We present a lifetime fluorescence imaging system for small animal imaging. The system uses a linear fiber array with given separations between a single source fiber and several detection fibers. The general goal is to detect and localize tumors, using specific fluorescent markers and investigate their progression. We investigated applications of the developed system to mouse imaging, using as contrast agent Alexa Fluor 750 conjugated to tumor specific antibodies (Herceptin). Realized 2D mapping of fluorescence lifetime indicate lower lifetime value in the tumor area.