In Vivo Radiofrequency Heating due 1.5, 3 and 7 T Whole-body Volume Coils

In vivo heating due to radiofrequency (RF) power deposition from transmit coils is a safety concern during magnetic resonance imaging (MRI). Thus, to better understand such heating and related tissue effects, a computational study is performed to systematically analyze the RF power distribution, related temperature rise, and accumulated thermal dose during heating, in an adult male, an adult female, and a pregnant woman due to power deposition from a 1.5, 3, and 7 T whole-body volume coil. Four landmark positions - head, heart, trunk, and pelvis - were studied. RF power distribution is computed by solving Maxwell equations. Resultant tissue heating is simulated by solving the first principles based, previously validated, generic bioheat transfer model (GBHTM) and empirical, traditional Pennes bioheat transfer equation (BHTE). Accumulated thermal dose is computed using the cumulative equivalent minutes @ 43 degrees C (CEM43) and Arrhenius equation (Omega)-based approaches. Results show that allowable whole-body average RF power and energy depositions may result in local and systemic temperature rise exceeding allowable temperature limits. Also, local thermal dose may exceed CEM43 of 60 min and equivalent Arrhenius equation based nondimensional thermal dose Omega of 0.02.