MR görüntüleme sırasında gradyan sargılar içinde oluşan elektromanyetik alanın analizi ve hastada görülebilecek kalp ve sinir uyarımının incelenmesi

During magnetic resonance imaging (MRI), the static magnetic field, the radio frequency field and the gradient fields are utilized. In the literature, there are different studies in order to understand the bioeffects of these fields. Due to the time varying gradient fields, the electric field is induced in the body and that may cause the nerve and cardiac stimulation. In order to investigate this risk, first researchers have been worked on solving the induced electric field analytically and by using computational methods and the field distribution inside the body has been investigated. It is also vital in order to verify the risk of MRI to the patients with an implant. In order to improve the understandability of the field pattern, the field expression should be as simple as possible.In this thesis, the simplified expressions of induced electric field are derived inside and outside the cylindrical, homogenous volume taken as a human body model. For this derivation, low frequency based assumptions are used and gradient field is assumed to be perfectly uniform. The result satisfies the expected conditions for the electric and magnetic fields. The field patterns obtained with these simplified expressions are compared with the former studies and the maximum electric field values obtained for a different gradient field and slew rate values are used to investigate the stimulation risk. Moreover, by using these electric field values the worst position for an implant lead and the length of the lead is determined.We believe that with these simplified expressions, the understandability of the field distribution is increased and to comment on the risk of the MRI to the patient with implant becomes easier.