A system and method for molecular breast imaging (MBI) provides enhanced tumor analysis and, optionally, a real-time biopsy guidance. The system includes a detector head including a gamma ray detector and a multisegment collimator in a collimator frame. The collimator contains multiple collimation sections that have respectively different collimating characteristic and that are individually repositionable with respect to the detector. An image of the tissue acquired with the system may include spatially separate image portions containing image information about the same portion of the imaged tissue. A system of mounting the multisegment collimator in the detector head includes a collimator tray that is laterally moveable within the frame and/or slidable in and out of the frame.
