Biomedical Engineering Reference
In-Depth Information
FIGURE 16.53
Example of functional MRI imaging of human brain responses. (A) The grey nearly horizontal
line through the top sagittal slice of the brain at the left (denoted by a “0”) shows the position of the three axial
slices to the right. On the upper right are group
maps showing statistically significant, group averaged neural
activity for each experiment: biological movement (BM), face-gender, and nonrigid motion (NRM). To generate
these
z
z
maps for each experiment, a
t
test was performed to contrast each experiment's task with the control.
The grey scale represents the
score of the activation. Note most of the activity is in the KO region and the lateral
cerebellum. On the bottom left, the lines through the cerebellum in the sagittal slice indicate the angulation of the
coronal cut. To the right, the three coronal slices (arranged vertically) show that only BM had activity in the lateral
cerebellum.
z
From [4].
pathways are verified, as well as the ability of a subject to selectively focus attention on
either a “where” or “what” aspect. Dipole locations as calculated from received MEG sig-
nals on the semispherical grid are indicated on corresponding MRI images.
MEG is used to explore the characteristics of mental patterns such as epilepsy and
schizophrenia. It is also useful in brain research to understand cognitive functioning and
to learn which parts of the brain are involved in different tasks.
16.5 CONTRAST AGENTS
Contrast agents emphasize or magnify physiological features or functions that would
otherwise be invisible, weak, or obscured in images. One of the most frequent applications
of these agents is in the vasculature. Another is the uptake of an agent by an organ, indicat-
ing a degree of functional or metabolic activity. Each agent is designed to work with the
particular physics of the intended imaging modality as well as the region of indication in
the body.
