MRI measurement of cell volume fraction in the perfused rat hippocampal slice

T-1-weighted NMR imaging of the isolated perfused rat hippocampal slice was used to estimate cell Volume fraction. Eight brain slices were studied in artificial cerebrospinal fluid (aCSF) using a 600 MHz narrow bore spectrome ter and a home built perfusion chamber. Cell volume fraction was calculated as 1 - f(ECS), where f(ECS) is the distribution volume of gadodiamide in t he slice. This was determined by measuring the T-1 of the slice before and after perfusion with gadodiamde. A mean cell volume fraction of 0.66 +/- 0. 04 was estimated. The addition of 60 mM mannitol to three of the brain slic es produced a 26% decrease in the cell volume fraction. The technique affor ds a simple means of estimating cell volume fraction and can be extended to produce images reflecting cell density. (C) 1999 Wiley-Liss, Inc.