Breastnet uses an ultrasound to guide a a core needle to biopsy breast. Before the biopsy procedure. A Breastnet technologist will first use a local anesthetic to numb the area. Then the technologist will hold the ultrasound device against your breast to see the area. The ultrasound images help the technologist guide the biopsy device to the suspicious area. The technologist will remove a sample of tissue with the needle in the device.