Ultra-high frequency acoustic impedance imaging of cancer cells

Acoustic impedance maps of cells can be used to gain insight into its microstructures and physiological state. Information about the cell’s microstructures can be acquired from the acoustic impedance map fluctuations. The maps can also help identify the dominant scattering source in cells. Furthermore, the cell’s physiological state can be inferred from the average acoustic impedance values as many physiological changes in the cell are linked to the alteration in the mechanical properties. A method called acoustic impedance imaging has been used to measure the impedance of biological tissues. We used an acoustic microscope attached to a transducer with a center frequency of 375MHz to acquire acoustic impedance images of breast cancer cells. The generated images suggest that the nucleus has an acoustic impedance similar to the surrounding cytoplasm. Fluorescence and confocal microscopy were used to correlate acoustic impedance images with the cell microstructure (the nucleus). Simulation results demonstrate the system’s capability in detecting cell microstructures close to the substrate. The average acoustic impedance were used to differentiate between single-live, clustered-live and clustered-fixed cancer cells with a measured values of 1.60±0.01 MRayl, 1.61±0.02 MRayl and 1.55±0.02 MRayl respectively.