 6.50%, and 5.94%, respectively, for B-Splines registration the values were: 7.35%, 8.03%, 9.54%, 8.18%, and 7.62%, respectively, and for Demons registration the five parameters were 7.32%, 8.02%, 10.11%, 7.94%, and 8.92% respectively. The relative overlap of identified lesions decreased by 5.91% in case of Rigid registration, 6.23% in case of Affine registration, 4.48% for Demons registration, whereas it increased by 3.05% in case of B-Splines registration. Rigid and Affine transformation-based registration took only 0.1936 and 0.2893 s per frame, respectively. Demons and B-Splines framework took only 0.5705 and 0.9405 s per frame, respectively, which were significantly slower than Rigid and Affine transformation based image registration.

IMPROVED CORRELATION BETWEEN CAROTID AND CORONARY ATHEROSCLEROSIS SYNTAX SCORE USING AUTOMATED ULTRASOUND CAROTID BULB PLAQUE IMT MEASUREMENT

Described here is a detailed novel pilot study on whether the SYNTAX (Synergy between percutaneous coronary intervention with TAXUS and cardiac surgery) score, a measure of coronary artery disease complexity, could be better predicted with carotid intima-media thickness (cIMT) measures using automated IMT all along the common carotid and bulb plaque compared with manual IMT determined by sonographers. Three hundred seventy consecutive patients who underwent carotid ultrasound and coronary angiography were analyzed. SYNTAX score was determined from coronary angiograms by two experienced interventional cardiologists. Unlike most methods of cIMT measurement commonly used by sonographers, our method involves a computerized automated cIMT measurement all along the carotid artery that includes the bulb region and the region proximal to the bulb (under the class of AtheroEdge systems from AtheroPoint, Roseville, CA, USA). In this study, the correlation between automated cIMT that includes bulb plaque and SYNTAX score was found to be 0.467 (p < 0.0001), compared with 0.391 (p < 0.0001) for the correlation between the sonographers IMT reading and SYNTAX score. The correlation between the automated cIMT and the sonographers IMT was 0.882. When compared against the radiologists manual tracings, automated cIMT system performance had a lumen-intima error of 0.007818 ± 0.0071 mm, media-adventitia error of 0.0179 ± 0.0125 mm and automated cIMT error of 0.0099 ± 0.00988 mm. The precision of automated cIMT against the manual radiologists reading was 98.86%. This current automated algorithm revealed a significantly stronger correlation between cIMT and coronary SYNTAX score as compared with the sonographers cIMT measurements with multiple cardiovascular risk factors. We benchmarked our correlation between the automated cIMT that includes bulb plaque and SYNTAX score against a previously published (Ikeda et al. 2013) AtheroEdgeLink (AtheroPoint) correlation between the automated cIMT that does not include bulb plaque and SYNTAX score and had an improvement of 44.58%. By sampling cIMT in the bulb region, the automated cIMT technique improves the degree of correlation between coronary artery disease lesion complexity and carotid atherosclerosis characteristics.

Shape-Based Approach for Coronary Calcium Lesion Volume Measurement on Intravascular Ultrasound Imaging and Its Association With Carotid Intima-Media Thickness

Coronary calcification plays an important role in diagnostic classification of lesion subsets. According to histopathologic studies, vulnerable atherosclerotic plaque contains calcified deposits, and there can be considerable variation in the extent and degree of calcification. Intravascular ultrasound (IVUS) has demonstrated its role in imaging coronary arteries, thereby displaying calcium lesions. The aim of this work was to develop a fully automated system for detection, area and volume measurement, and characterization of the largest calcium deposits in coronary arteries. Furthermore, we demonstrate the correlation between the coronary calcium IVUS volume and the neurologic risk biomarker B‐mode carotid intima‐media thickness (IMT).

Association of automated carotid IMT measurement and HbA1c in Japanese patients with coronary artery disease.

