20 Echocardiography is a well-established clinical tool for the noninvasive assessment of regional and global left ventricular (LV) function in children. 1 In pediatric cardiology, quantification of myocardial function is usually based on either visual interpretation of radial endocardial excursion derived from 2-dimensional (2D) ultrasound or on conventional M-mode echocardiographic indices of either radial thicken- ing/thinning or long-axis atrioventricular ring dis- placement.However,the visual interpretation of radi- al function by endocardial excursion or myocardial thickening, is nonquantitative and has shown to be both subjective and experience dependent. 2 Measurement of regional radial function by con- ventional M-mode techniques is only applicable to the few LV segments insonated at 90 degrees from the parasternal approach. For long-axis function, the conventional M-mode measurement of long-axis ring excursion only quantifies the overall shortening or lengthening of the subtended myocardial wall and From the Departments of Cardiology and Pediatric Cardiology (B.E., L.M., M.G.,), University Hospital Gasthuisberg, Leuven. Supported by a grant from the Belgian Foundation for Research in Pediatric Cardiology and by a grant from the Foundation for Scientific Research (FWO Levenslijn grant 7.0024.98). Reprint requests: Prof George R. Sutherland, Department of Cardi- ology, University Hospital Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium. (E-mail: George.Sutherland@uz.kuleuven.ac.be). Copyright © 2002 by the American Society of Echocardiography. 0894-7317/2002/$35.00 + 0 27/1/116532 doi:10.1067/mje.2002.116532 Background: Noninvasive assessment of left (LV) and right (RV) ventricular function in children could benefit from a technique that would characterize local myocardial deformation. Color Doppler myo- cardial imaging (CDMI) allows the calculation of either local longitudinal or radial Strain Rate (SR) and Strain (ε). To determine the clinical feasibility and reproducibility of longitudinal and radial SR and ε, the following study was carried out. Methods: CDMI data were obtained from 33 healthy children (4-16 years). To quantify regional longitu- dinal and radial function SR and ε data were ob- tained from apical and parasternal views respec- tively. From the extracted SR curves, peak values for systole, early diastole, and late diastole were calcu- lated. From the extracted ε curves the systolic, early and late diastolic ε values were calculated. Results: LV longitudinal deformation were homoge- neous for LV basal, mid and apical segments (peak systolic SR: –1.9 ± 0.7 s –1 , systolic ε –25% ± 7%). Longitudinal SR and ε values were significantly higher and heterogeneous in the RV (compared with LV walls) and were maximal in the mid part of the RV free wall (peak systolic SR: –2.8 ± 0.7 s –1 , systolic ε –45% ± 13%). The RV inferior wall showed homoge- nous but lower longitudinal SR and ε values. The LV systolic and diastolic SR and ε values were higher for deformation in the radial direction compared with the longitudinal direction (radial peak systolic SR: 3.7 ± 0.9 s –1 , radial systolic ε 57% ± 11%; P < .0001). The interobserver variability for radial systolic ε and SR was 10.3% and 13.1%, respectively. Conclusion: Ultrasound-based Strain SR/ε imaging is a practical, reproducible clinical technique, which allows the calculation of regional longitudinal and radial deformation from both LV and RV segments. The combination of regional SR/ε indices and the timing of specific systolic or diastolic regional events may offer a new noninvasive approach to quantifying regional myocardial function in con- genital and acquired heart disease in children. (J Am Soc Echocardiogr 2002;15:20-8.) Quantification of Regional Left and Right Ventricular Radial and Longitudinal Function in Healthy Children Using Ultrasound-Based Strain Rate and Strain Imaging Frank Weidemann, MD, Benedicte Eyskens, MD, Fadi Jamal, MD, Luc Mertens, MD, PhD, Miroslaw Kowalski, MD, Jan D’Hooge, PhD, Bart Bijnens, PhD, Marc Gewillig, FESC, Frank Rademakers, MD, PhD, Liv Hatle, FESC, and George R. Sutherland, FESC, Leuven, Belgium