Toward Understanding SAR patterns in the Human Head at High Field (200 to 400 MHz) MRI with Volume Coils
Smith M, Collins C, Wang Z
Penn State College of Medicine
Some recent numerical calculations have indicated a region of relatively high SAR near the center of the brain (1, 2). This can seem counter-intuitive from analytical theory, which predicts a low-SAR region near the center of a symmetric sample in a symmetric magnetic field (3). Here we compare SAR distributions in a homogeneous, symmetric sample (sphere) placed in the center of a volume coil with those for a heterogeneous human head with the majority of brain above the coil center. It is seen that in this case the overall pattern in the brain has some similarities to that in the upper half of the sphere, helping to explain the region of high SAR near the center of the brain.