Accuracy, Reproducibility, and Comparability of Doppler Tissue Imaging by Two High-end Ultrasound Systems Jesper Kjaergaard, MD, Josef Korinek, MD, Marek Belohlavek, MD, PhD, Jae K. Oh, MD, Peter Sogaard, MD, DMSc, and Christian Hassager, MD, DMSc, Rochester, Minnesota, and Copenhagen, Denmark Introduction: Doppler tissue imaging is a new tech- nology for quantitative evaluation of myocardial motion and contractility, and is available in several ultrasound systems. This study evaluates the compa- rability, accuracy, and reproducibility of measure- ments of velocity, strain rate, and strain by two high-end ultrasound systems. Methods: Accuracy was assessed by imaging a tis- sue-mimicking gelatin phantom, and the compara- bility of measurements in the right ventricular free wall and interventricular septum was assessed in 20 healthy participants. Reproducibility was evaluated by repeated recordings in vitro and in a random subset of patients. Results: In vitro, a high degree of accuracy was found in both systems, with one system measuring slightly lower values than the reference values (mean differ- ence 0.35  0.18 cm/s, P < .001). Values higher than the reference values were measured by both systems for strain and strain rate. In vivo, no systematic differ- ences in measured velocities, strain rate, and strain were found; however, wide limits of agreement were seen for strain and strain rate. Measurements of tissue velocity, strain, and strain rate were well reproducible, nevertheless wide variation was found in both systems (coefficient of variation  9%-19%). Conclusion: For clinical purposes, both systems have sufficient accuracy for measurements of tissue velocity. The variation in measurements of strain rate and strain by Doppler tissue imaging should be taken into account when designing studies using this new technology. Approaches to potentially re- duce this variation should be addressed in future studies. (J Am Soc Echocardiogr 2006;19:322-328.) Doppler tissue imaging (DTI) and the derived parameters of strain rate and strain are increasingly used in echocardiographic research. Several manu- facturers of ultrasound equipment have imple- mented the DTI technology in their high-end ultra- sound systems. However, comparison of DTI velocity measurements from different systems has been reported only rarely. 1 No information is avail- able on the accuracy and precision of strain rates and strains from different systems. Previously, several studies have validated Doppler tissue velocity measurements, predominantly using pulsed wave DTI measurements, and almost exclu- sively in measurements of the left ventricle (LV). As DTI of the right ventricle (RV) has gained more attention in recent years, 2-4 information on the accu- racy and comparability of measurements of RV func- tion is needed. Some studies suggest that reproducibil- ity of tissue velocity measurements in the RV is equal to or lower than the LV, whereas the reproducibility of RV strain rates and strains has not been assessed. 5,6 However, reproducibility of measurements is of- ten tested in DTI studies on the same recordings, whereas a more clinically relevant strategy would be analysis of repeated recordings. 5 The aim of our study was to evaluate and compare the accuracy, comparability, and reproducibility of Doppler tissue velocity, strain rate, and strain in vivo in the LV and RV in selected healthy participants and in vitro using a tissue-mimicking phantom with two different high-end ultrasound systems. METHODS Echocardiography Imaging was done with Vivid 7 Vantage (GE Vingmed, Horten, Norway) equipped with an M3S transducer and Sonos 7500 (Philips, Bothell, Wash) with an S3 transducer. Corresponding software (EchoPac for PC, Version 3.1, GE From the Mayo Clinic College of Medicine, Rochester, Minnesota (J.Kj., J.K., M.B., J.K.O.); and the Departments of Cardiology at Copenhagen University Hospital Rigshospitalet (J.Kj., C.H.) and Copenhagen University Hospital Gentofte (P.S.). Supported in part by the Danish Heart Foundation grant No. 03-2-3-46A-22112 (research fellowship to Dr Kjaergaard) and by the National Institutes of Health grant HL68555 (Dr Belohlavek). Reprint requests: Jesper Kjærgaard, MD, Department of Cardiology B 2141, University Hospital of Copenhagen, Rigshospitalet, 2100 Copenhagen Ø, Denmark (E-mail: jesper.kjaergaard@dadlnet.dk). 0894-7317/$32.00 Copyright 2006 by the American Society of Echocardiography. doi:10.1016/j.echo.2005.10.007 322