The technology reflects radio signals from the patient and uses an algorithm to track the implant. The biggest challenge is simply determining the difference between reflections from the skin and the implant itself. To do this, the CSAIL team uses a diode to create combinations of signals that help filter out skin reflections. According to MIT, it is able to work "to the centimeter" and the implant does not have to send its own signal.
There is still much to do. MIT aims to increase accuracy by combining ReMix with data such as MRI scans, and recognizes that the algorithm may require changes to accommodate the wide variety of human bodies. However, the applications are already clear. Doctors could use less invasive implantation methods while confirming that they are achieving the goal. This could allow implants in several circumstances. For example, proton-based cancer therapy could use trackable markers to ensure that the tumor stays in place (necessary to explode it with protons) and improve the quality of treatment.