Evaluation of the morphological parameters of cancer cells using high-frequency ultrasound and photoacoustics

A method for acquiring commonly used histological parameters from cultured cancer cells is presented. Morphological features of the HT-29 colorectal cancer, and the MCF-7 breast cancer cell lines were obtained using a hybrid ultra-high frequency acoustic/photoacoustic microscope. The radii of the cell and nucleus were measured and used to calculate the cell nucleus-to-cytoplasm (N:C) ratio. To determine the radius of the cell, ultrasound waves backscattered from the cell were fit to analytical solutions describing acoustic scattering from a fluid sphere. Cells were stained with DRAQ5, a dye that binds to DNA, to facilitate generation of photoacoustic signals from the cell nuclei. Photoacoustic signals measured from the nuclei were fit to analytical solutions to determine the nuclear radius. For the HT-29 cells, the mean nuclear and cell radii were 5.3 ± 1.1 μm and 7.0 ± 0.8 μm, respectively. For the MCF-7 cell line, the mean nucleus and cell radii were found to be 6.0 ± 0.7 μm and 7.7 ± 0.9 μm, respectively. The mean calculated N:C ratio for the HT-29 cells was 2.3 ± 1.9, and the mean N:C ratio for the MCF-7 cells was 1.9±1.0.