Calculus detection for ultrasonography using decorrelation of forward scattered wave

Purpose The purpose of this paper is to propose a novel strategy to detect small calculi efficiently. Methods The proposed calculus detection strategy focuses on decorrelation of forward scattered waves caused by the failure of Born's approximation. A calculus causes waveform changes of transmit pulses, resulting in a decrease in the cross-correlation coefficients calculated from IQ signals scattered near the calculus position. Therefore, we can detect calculi from the appearance of dips in correlation coefficients. Results When a calculus exists in a digital tissue map, sharp and deep dips in cross-correlation coefficients between acoustic IQ signals appear around the calculus. By contrast, no apparent dip exists when a tissue map contains no calculus. A scan line interval of 0.2 mm or less is appropriate for the conditions simulated in this paper, and the proper transmit focal range for the proposed method is at a calculus range. Conclusion These results imply that the proposed strategy can improve the efficiency of US devices for small calculus detection.