ORIGINAL ARTICLES Ultrasonic Integrated Backscatter Two-dimensional Imaging: Evaluation of M-Mode Guided Acquisition and Immediate Analysis in 55 Consecutive Patients James F. Loomis, Jr., MD, Alan D. Waggoner, BA, RDMS, Kenneth B. Schechtman, PhD, James G. Miller, PhD, Burton E. Sobel, MD, and Julio E. Perez, MD, St. Louis, Mo. We have shown previously that cardiac cycle-dependent integrated backscatter characterizes the physical state of myocardium in patients with ischemic heart disease and cardiomyopathy. In the present study the clinical applicability of M-mode guided two-dimensional integrated backscatter imaging was defined in evaluation of 55 nonselected patients. The mean amplitude of cyclic variation of integrated backscatter in normal segments (long-axis view) was as follows: basal septum, 4.2 ± 1.3 dB (mean ± SD; n = 27), mid-septum, 4.5 ± l.O dB (n = 26), basal posterior, 4.8 ± l.O dB (n = 30), and mid-posterior, 4.8 ± 1.2 decibels (n = 27). The respective mean delay values (R wave to nadir) were as follows: 0.89 ± 0.09, 0.84 ± 0.09, 0.86 ± 0.09, and 0.85 ± 0.12. At least one cardiac cycle could be analyzed fully in 62% of patients. Limitations included technically difficult two-dimensional echocardiography, inadequate M-line orientation, technically remediable errors, or poor quality integrated backscatter images. In abnormal segments (n = 13) cyclic variation was reduced and delay was prolonged (1.2 ± 1.1 dB and 1.21 ± 1.1, respectively). Intraobserver and interobserver variability for amplitude measurements were modest, with respective correlation coefficients of r = 0.93; r = 0.72. The findings demonstrate that M-mode-assisted integrated backscatter is a practical approach for characterization of regional myocardial properties promptly and at the bedside in a large portion of patients with cardiac disease. ( J AM Soc EcHo 1990;3 :255-65.) Ultrasonic tissue characterization is an attractive adjunce· 14 to conventional echocardiography for the evaluation of the physical state of myocardium and detection of functional derangements associated with ischemic or myopathic states. We have previously shown that tissue characterization and quantification of cardiac cycle-dependent cyclic variation of ultra- sonic integrated backscatter provide criteria indica- tive of the physical properties of myocardium in se- lected patients with abnormal septal motion 15 and in selected patients with cardiomyopathy 16 or ischemic heart disease. 17 • 18 The prototype approach used in previously reported studies required extensive and time-consuming off-line computer-assisted analysis of the real time acquired integrated backscatter im- ages to derive the magnitude of cyclic variation of integrated backscatter and its delay (R wave to nadir of cyclic variation of integrated backscatter, corrected by the QT interval). From the Cardiovascular Division, Cardiac Diagnostic Labora- tory, Biomedical Computer Laboratory, and the Department of Physics, Washington University Medical Center. Supported in part by National Instimtes of Health grants HL- 17646 (SCOR in Ischemic Heart Disease), ROl-HL-39063, and ROl-HL-40302. Reprint requests: Julio E. Perez, MD, Cardiovascular Division, Box 8086, Washington University School of Medicine, 660 South Euclid Ave., St. Louis, MO 63110. 27/l/18947 In the present study we sought to define the clinical applicability of a less labor-intensive, more rapidly facilitated M-mode guided approach to obtain im- mediate on-line assessment of quantitative segmental tissue acoustic properties in unselected consecutive 255