Diffusion magnetic resonance imaging in the head and neck.

Diffusion weighting (DW) represents a magnetic resonance imaging contrast distinct from T1 and T2 in terms of imaging physics and its relationship to underlying physiology and pathophysiology. DW imaging has become a sine qua non of neuroimaging because of its exquisite sensitivity to the molecular motion of water that is altered in many pathologic conditions including acute ischemia. This article reviews the physical principles of DW imaging in the head and neck and describes how it can help to solve this and several other related problems.