1.5 tesla mri scanner

We assessed previously obtained T1-weighted anatomical data using a 1.5 Tesla MRI scanner (General Electric, Waukesha, WI, USA). For the current study, all ante-mortem MRI data were acquired using a three-dimensional magnetization-prepared rapid acquisition gradient echo (MPRAGE) sequence with parameters echo time (TE) = 2.8 msec, repetition time (TR) = 6.3 msec, preparation time = 1000 msec, flip angle 8°, field of view 24 × 24 cm, 160 slices, 1-mm slice thickness, a 224 × 192 acquisition matrix reconstructed to 256 × 256, and two repetitions. The MRI data were automatically segmented with FreeSurfer 5.0 (http://surfer.nmr.mgh.harvard.edu, for additional details see reference 19 (link)). Here, we focused on intracranial volume corrected average thickness of the entire entorhinal cortex and posterior parahippocampal gyrus (average of left and right hemispheres) as delineated using our previously developed automated cortical parcellation atlas^{11 (link)} (Figure 1). In secondary analyses, we also evaluated baseline intracranial volume corrected hippocampal volumes (average of left and right hemispheres). ^{20 (link)}

All MRI data were acquired on a 1.5 Tesla MRI scanner (General Electric
Medical Systems, Milwaukee, WI) at the Veterans Affairs Palo Alto Health Care
System. Participants were positioned on the scanner bed so that head movements
were restricted. The following structural MR sequences were done on all
participants using a standard head coil: a) a spin-echo, sagittal localizer 2D
sequence of 5 mm thick slices (acquisition time = 1 min 44 s); b) a
proton density and T2-weighted spin-echo MRI, TR/TE1/TE2 = 5000/30/80
ms, 51 oblique axial 3 mm slices covering the entire brain and angulated
parallel to the long axis of the hippocampal formation (1.00 × 1.00
mm² in plane resolution, acquisition time = 17 min); c) a
3D fast spoiled gradient recall acquisition, TR/TE = 9/2 ms, 15°
flip angle, perpendicular to the long axis of the hippocampi (1 × 1
mm² in plane resolution, 1.5 mm coronal slices covering the
entire brain, no skip, acquisition time = 7 min 58 s).