The fluid and elastic nature of nucleated cells: Implications from the cellular backscatter response

Abstract

In a previous experiment [Baddour et al., J. Acoust. Soc. Am. 117(2), 934–943 (2005)] it was shown that it is possible to deduce the ultrasound backscatter transfer function from single, subresolution cells in vitro, across a broad, continuous range of frequencies. Additional measurements have been performed at high frequencies (10–65MHz) on cells with different relative nucleus sizes. It was found that for cells with a nucleus to cell volume ratio of 0.50, the backscatter response was better modeled as an elastic sphere. For the cells in which the ratio was 0.33, the backscatter showed good agreement with the theoretical solution for a fluid sphere.

Ultrasonic differentiation of normal versus malignant breast epithelial cells in monolayer cultures

“…3 Both packed (centrifuged) cells and dilute cell suspensions have additionally been studied with hf ultrasound to explore the basic scattering properties of normal and cancerous cells and to detect apoptosis in malignant cells in vitro. [4][5][6][7] The sensitivity of 40-MHz ultrasonic backscatter to apoptosis in malignant cells has also been demonstrated in rat tissues ex vivo and in vivo. 8 This work was recently extended to study apoptosis in mouse tumors following photodynamic and radiation therapies.…”

Temperature dependent ultrasonic characterization of biological media

“…Damianou et al, 1 observed temperature dependence of attenuation in dog muscle, liver and kidney over a temperature range from room temperature to 70 C. Other investigators measured the variation of speed of sound and attenuation slope in canine liver samples for a temperature range of 22 C to 95 C (Ref.…”

A study of high frequency ultrasound scattering from non-nucleated biological specimens

“…A recent study by the same group showed that for prostate carci-noma (PC-3) cells whose nucleus to cell volume ratio is 0.33, the backscatter response could be modeled as a fluid sphere. 8 However, the same study found that for human acute myeloid leukemia (OCI-AML-5) cells whose nucleus to cell volume ratio equals to 0.50, the backscatter response was not modeled as well by a fluid sphere. Baddour et al hypothesized that the cytoplasm is of fluid nature whereas the nucleus possesses elastic properties, giving rise to this discrepancy.…”

“…Previous studies of scattering from individual cells 7,8 focused on the analysis of experimental results in the frequency domain through the BSTF. The analysis of data in time domain provides additional insight into scattering behavior of objects, such as ringing patterns and ring-down time.…”

“…Baddour et al hypothesized that the cytoplasm is of fluid nature whereas the nucleus possesses elastic properties, giving rise to this discrepancy. 8 This work attempts to model the ultrasound backscatter ͑10-62 MHz͒ from some non-nucleated biological specimens through the measurement and comparison of the backscatter response from sea urchin oocytes to theoretical predictions from a fluid sphere.…”