Intraoperative tumor detection has been used in many applications, and today the sentinel node technique is a widely employed surgical procedure in breast cancer. Different detector systems are employed but several problems have been reported in clinical practice, in particular the difficulty to accurately detect the sentinel node within the axillary soft tissue. The problem is even greater for abdominal and thoracic tumors. We propose an innovative Imaging Probe (IP) able to visualize on a monitor the primary tumor and secondary lesions, if appropriately radiolabeled. The IP can be optimally applied for minimally invasive surgery in breast cancer treatment, and a preliminary experience related to 15 patients and 20 sentinel nodes is reported here. We compared the results obtained with the IP to those obtained with an Anger camera and a traditional scintillation detector, and found them to be very promising. In particular the surgeon's work is greatly facilitated by direct visual guidance instead of a generic acoustic signal.