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AJNR - American Journal of Neuroradiology

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Quantitative MR Imaging R₂ Relaxometry in Elderly Participants Reporting Memory Loss

M.J. House^a, T.G. St. Pierre^a, J.K. Foster^b,c, R.N. Martins^b and R. Clarnette^d

^a School of Physics, University of Western Australia
^b School of Exercise, Biomedical and Sports Sciences, Health Department of Western Australia
^c Edith Cowan University and Neurosciences Unit, Health Department of Western Australia
^d Department of Community and Geriatric Medicine, Fremantle Hospital

View larger version (92K): [in a new window]   Fig 1. Representative spin-echo images (TE = 6 ms) of the anterior (A) and posterior (B) coronal sections of a control subject. The 14 gray and white matter regions for which R2 data were acquired are shown as representative regions of interest. Lateral frontal cortex (1), lateral temporal cortex (2), corpus callosum (body) (3), caudate nucleus (4), internal capsule (anterior limb) (5), subcortical frontal white matter (6), frontal white matter (7), putamen (8), globus pallidus (9), temporal white matter (10), hippocampus (11), red nucleus (12), thalamus (13), and substantia nigra (14), The 3 circular objects surrounding the head are MnCl2-doped water bags that were used as part of another experiment not described here. The red nucleus is not well defined on this image and was typically delineated on longer echo-time images.

View larger version (34K): [in a new window]   Fig 2. Mean R2 values of the control participants for 10 brain regions versus postmortem iron content of normal individuals. Error bars represent SD. Iron concentrations from Hallgren and Sourander.21 Note that frontal (FW) and subcortical frontal white matter (SCFW) regions from this study have been assigned the same iron concentration, because Hallgren and Sourander21 provide iron data for frontal white matter only. CN = caudate nucleus; FG = frontal cortex gray; FW = frontal cortex white; GP = globus pallidus; PUT = putamen; RN = red nucleus; SCFW = subcortical frontal white; SN = substantia nigra; TG = temporal cortex gray; TH = thalamus.

View larger version (36K): [in a new window]   Fig 3. R2 values for temporal cortex gray matter (A), the internal capsule (B), temporal cortex white matter (C), and the hippocampus (D) for the control participants and memory-complaint subgroups MC1 and MC2. Error bars around the mean are SD. *Significant difference between controls and MC1 or MC2 (P < .05, one-tailed t test). #Significant difference between controls and MC1 or MC2 (P < .05, after ANCOVA adjustment for age where applicable). Significant difference between MC1 and MC2 (P < .05, one-tailed t test).

View larger version (50K): [in a new window]   Fig 4. Plot of R2 differences between the MC1 subgroup and controls (A), and the MC2 subgroup and controls (B), for the left and right hemispheres. CC = corpus callosum; CN = caudate nucleus; FG = frontal cortex gray; FW = frontal cortex white; GP = globus pallidus; HP = hippocampus; IC = internal capsule; PUT = putamen; RN = red nucleus; SCFW = subcortical frontal white; SN = substantia nigra; TG = temporal cortex gray; TH = thalamus; TW = temporal cortex white. *Significant difference between controls and MC1 or MC2 (P < .05, one-tailed t test). #Significant difference between controls and MC1 or MC2 (P < .05, after ANCOVA adjustment for age where applicable).