Thanks. This is very interesting. The goal of identifying and characterizing circulating tumor cells has been a consistent interest in cancer research. Prior to this, a microfluidics-based method called "flow cytometry" has been used, in which the cells of interest are tagged with one or more fluorescent antibodies against some "unique" proteins or sugars on the surface of the cancer cells, and then the cells are run very fast in single file through a laser beam and an optical bench full of filters and photomultiplier tubes. Data on fluorescence level for each fluorophore, size and refractility (scatter) are collected on each cell. No image, just a histogram.