We present a cell cycle analysis that aims towards improving our previous work by adding another channel and using one more dimension. The data we use is a set of 3D images of mouse cells captured with a spinning disk confocal microscope. All images are available in two channels showing the chromocenters and the fluorescently marked protein PCNA, respectively. In the present paper, we will describe our recent colocalization study in which we use Hessian-based blob detectors in combination with radial features to measure the degree of overlap between both channels. We show that colocalization performed in such a way provides additional discriminative power and allows us to distinguish between phases that we were not able to distinguish with a single 2D channel. © 2010 IEEE.