A Measurement-based Temperature-Matrix approach is presented that enables a fast, patient and exam specific estimation and mitigation of RF hazards of implants. Various locations in phantom are tested using an 8-channel (300MHz) implant safety testbed. Heating reduction Based on T-Matrix Measurements resulted >3 times heating reduction vs. circularly-polarized mode and >19 times vs. worst-case mode. 2-channel MRI (3T) feasibility experiments using high temperature resolution showed good correlation with transmitted power. In addition, T-matrix-based temperature increase predictions successfully demonstrated. As summary, an easy to implement, cheap, sensor-based method, the T-matrix, to investigate, characterize and mitigate RF heating of implants is introduced.