Before each MBI scan, you will receive an injection of 99mTc sestamibi (a type of drug that gives off energy that is seen with special cameras, like a mammogram). You will have an MBI scan about 5 minutes after you receive Tc99m sestamibi. During the scan, your breast will be positioned between 2 detectors and lightly compressed. The detectors are 2 square cameras, which look very similar to mammogram cameras. You are seated during the entire procedure and the scan should take about an hour.