title: Water diffusion measurements in perfused human hippocampal slices undergoing tonicity changes.
abstract: Diffusion MRI has the potential to probe the compartmental origins of MR signals acquired from human nervous tissue. However, current experiments in human subjects require long diffusion times, which may confound data interpretation due to the effects of compartmental exchange. To investigate human nervous tissue at shorter diffusion times, and to determine the relevance of previous diffusion studies in rat hippocampal slices, water diffusion in 20 perfused human hippocampal slices was measured using a wide-bore 17.6-T magnet equipped with 1000-mT/m gradients. These slices were procured from five patients undergoing temporal lobectomy for epilepsy. Tissue viability was confirmed with electrophysiological measurements. Diffusion-weighted water signal attenuation in the slices was well-described by a biexponential function (R(2) > 0.99). The mean diffusion parameters for slices before osmotic perturbation were 0.686 +/- 0.082 for the fraction of fast diffusing water (F(fast)), 1.22 +/- 0.22 x 10(-3) mm(2)/s for the fast apparent diffusion coefficient (ADC), and 0.06 +/- 0.02 x 10(-3) mm(2)/s for the slow ADC. Slice perturbations with 20% hypotonic and 20% hypertonic artificial cerebrospinal fluid led to changes in F(fast) of -8.2% and +10.1%, respectively (ANOVA, P < 0.001). These data agree with previous diffusion studies of rat brain slices and human brain in vivo, and should aid the development of working models of water diffusion in nervous tissue, and thus increase the clinical utility of diffusion MRI.
authors.affiliation: Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, Florida 32610, USA. tms@ufbi.ufl.edu
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Shepherd
authors.forename: Edward D
authors.initials: ED
authors.lastname: Wirth
authors.forename: Peter E
authors.initials: PE
authors.lastname: Thelwall
authors.forename: Huan-Xin
authors.initials: HX
authors.lastname: Chen
authors.forename: Steven N
authors.initials: SN
authors.lastname: Roper
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Blackband
mesh_terms: D000704:Analysis of Variance; D001834:Body Water / Q000378:metabolism*; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging; D004833:Epilepsy, Temporal Lobe / Q000378:metabolism* / Q000601:surgery; D005240:Feasibility Studies; D006624:Hippocampus / Q000378:metabolism* / Q000601:surgery; D006801:Humans