In vivo variability in quantitative coronary ultrasound and tissue characterization measurements with mechanical and phased-array catheters

Both mechanical and phased-array catheters are used in clinical trials to assess quantitative parameters. Only limited evaluation of the in vivo agreement of volumetrical measurements between such systems has been performed, despite the fact that such information is essential for the conduction of atherosclerosis regression trials. We prospectively evaluated the agreement in morphometric measurements and intravascular ultrasound (IVUS)-based plaque characterization between a 40 MHz rotating transducer (3.2 F Atlantis, Boston Scientific Corp.) and a 20 MHz phased-array catheter (2.9 F Eagle Eye, Volcano Therapeutics, Rancho Cordova, California) in 16 patients. Lumen (7.3+/-2.0 mm(2) vs. 6.7+/-1.8 mm(2), p=0.001) and vessel (11.8+/-3.3 mm(2) vs. 11.0+/-2.9 mm(2), p=0.02) cross-sectional areas (CSA) were significantly greater with the 20 MHz system. Plaque CSA measurements showed no significant difference between systems (4.4+/-2.3 mm(2) vs. 4.4+/-2.1). The relative differences were less than 10% for the three variables. On IVUS-based tissue characterization (13 patients), calculated percentage hypoechogenic volume was significantly higher for the 20 MHz system (96.7+/-2.38 vs. 88.4+/-5.53, p