AIMS The purpose of this study was to evaluate whether carotid IMT (cIMT) identified using automated software is associated with HbA1c in Japanese patients with coronary artery disease. METHODS 370 consecutive patients (males 218; median age 69 years ± 11) who underwent carotid-US and first coronary angiography were prospectively analyzed. After ultrasonographic examinations were performed, the plaque score (PS) was calculated and automated IMT analysis was obtained with a dedicated algorithm. Pearson correlation analysis was performed to calculate the association between automated IMT, PS and HbA1c. RESULTS The mean value of cIMT was 1.00 ± 0.47 mm for the right carotid and 1.04 ± 0.49 mm for the left carotid; the average bilateral value was 1.02 ± 0.43 mm. No significant difference of cIMT was detected between men and women. We found a direct correlation between cIMT values and HbA1c (p=0.0007) whereas the plaque score did not correlate with the HbA1c values (p>0.05) CONCLUSION: The results of our study confirm that automated cIMT values and levels of HbA1c in Japanese patients with coronary artery disease are correlated whereas the plaque score does not show a statistically significant correlation.

Impact of Continuous Deterioration of Kidney Function 6 to 8 Months After Percutaneous Coronary Intervention for Acute Coronary Syndrome

Preprocedural chronic kidney disease and contrast-induced acute kidney injury are predictors of in-hospital death and long-term mortality. However, neither the time course of kidney function after percutaneous coronary intervention (PCI) nor the relation between the time course of kidney function and prognosis has been adequately studied. We studied 531 patients who underwent PCI for acute coronary syndrome. The continuous deterioration of kidney function (CDKF) was defined as a >25% increase in serum creatinine level or serum creatinine >0.5 mg/dl above baseline at 6 to 8 months after PCI. CDKF was observed in 87 patients (16.4%). Independent risk factors for CDKF were contrast-induced acute kidney injury, preprocedural hemoglobin level, and proteinuria. Patients with CDKF exhibited significant higher 5-year mortality rate than patients without CDKF (25% vs 9.4%, log-rank p = 0.0006). Independent risk factors for 5-year mortality were age >75 year, anemia, New York Heart Association class III or IV, low ejection fraction, and CDKF. CDKF is associated with an increased risk of all-cause mortality of 5 years in patients with acute coronary syndrome undergoing PCI.

Accurate cloud-based smart IMT measurement, its validation and stroke risk stratification in carotid ultrasound

This study presents AtheroCloud™ - a novel cloud-based smart carotid intima-media thickness (cIMT) measurement tool using B-mode ultrasound for stroke/cardiovascular risk assessment and its stratification. This is an anytime-anywhere clinical tool for routine screening and multi-center clinical trials. In this pilot study, the physician can upload ultrasound scans in one of the following formats (DICOM, JPEG, BMP, PNG, GIF or TIFF) directly into the proprietary cloud of AtheroPoint from the local server of the physicians office. They can then run the intelligent and automated AtheroCloud™ cIMT measurements in point-of-care settings in less than five seconds per image, while saving the vascular reports in the cloud. We statistically benchmark AtheroCloud™ cIMT readings against sonographer (a registered vascular technologist) readings and manual measurements derived from the tracings of the radiologist. One hundred patients (75 M/25 F, mean age: 68±11 years), IRB approved, Toho University, Japan, consisted of Left/Right common carotid artery (CCA) artery (200 ultrasound scans), (Toshiba, Tokyo, Japan) were collected using a 7.5MHz transducer. The measured cIMTs for L/R carotid were as follows (in mm): (i) AtheroCloud™ (0.87±0.20, 0.77±0.20); (ii) sonographer (0.97±0.26, 0.89±0.29) and (iii) manual (0.90±0.20, 0.79±0.20), respectively. The coefficient of correlation (CC) between sonographer and manual for L/R cIMT was 0.74 (P<0.0001) and 0.65 (P<0.0001), while, between AtheroCloud™ and manual was 0.96 (P<0.0001) and 0.97 (P<0.0001), respectively. We observed that 91.15% of the population in AtheroCloud™ had a mean cIMT error less than 0.11mm compared to sonographers 68.31%. The area under curve for receiving operating characteristics was 0.99 for AtheroCloud™ against 0.81 for sonographer. Our Framingham Risk Score stratified the population into three bins as follows: 39% in low-risk, 70.66% in medium-risk and 10.66% in high-risk bins. Statistical tests were performed to demonstrate consistency, reliability and accuracy of the results. The proposed AtheroCloud™ system is completely reliable, automated, fast (3-5 seconds depending upon the image size having an internet speed of 180Mbps), accurate, and an intelligent, web-based clinical tool for multi-center clinical trials and routine telemedicine clinical care.

