Non - Invasive Evaluation of Atherosclerotic Plaque Composition: Comparison Between the Reference Analyzer and A New Gray Scale Median Color-Mapping Software

Introduction: The non-invasive analysis of plaque echolucency (ECL) with Adobe Photoshop® has proven to reduce the subjectivity of ultrasonic evaluation of atherosclerosis. However, ECL provides information concerning only one of the aspects that contribute to vulnerability (plaque echodensity). Hemodyn 4m® is a grey scale median (GSM) plaque analyzer to asses distribution of areas with different tissue composition within atherosclerotic plaques, based in a color mapping process. AIM: To evaluate the correlation and concordance of a new GSM and color mapping plaque analyzer, Hemodyn 4m®, with the current reference method, Adobe Photoshop®. Methods: Evaluation of fifty carotid atherosclerotic plaques (miointima thickness above 1.2mm) obtained with a 10 MHZ linear array transducer (Vivid Five®, G. E. Corp.) from 50 consecutive patients. Correlation analysis was done with Spearman test; concordance, intraobserver and interobserver analysis with Bland and Altmann method. Results: Hemodyn 4m® show excellent correlation (GSM, r2: 0.84, p< 0.001) and concordance with Adobe Photoshop® (difference of Hemodyn 4m® compared to Adobe® Photoshop, - 1.9 units of the GSM average values, 2SD ±17.8; n=50), with low intraobserver (Difference Hemodyn 4 m®, 1 units of values of grey scale average median, SD±15.8; n=25) and interobserver variability (Difference with Hemodyn 4 m®, 0.4 units of values of GSM average, SD±16.8; n=25). Conclusion: Adobe Photoshop® and Hemodyn 4m® are equivalent methods for GSM analysis of the ECL plaque evaluation. Hemodyn 4m® provides a more accurate visual characterization and location of the different tissue components of atherosclerotic plaques.