Abstract: The methods described in this invention are used to analyze images of circulating tumor cells (CTC). Images are acquired from a number of platforms, including multiparameter flow cytometry, the CellSporter fluorescent microscopy imaging system and CellTracks Analyzer. These images are then ranked based on various properties and are presented to the user in order of most likely to least likely positive CTC events. The ranking method is useful to diagnose, monitor, and screen disease based on circulating rare cells, such as malignancy as determined by CTC.