Magnetic resonance imaging (MRI) is still contraindicated in patients with implanted active medical devices, as the applied radiofrequency (RF) fields can lead to significant heating of the implants and the electrodes. A head model with an implanted deep brain stimulation electrode (DBS) was exposed to a continuous RF-field similar to the excitational field used in MRI at a frequency of 64 MHz. In this study a two-step procedure for the accurate estimation of electrode-heating during MRI is presented. First the energy loss was calculated in the frequency domain during an applied RF-pulse. Then a thermodynamic algorithm taking heat transfer mechanisms into account was used. The applied method showed to be numerically stable and gave more accurate results than first calculated using a simple worst-case approximation.

The paper presents a simulation of the transient temperature distribution in the human body caused by induced eddy currents during magnetic resonance imaging (MRI). In a first simulation the validity of the used heat conduction equation was proven using a simple example of a cool-down-process of a sphere. Thereafter the heating of a phantom model with an implanted electrode placed in a MRI-System (active body coil) was examined. The resulting increase in temperature was compared with existing measurements. Finally the implications of the heating of the tissue are discussed based on the observed experimental and numerical results.

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The non-surgical treatment of the prostate carcinoma (PC) exist an increased acceptance of the patients. Prerequisite is however an appropriate monitoring as well as the possibility of the restaging (response). To date the inspection results after primary irradiation through the determination of the PSA-NADIR ("Nadir", arabic = base point, deepest PSA value after therapy). After the ASTRO criteria, a recurrent tumor growth exist if a PSA increase of <1.5 ng/ml is detectable. The so-called Bounce phenomenon and the recurrent inflammatory reaction of the prostate tissue demarcate frequently the exact biochemical estimation of the PSA value. After the first hormone therapy of the recidivating prostate carcinoma, presently yet no exact PSA value is determined as a guideline.