Online Journal
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Journal of Medical Ultrasonics

にて英文誌のFull textを閲覧することができます.


1992 - Vol.19

Vol.19 No.09

Original Article(原著)

(0633 - 0639)


Relation between Sound Speed and Density of Rat Livers Measured by Non-Deformable Technique Based on Frequency-Time Analysis of Pulse Response

蜂屋 弘之, 今田 直樹, 大槻 茂雄, 田中 元直

Hiroyuki HACHIYA, Naoki IMADA, Shigeo OHTSUKI, Motonao TANAKA


Precision and Intelligence Laboratory, Tokyo Institute of Technology

キーワード : Tissue characterization, Non-deformable measurement, Sound speed, Rat liver, Frequency-time analysis

Sound speed is an important acoustic parameter for quantitative characterization of living tissues. In this paper, relation between measuring sound speed and density of rat liver tissues are presented. Male Wister rats weighting 200-600 g were used in this experiments. The sound speed was measured by the non-deformable technique based on frequency-time analysis of the pulse response. This method does not require physical contact of ultrasonic probes with living or freshly excised tissue specimens and travel times are estimated using frequency-time analysis of the pulse response to avoid sensitivity to waveform distortion due to tissue inhomogeneity and surface roughness. The rats were divided into a group with 13 normal rats and another group with 6 rats given CCl4 (0.1 ml/kg)twice a week for 6∼8 weeks by intramuscular injection. In the group given CCl4, tap water in which phenobarbitone was dissolved at a concentration of 0.5 g/l was the only drinking water available to the rats. The sound speed was measured for 25 points by scanning a 2×2 mm area 0.5 mm intervals. Measurement was performed in 0.9% saline at 37.0±0.2°C of the bath (coupling) medium. The sound speed and the density in 13 normal livers were 1608.3±2.1 m/s and 1.082±0.002 g/cm3. The sound speed and the density in normal livers are very stable and had no relation to body weight and age. In liver tissues of rats given CCl4 for 6 and 7 weeks, the sound speeds (the density)were 1592.7±2.0 m/s(1.072 g/cm3) and 1584.3±1.9 m/s (1.068 g/cm3) respectively. In liver tissues of 4 rats given CCl4 for 8 weeks, the values were 1573.3±4.3 m/s and 1.064±0.002 g/cm3, respectively. From the microscopic image of HE stained liver tissues, these rat livers were considered to be fatty liver. It was found that the sound speed and the density in rat liver tissues decrease with the progress of fatty liver.