Signa premier 3t scanner

MR images were acquired in a General Electric Signa Premier 3T scanner and processed with FreeSurfer (v6.0 http://surfer.nmr.mgh.harvard.edu/). The measure of neurodegeneration was the average cortical thickness from regions typically affected by AD [21 (link)], including entorhinal cortex, parahippocampus, inferior parietal lobule, pars opercularis, pars orbitalis, pars triangularis, inferior temporal pole, supramarginal gyrus, superior parietal lobe, and superior frontal lobe. White matter hyperintensity volume was derived with in-house developed software. Briefly, each participant’s T2-weighted FLAIR MRI scan was intensity normalized and brain extracted. A Gaussian mixture model was fit to the log-transformed distribution of voxel intensity values. The voxels included in the Gaussian distribution that comprised the highest intensity values were labeled, summed, and multiplied by voxel dimensions to yield total WMH volumes in cm^3. Labeled images were visually inspected and edited if necessary. We used the ratio of total WMH and total cranial volume (TCV) for analyses. Total WMH in cm³ was defined as the sum of the number of voxels that are labeled multiplied by voxel dimensions. We used the ratio of total WMH and total cranial volume (TCV) for analyses.
Verbal learning was ascertained using total recall in the Buschke Selective Reminding test (SRT) [27 (link)].