Quantitative ultrasound microscopy imaging of cells

Using high-frequency ultrasound, two approaches were used to quantify eukaryotic cell properties. One approach (10-100 MHz) is model-based wherein live cells of known number and volume density are placed in a mixture of bovine plasma and thrombin to form a clot. Backscatter coefficient estimates are modeled against a concentric sphere scattering model to yield cell and nucleus diameters as well as density and speed of cytoplasm and nucleus of Chinese hamster ovary (CHO) and 3T3 fibroblast cells. Estimated cell and nucleus diameters were consistent with direct light microscope measures [CHO cell: 13 microns, nucleus: 6.6 microns and 3T3 cell: 23 microns, nucleus: 13 microns]. For CHO cells, both density and speed of the cytoplasm were less than those of the nucleus. For the 3T3 cells, both density and speed of the cytoplasm were not significantly different from those of the nucleus. The other approach (65-170 MHz) is a direct through-transmission round-trip measure (RF echo reflected from strong reflector), yielding estimates of attenuation and speed of cytoplasm and nucleus of MAT B III mammary adenocarcinoma cell. Speed of cytoplasm was not significantly different from that of the nucleus. The attenuation of the cytoplasm and nucleus were 0.61-0.77 and 0.94 dB/cm-MHz, respectively. [Supported by NIH R01CA111289; l'Ecole Centrale de Lille for TA; Canadian National Science and Engineering Research Council for LAW]