Work in progress: ultrasonic texture of normal rat liver tissue using a standardized in vivo measurement

A prototype computer-augmented diagnostic ultrasound system was used in an investigation of the range of echo amplitudes obtained from measurements of normal exteriorized rat livers. A secondary goal was to develop a method for minimizing variations in measurement techniques and instrument stability. The average echo amplitude was obtained from a user-selected homogeneous region of the liver on a B-mode scan image. A similar B-mode scan of a commercially available liver tissue equivalent phantom was also obtained immediately after each rat liver measurement and was used as a calibration scan. A normalization factor developed from the calibration scan was used to correct all in vivo measurements for system variation. The average echo amplitude from the livers of a group of normal rats, when corrected by the calibration scan, exhibited a narrow range of values with a coefficient of variation of only 5%. The development of a technique that yields a narrow range of values for normal tissues should encourage further investigation of tissue characterization methods.