<s>
Brain	B-Algorithm
positron	I-Algorithm
emission	I-Algorithm
tomography	I-Algorithm
is	O
a	O
form	O
of	O
positron	B-Application
emission	I-Application
tomography	I-Application
(	O
PET	O
)	O
that	O
is	O
used	O
to	O
measure	O
brain	O
metabolism	O
and	O
the	O
distribution	O
of	O
exogenous	O
radiolabeled	O
chemical	O
agents	O
throughout	O
the	O
brain	O
.	O
</s>
<s>
The	O
emission	O
data	O
from	O
brain	B-Algorithm
PET	I-Algorithm
are	O
computer-processed	O
to	O
produce	O
multi-dimensional	O
images	O
of	O
the	O
distribution	O
of	O
the	O
chemicals	O
throughout	O
the	O
brain	O
.	O
</s>
<s>
Detectors	O
in	O
the	O
PET	B-Application
scanner	I-Application
detect	O
the	O
radioactivity	O
as	O
the	O
compound	O
charges	O
in	O
various	O
regions	O
of	O
the	O
brain	O
.	O
</s>
<s>
Especially	O
useful	O
are	O
a	O
wide	O
array	O
of	O
ligands	O
used	O
to	O
map	O
different	O
aspects	O
of	O
neurotransmitter	O
activity	O
,	O
with	O
by	O
far	O
the	O
most	O
commonly	O
used	O
PET	O
tracer	O
being	O
a	O
labeled	O
form	O
of	O
glucose	O
,	O
such	O
as	O
fluorodeoxyglucose	B-Application
(	O
18F	O
)	O
.	O
</s>
<s>
The	O
greatest	O
benefit	O
of	O
PET	O
scanning	O
is	O
that	O
different	O
compounds	O
can	O
show	O
flow	B-Algorithm
and	I-Algorithm
oxygen	I-Algorithm
,	O
and	O
glucose	O
metabolism	O
in	O
the	O
tissues	O
of	O
the	O
working	O
brain	O
.	O
</s>
<s>
PET	B-Application
scans	I-Application
were	O
superior	O
to	O
all	O
other	O
metabolic	O
imaging	O
methods	O
in	O
terms	O
of	O
resolution	O
and	O
speed	O
of	O
completion	O
(	O
as	O
little	O
as	O
30	O
seconds	O
)	O
,	O
when	O
they	O
first	O
became	O
available	O
.	O
</s>
<s>
Before	O
the	O
use	O
of	O
functional	B-Algorithm
magnetic	I-Algorithm
resonance	I-Algorithm
imaging	I-Algorithm
(	O
fMRI	B-Algorithm
)	O
became	O
widespread	O
,	O
PET	O
scanning	O
was	O
the	O
preferred	O
method	O
of	O
functional	O
(	O
as	O
opposed	O
to	O
structural	O
)	O
brain	O
imaging	O
,	O
and	O
it	O
still	O
continues	O
to	O
make	O
large	O
contributions	O
to	O
neuroscience	O
.	O
</s>
<s>
PET	O
scanning	O
is	O
also	O
used	O
for	O
diagnosis	O
of	O
brain	O
disease	O
,	O
most	O
notably	O
because	O
brain	O
tumors	O
,	O
strokes	O
,	O
and	O
neurondegenerative	O
diseases	O
(	O
such	O
as	O
Alzheimer	O
's	O
disease	O
and	O
Parkinson	O
's	O
disease	O
)	O
all	O
cause	O
great	O
changes	O
in	O
brain	O
metabolism	O
,	O
which	O
in	O
turn	O
causes	O
detectable	O
changes	O
in	O
PET	B-Application
scans	I-Application
.	O
</s>
<s>
PET	B-Application
imaging	I-Application
with	O
oxygen-15	O
indirectly	O
measures	O
blood	O
flow	O
to	O
the	O
brain	O
.	O
</s>
<s>
PET	B-Application
imaging	I-Application
with	O
18F-FDG	B-Application
takes	O
advantage	O
of	O
the	O
fact	O
that	O
the	O
brain	O
is	O
normally	O
a	O
rapid	O
user	O
of	O
glucose	O
.	O
</s>
<s>
Standard	O
18F-FDG	B-Application
PET	O
of	O
the	O
brain	O
measures	O
regional	O
glucose	O
use	O
and	O
can	O
be	O
used	O
in	O
neuropathological	O
diagnosis	O
.	O
</s>
<s>
Therefore	O
18F-FDG	B-Application
PET	O
of	O
the	O
brain	O
may	O
also	O
be	O
used	O
to	O
successfully	O
differentiate	O
Alzheimer	O
's	O
disease	O
from	O
other	O
dementing	O
processes	O
,	O
and	O
also	O
to	O
make	O
early	O
diagnoses	O
of	O
Alzheimer	O
's	O
disease	O
.	O
</s>
<s>
The	O
advantage	O
of	O
18F-FDG	B-Application
PET	O
for	O
these	O
uses	O
is	O
its	O
much	O
wider	O
availability	O
.	O
</s>
<s>
Examples	O
:	O
PET	B-Application
imaging	I-Application
with	O
FDG	O
can	O
also	O
be	O
used	O
for	O
localization	O
of	O
seizure	O
focus	O
:	O
A	O
seizure	O
focus	O
will	O
appear	O
as	O
hypometabolic	O
during	O
an	O
interictal	O
scan	O
.	O
</s>
<s>
Example	O
:	O
PET	B-Application
imaging	I-Application
with	O
18F-FDG	B-Application
can	O
be	O
used	O
to	O
estimate	O
glucose	O
metabolism	O
in	O
acute	O
ischemic	O
stroke	O
.	O
</s>
<s>
Some	O
traces	O
used	O
for	O
ischemic	O
stroke	O
are	O
Oxygen-15	B-Algorithm
labelled	I-Algorithm
water	I-Algorithm
,	O
[18F]FMISO	O
.	O
</s>
<s>
The	O
development	O
of	O
a	O
number	O
of	O
novel	O
probes	O
for	O
noninvasive	O
,	O
in	O
vivo	O
PET	B-Application
imaging	I-Application
of	O
neuroaggregate	O
in	O
human	O
brain	O
has	O
brought	O
amyloid	O
imaging	O
to	O
the	O
doorstep	O
of	O
clinical	O
use	O
.	O
</s>
<s>
[11C]PMP	O
(	O
N-	O
 [ 11C ] 	O
methylpiperidin-4-yl	O
propionate	O
)	O
is	O
a	O
novel	O
radiopharmaceutical	O
used	O
in	O
PET	B-Application
imaging	I-Application
to	O
determine	O
the	O
activity	O
of	O
the	O
acetylcholinergic	O
neurotransmitter	O
system	O
by	O
acting	O
as	O
a	O
substrate	O
for	O
acetylcholinesterase	O
.	O
</s>
<s>
Avid	O
Radiopharmaceuticals	O
has	O
developed	O
and	O
commercialized	O
a	O
compound	O
called	O
florbetapir	O
that	O
uses	O
the	O
longer-lasting	O
radionuclide	O
fluorine-18	O
to	O
detect	O
amyloid	O
plaques	O
using	O
PET	B-Application
scans	I-Application
.	O
</s>
