Biomedical Engineering Reference
In-Depth Information
(a)
(b)
Figure 1.
Sample postmortem coronal slices: (a) slice 50 from half-brain of a control case;
(b) slice 60 from whole brain of an autistic subject.
These techniques demonstrate good results in samples fixed for from 6 weeks to
15 months [48]. All images were acquired with the same 1.5-T Signa MRI scanner
(General Electric, Milwaukee, WI) using a 3D spoiled gradient recall acquisition
in the steady state (time to echo, 5 ms; time to repeat, 24 ms; flip angle, 45
◦
;
repetition, 1; field of view, 24 cm
2
). Contiguous axial slices 1
.
5 mm thick (124
per brain), were obtained. The images were collected in a 192
×
256 acquisition
matrix and were 0-filled in the k space to yield an image of 256
×
256 pixels
2
,
resulting in an effective voxel resolution of approximately 1
.
0
×
1
.
0
×
1
.
5 mm
3
.
The acquired datasets are PD-weighted volumes of size 512
×
512
×
114.
Each slice is 1.6 mm thick with an in-plane resolution of 0
.
625
×
0
.
3125 mm
2
,on
which the WM appears dark, the GM appears light, and the fluid appears brighter.
Due to different factors including removal of the brain from the skull and fixation
problems, distortions such as large deep cuts commonly occur and are revealed in
the MRI scans. Sample slices of the postmortem data are shown in Figure 1.
The savant datasets were acquired with the same 1.5-T Signa MRI scanner
(General Electric, Milwaukee, WI) using a 3D spoiled gradient recall acquisition
in the steady state (time to echo, 5 ms; time to repeat, 24 ms; flip angle, 45
◦
;
repetition, 1; field of view, 24 cm
2
). Contiguous axial slices (1.5 mm thick)
or coronal slices (2 mm thick) were obtained, 124 per brain. The images were
collected in a 192
×
256 acquisition matrix and were 0-filled in the k space to yield
an image of 256
×
256 pixels, resulting in an effective voxel resolution of 0.9375
×
1.5 mm
3
(or 0
.
9375
×
0
.
9375
×
2 mm
3
). Subject placement was
standardized. A total of 30 normals and 15 autistic brain datasets were collected.
0.9375
×
