I assume that you are concerned that one or both of your implants has a leak. If they are saline implants, you don't need any kind of test. The implants will simply lose volume and you should see a volume difference between your breasts within a matter of days. Cohesive silicone gel implants are harder to evaluate as they hold their shape in the event of a rupture. I still think the first line of detection is a good physical examination of the implants in the office. An MRI is probably the best test for a ruptured silicone gel implant, however, MRI's are expensive and not 100% accurate - another reason why I would suggest scheduling an appointment with a board-certified plastic surgeon first.