2. after completion of the sentinel node biopsy procedure In each of these assessments, the following will be recorded: the number and location of sentinel nodes, the correspondence with preoperative hot spots determined by the clinical gamma detection devices (fixed camera, MGC and hand-held probe), the time required for imaging, and technical features of use, advantages, and limitations of the MGC imaging system. The individual sentinel nodes will be imaged ex vivo and counted with the hand-held probe.