Satoshi Yamada1, Kaoru Komuro2, Mariko Taniguchi3, Ayumi Uranishi3, Hiroshi Komatsu4, Toshihiko Asanuma3, Fuminobu Ishikura3, Hisao Onozuka4, Taisei Mikami5, Hiroyuki Tsutsui4, Shintaro Beppu3. 1. Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita, Sapporo, 060-8638, Japan. syamada@med.hokudai.ac.jp. 2. Department of Clinical Research, Hakodate National Hospital, Hakodate, Japan. 3. School of Allied Health Sciences, Osaka University Faculty of Medicine, Osaka, Japan. 4. Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita, Sapporo, 060-8638, Japan. 5. Department of Health Sciences, Hokkaido University School of Medicine, Sapporo, Japan.
Abstract
PURPOSE: In high mechanical index (MI) contrast ultrasonography it has been shown that the power of contrast signal intensity (CI) has a strong linear correlation with the concentration of the ultrasound contrast agent under conditions of constant applied acoustic pressure. However, it is unclear whether the linearity is preserved in low-MI contrast ultrasonography. Thus, we investigated the relationship between ultrasound contrast concentration and CI in vitro. METHODS: Solutions of the ultrasound contrast agents Definity and Imagent were prepared at concentrations of 0.5, 2, 8, 32, and 128 μl/l. Placing a jelly block between the transducer and the solution, the solutions were transmitted using pulse subtraction imaging with an MI of 0.05, 0.1, and 0.5. CI was measured in dB in a region of interest 3 mm in height placed just below the border between the jelly and the solution. Data were plotted using double logarithm scales, where the concentration was expressed in dB as 10 × log (concentration). RESULTS: CI in dB had a strong linear correlation with concentration in dB for both agents with any MI. Best fitted slopes were close to 1, indicating that the power of CI is proportional to the concentration. CONCLUSIONS: In low-MI contrast ultrasonography, the power of CI is proportional to contrast concentration, and CI in dB is logarithmic to the concentration. Thus, the microbubble concentration can be quantitatively measured even in low-MI contrast ultrasonography.
PURPOSE: In high mechanical index (MI) contrast ultrasonography it has been shown that the power of contrast signal intensity (CI) has a strong linear correlation with the concentration of the ultrasound contrast agent under conditions of constant applied acoustic pressure. However, it is unclear whether the linearity is preserved in low-MI contrast ultrasonography. Thus, we investigated the relationship between ultrasound contrast concentration and CI in vitro. METHODS: Solutions of the ultrasound contrast agents Definity and Imagent were prepared at concentrations of 0.5, 2, 8, 32, and 128 μl/l. Placing a jelly block between the transducer and the solution, the solutions were transmitted using pulse subtraction imaging with an MI of 0.05, 0.1, and 0.5. CI was measured in dB in a region of interest 3 mm in height placed just below the border between the jelly and the solution. Data were plotted using double logarithm scales, where the concentration was expressed in dB as 10 × log (concentration). RESULTS: CI in dB had a strong linear correlation with concentration in dB for both agents with any MI. Best fitted slopes were close to 1, indicating that the power of CI is proportional to the concentration. CONCLUSIONS: In low-MI contrast ultrasonography, the power of CI is proportional to contrast concentration, and CI in dB is logarithmic to the concentration. Thus, the microbubble concentration can be quantitatively measured even in low-MI contrast ultrasonography.
Authors: Sarah Shimoni; Nikolaos G Frangogiannis; Constadina J Aggeli; Kesavan Shan; Mario S Verani; Miguel A Quinones; Rafael Espada; George V Letsou; Gerald M Lawrie; William L Winters; Michael J Reardon; William A Zoghbi Journal: Circulation Date: 2003-02-04 Impact factor: 29.690