Patients enrolled in this study will receive standard lymphoscintigraphy in nuclear medicine; however, these images will not be reviewed by the investigator until the preoperative mobile gamma camera(MGC)images have been obtained. Upon completion of the preoperative MGC imaging, the investigator will define the location of SLNs and the plan for the surgical approach. The investigator will then review the FGC images and assess the agreement of these two imaging methodologies. The hand-held gamma probe will be used to further evaluate the patient at this time and a final determination of true hot spots will be made based on the information and the clinical judgment of the operating surgeon. The final surgical plan will be decided. The primary data to be obtained from this cohort will be confirmation of the use of MGC imaging as a screening device to identify all nodal basins containing SLNs.