Is there a change in water proton density associated with functional magnetic resonance imaging?

Open Access
Publisher Website
Google Scholar
Abstract
In a recent series of studies (see, for example, Stroman et al. Magn Reson Imag 2001; 19:827–831), an increase of water proton density has been suggested to correlate with neuronal activity. Owing to the significant implications of such a mechanism for other functional experiments, the functional signal changes in humans at very short echo times were re‐examined by spin‐echo EPI at 3 T. The results do not confirm the previous hypothesis of a significant increase in extravascular proton density at TE = 0. Instead, an alternative explanation of the effect is offered: The use of a low threshold to identify activated voxels may generate an artificial offset in functional contrast due to the inclusion of false‐positives in the analysis. Magn Reson Med 53:470–473, 2005.
Funding Information
  • Federal German Ministry of Education and Research (BMBF) within the framework of German-Israeli project cooperation (DIP)