Blood oxygenation level dependent functional magnetic resonance imaging

Abstract

The objective of the present article is to provide an introduction to the most widely used method of imaging the functional neuroanatomy of the human brain. The inferential relationship between neural activation and a magnetic resonance signal change is described in detail. The contrast between an active state and a baseline depends on an increased ratio of oxyhemoglobin to deoxyhemoglobin, a longer transverse relaxation time (T 2*), decreased levels of paramagnetically induced dephasing, and a consequently stronger signal in the active state. Issues pertaining to image interpretation, spatial and temporal resolution, and image stability are described. © 2003 Wiley Periodicals, Inc.