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© 2007 by the American Institute of Ultrasound in Medicine
J Ultrasound Med 26:739-748 • 0278-4297

Parametric Detection and Measurement of Perfusion Defects in Attenuated Contrast Echocardiographic Images

Shiro Yoshifuku, MD, Shigao Chen, PhD, Eileen McMahon, PhD, Josef Korinek, MD, Akiko Yoshikawa, MD, Izuru Ochiai, MD, Partho P. Sengupta, MBBS, MD, DM and Marek Belohlavek, MD, PhD

Departments of Internal Medicine (S.Y., J.K., A.Y., I.O., P.P.S.) and Physiology and Biomedical Engineering (S.C.), Mayo Clinic College of Medicine, Rochester, Minnesota USA; and Department of Internal Medicine, Mayo Clinic College of Medicine, Scottsdale, Arizona USA (E.M., M.B.).

Address correspondence to Marek Belohlavek, MD, PhD, Mayo Clinic Arizona, 13400 E Shea Blvd, Scottsdale, AZ 85259 USA. E-mail: belohlavek.marek{at}mayo.edu

Objective. Attenuation of radio frequency (RF) signals limits the use of contrast echocardiography. The harmonic-to-fundamental ratio (HFR) of the RF signals compensates for attenuation. We tested whether HFR analysis measures the left ventricular nonperfused area under simulated experimental attenuation. Methods. Radio frequency image data from short axis systolic projections were obtained from 11 open-chest dogs with left anterior descending or left circumflex coronary artery occlusion followed by left atrial bolus injection of a perflutren microbubble contrast agent. Clinical attenuation was simulated by calibrated silicone pads interposed between the epicardial surface and the transducer to induce mild (7-dB) and severe (14-dB) reduction of the backscattered RF signals. Harmonic-to-fundamental ratio values were calculated for each image pixel for 0-, 7-, and 14-dB attenuation conditions and reproducibly showed a "perfused area" and a "nonperfused area." A reference nonperfused area was obtained by manual delineation in high-quality contrast scans. Results. Correlations of the HFR-detected and manually outlined perfusion defect areas were R = 0.92 for 0 dB, R = 0.94 for 7 dB, and R = 0.90 for 14 dB; the mean difference was less than 0.36 cm2 (negligible) in all 3 attenuation settings. Conclusions. Attenuation compensation by our HFR method allows precise measurement of myocardial perfusion defect areas in contrast scans with simulated high level of attenuation.

Key Words: contrast echocardiography • harmonic ultrasound • myocardial perfusion • radio frequency signal • ultrasound attenuation

Abbreviations: HFR, harmonic-to-fundamental ratio • LAD, left anterior descending coronary artery • LCX, left circumflex coronary artery • LV, left ventricular • MI, mechanical index • RF, radio frequency

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Copyright © 2007 by the American Institute of Ultrasound in Medicine.