1,5-Anhydro-D-glucitol predicts coronary artery disease prevalence and complexity.

BACKGROUND The relationship between hemoglobin A1c (HbA1c) levels and coronary artery disease (CAD) has previously been confirmed. Serum 1,5-anhydro-D-glucitol (1,5-AG) levels are a useful clinical marker for short-term glycemic status that reflect glycemic excursions with greater sensitivity compared with HbA1c, specifically in the postprandial state. Postprandial hyperglycemia is an important CAD risk factor. Thus, the aim of this study was to compare HbA1c with 1,5-AG as a CAD predictor. METHODS The subjects consisted of 336 consecutive patients who underwent their first coronary angiography between July 2011 and March 2013. The relationship between CAD prevalence and HbA1c as well as CAD prevalence and 1,5-AG levels was evaluated. The correlation between CAD complexity and HbA1c or 1,5-AG was also assessed. CAD complexity was evaluated by the SYNTAX score. RESULTS CAD patients presented with significantly lower 1,5-AG and higher HbA1c values than patients without CAD (11.6 μg/ml [6.1, 19.1] vs. 17.6 μg/ml [11.9, 25.0], p<0.001, and 6.0% [5.6, 7.1] vs. 5.7% [5.4, 6.2], p<0.001, respectively) (median [25th, 75th percentiles]). According to logistic regression analysis, 1,5-AG was a predictor of CAD prevalence (odds ratio 0.94, 95% confidence interval 0.90-0.97). However, HbA1c levels did not present a predictive value for CAD. Levels of 1,5-AG and HbA1c were significantly correlated with SYNTAX scores (ρ=-0.27, p<0.001; and ρ=0.23, p<0.001, respectively). CONCLUSIONS The use of 1,5-AG, may be superior to HbA1c in predicting CAD prevalence. Both 1,5-AG and HbA1c correlate with CAD complexity.

Carotid inter-adventitial diameter is more strongly related to plaque score than lumen diameter: An automated tool for stroke analysis.

To compare the strength of correlation between automatically measured carotid lumen diameter (LD) and interadventitial diameter (IAD) with plaque score (PS).

PCA-based polling strategy in machine learning framework for coronary artery disease risk assessment in intravascular ultrasound

BACKGROUND AND OBJECTIVE Percutaneous coronary interventional procedures need advance planning prior to stenting or an endarterectomy. Cardiologists use intravascular ultrasound (IVUS) for screening, risk assessment and stratification of coronary artery disease (CAD). We hypothesize that plaque components are vulnerable to rupture due to plaque progression. Currently, there are no standard grayscale IVUS tools for risk assessment of plaque rupture. This paper presents a novel strategy for risk stratification based on plaque morphology embedded with principal component analysis (PCA) for plaque feature dimensionality reduction and dominant feature selection technique. The risk assessment utilizes 56 grayscale coronary features in a machine learning framework while linking information from carotid and coronary plaque burdens due to their common genetic makeup. METHOD This system consists of a machine learning paradigm which uses a support vector machine (SVM) combined with PCA for optimal and dominant coronary artery morphological feature extraction. Carotid artery proven intima-media thickness (cIMT) biomarker is adapted as a gold standard during the training phase of the machine learning system. For the performance evaluation, K-fold cross validation protocol is adapted with 20 trials per fold. For choosing the dominant features out of the 56 grayscale features, a polling strategy of PCA is adapted where the original value of the features is unaltered. Different protocols are designed for establishing the stability and reliability criteria of the coronary risk assessment system (cRAS). RESULTS Using the PCA-based machine learning paradigm and cross-validation protocol, a classification accuracy of 98.43% (AUC 0.98) with K=10 folds using an SVM radial basis function (RBF) kernel was achieved. A reliability index of 97.32% and machine learning stability criteria of 5% were met for the cRAS. CONCLUSIONS This is the first Computer aided design (CADx) system of its kind that is able to demonstrate the ability of coronary risk assessment and stratification while demonstrating a successful design of the machine learning system based on our assumptions.