Absolute measurements of water content using magnetic resonance imaging: preliminary findings in an in vivo focal ischemic rat model.

Using a magnetic resonance (MR) imaging method, absolute measurements of in vivo brain water content were obtained in 15 male Long Evans rats that underwent a 90-min focal cerebral ischemia. A strong linear relationship (r = 0.80) with a slope of 1 was observed when correlating MR-measured water content to that obtained with the ex vivo wet/dry measurements. This effective spin-density-based method is the first-reported in vivo absolute quantification of brain tissue water content associated with a pathophysiological state and preliminary findings suggest that a noninvasive measurement of brain water content can be obtained with MRI.