High-resolution sonography of fish organs and tissues at early stages of development

Abstract

This paper examines the use of high-resolution sonography for non-invasive examination of fish at early stages of development. Using a pulsed high-frequency ultrasound scanner operating in pulse-echo mode, it is possible to achieve longitudinal and transverse resolution sufficient for visualizing fish specimens at the embryonic and larval stages of development. In this device, the organism being studied is placed in an immersion cell filled with natural water, enabling non-invasive in vivo examination. The resulting sonographic images differ significantly from optical ones, as ultrasound responses depend on the spatial distribution of the elastic-viscous, rather than optical, properties of the object. Sonography enables long-term observation of organism development at the embryonic stage, and the use of time-lapse imaging allows for visualization of blastodisc division, blastomere formation and division, blastula formation, cell layer movement, and the development of embryonic organs. The high repetition rate of ultrasound pulses (up to 10 kHz) enables the recording of rapid processes in the body, such as heartbeats and blood flow. Digital processing, performed through two-dimensional autocorrelation analysis of the recorded ultrasound spatiotemporal data, allows for the visualization of blood flow and the calculation of the vertical component of blood velocity depending on the phase of the cardiac cycle. Analysis of the characteristics of sonographically determined spatiotemporal blood velocity distributions allows for the assessment of the body's functional state and the study of the impact of external factors.

Speaker

Sergey Titov
Scientific and Technological Centre of Unique Instrumentation of the Russian Academy of Sciences
Russia

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