MRI exams for patients with pacemakers ICDs are contraindicated at all clinical field strengths. One principal concern is radiofrequency (RF) induced lead-tip heating, which may transiently or irreversibly damage tissue at the lead tip and inhibit pacing. The aim of this study was to measure directly RF induced lead tip heating during MRI exams of cadavers with existing devices at both 1.5T and 3T. The data show that pacemaker lead tip temperature increases were below 4C for all cadavers at both 1.5T and 3T over a range of iso-center positions despite the lack of cooling from tissue perfusion.Experiments were conducted with six (N=6) cadavers (Table 1). Three to four fiberoptic temperature probes were implanted adjacent to the right atrial (RA), right ventricular (RV) and/or abandoned lead-tips under x-ray guidance (Figure 1). Whole body CT (1mm isotropic resolution) was used to measure the tip-to-tip distances of leads and temperature probes. Each cadaver was exposed to 4W/kg whole body SAR for 15-minutes at each of five different iso-center positions both at 1.5T and 3T (Siemens Avanto and Prisma). The first iso-center position was 6cm superior to the chin (LM₁) and the other four iso-center positions were in 15cm increments inferior to the first position (LM₂ to LM₅). The maximum temperature increase (∆T_Max) was calculated as the difference between the maximum temperature after 15 minutes of RF exposure and a 20 second average before RF exposure. For single chamber pacemakers a temperature probe was placed at the lead tip; for dual chamber pacemakers the temperature probes were placed at the RA and RV lead tips; for the cadaver with abandoned leads two temperature probes were placed close to the attached lead tip. In all cases the remaining probes were placed in remote tissues for reference.All temperature probes were ≤10mm (5.74±2.59mm) from the lead-tip (Table 2). However, in cadaver 2 the temperature sensor was too distant from the RV lead tip to obtain temperature data. In the absence of perfusion, it is assumed that the duration of RF exposure (15-minutes) was sufficient to ensure nearly maximum heating at the probe location. Figure 1 shows the location of the probes. Figure 2 shows ∆T_Max for each probe in each cadaver at both 1.5T and 3T. Maximum lead tip heating was observed at LM₂ and LM₃ for which the pacemaker/ICD+lead was closest to the body transmit coil isocenter. ∆T_Max was >2C for 8 of 25 cases at 1.5T and for 12 of 25 cases at 3T, but never exceeded 4C. Note that for 6 of these 8 cases at 1.5T and 10 of these 12 cases at 3T the background body temperature also increased >2C.The lead tip heating results were very similar at 1.5T and 3T. The number of cases covered here is limited, but with an increased number of cases these data will be helpful to evaluate the potential severity of RF induced lead tip heating during routine clinical MRI scans. A distinct advantage of these experiments is that they mimic as closely as possible clinical MRI exams for living subjects except for the lack of perfusion. The lack of perfusion, however, creates a “worst-case-scenario” and despite the lack of perfusion ∆T_Max did not exceed 4C for any measure. Note that each implanted device was evaluated in the original position found at the time of death. Consequently, the results do not represent the maximum possible heating for that subject and device, which may only be found through considerable manipulation of the subject or through simulation. High resolution MRI was acquired for each cadaver, which is amenable to simulation and is the subject of future work. Future work should also perform an analysis that calculates the coupled RF power to the implants at both 1.5T and 3T. Pacemaker lead tip temperature increases were below 4C for all cadavers at both 1.5T and 3T over a range of iso-center positions despite the lack of cooling from tissue perfusion. The results are encouraging, but further work is needed before clinical exams for patients with implanted ICD/pacemakers can be judiciously acquire at 3T.