A method for providing power management in a radio frequency power amplifier using adaptive envelope tracking is provided that includes receiving an input voltage. The techniques may include selecting a rasterization mode for a graphics primitive from a set of at least two candidate rasterization modes based on a metric indicative of an area of the graphics primitive. The haptic feedback device also includes a user interface device, and a transducer configured to impart haptic force to the user interface device in response to the composite signal. The spinal distribution kinetics of the injected or infused drug agent are monitored quantitatively and non-invasively using water proton directional diffusion MR imaging to establish the efficacy of drug delivery at a targeted location.