Target-specific rCBF changes induced by 0.3-T static magnetic field exposure on the brain.

The magnetic field has been regarded as both harmful and beneficial for its applications on human brains including transcranial magnetic stimulation (TMS), but its effects still remain in question. Here, we determined using single photon emission computed tomography (SPECT) if 0.3-T static magnetic field could alter regional cerebral blood flow (rCBF) in target and other brain regions in healthy subjects. The permanent static magnet (0.3 T, unipolar, disk shaped, 4 cm diameter and 1 cm thick) was placed on the right frontotemporal region of the brain for each of 14 healthy subjects. Tc-99m ECD perfusion SPECT was taken to compare the CBF patterns in the subjects exposed to the static magnet field with those of the resting and sham conditions. We found that the rCBF was significantly increased in the right frontal and parietal regions and the right insula. On the other hand, rCBF was rather decreased in the left frontal and left parietal regions (P<0.05). These results of this basic study suggest that 0.3-T static magnetic field induces an increase in rCBF in the targeted brain areas non-invasively, which may result from a decrease in rCBF in contralateral regions.