Evaluation of MR-induced hot spots for different temporal SAR modes using a time-dependent finite difference method with explicit temperature gradient treatment.

An investigation of magnetic resonance (MR)-induced hot spots in a high-resolution human model is performed, motivated by safety aspects for the use of MR tomographs. The human model is placed in an MR whole body resonator that is driven in a quadrature excitation mode. The MR-induced hot spots are studied by varying the following: (1) the temporal specific absorption rate (SAR) mode ("steady imaging", "intermittent imaging"), (2) the simulation procedure (related to given power levels or to limiting temperatures), and (3) different thermal tissue properties including temperature-independent and temperature-dependent perfusion models.

Specific absorption rate as a poor indicator of magnetic resonance-related implant heating.

Recent publications of the magnetic resonance safety profile of neurostimulators, cardiac pacemakers, and other implanted devices imply that these devices are no longer a contraindication for magnetic resonance imaging. It is very promising that patients who have these implanted devices may in the future no longer be denied an important diagnostic modality. On the other hand, the safety recommendations given in a number of publications included the maximum permissible whole-body specific absorption rate (SAR).