<s>
Molecular	B-Algorithm
imaging	I-Algorithm
is	O
a	O
field	O
of	O
medical	B-Application
imaging	I-Application
that	O
focuses	O
on	O
imaging	O
molecules	O
of	O
medical	O
interest	O
within	O
living	O
patients	O
.	O
</s>
<s>
The	O
most	O
common	O
example	O
of	O
molecular	B-Algorithm
imaging	I-Algorithm
used	O
clinically	O
today	O
is	O
to	O
inject	O
a	O
contrast	B-Algorithm
agent	I-Algorithm
(	O
e.g.	O
,	O
a	O
microbubble	O
,	O
metal	B-Algorithm
ion	I-Algorithm
,	O
or	O
radioactive	O
isotope	O
)	O
into	O
a	O
patient	O
's	O
bloodstream	O
and	O
to	O
use	O
an	O
imaging	B-Application
modality	I-Application
(	O
e.g.	O
,	O
ultrasound	B-Application
,	O
MRI	O
,	O
CT	O
,	O
PET	B-Application
)	O
to	O
track	O
its	O
movement	O
in	O
the	O
body	O
.	O
</s>
<s>
Molecular	B-Algorithm
imaging	I-Algorithm
originated	O
from	O
the	O
field	O
of	O
radiology	O
from	O
a	O
need	O
to	O
better	O
understand	O
fundamental	O
molecular	O
processes	O
inside	O
organisms	O
in	O
a	O
noninvasive	O
manner	O
.	O
</s>
<s>
The	O
ultimate	O
goal	O
of	O
molecular	B-Algorithm
imaging	I-Algorithm
is	O
to	O
be	O
able	O
to	O
noninvasively	O
monitor	O
all	O
of	O
the	O
biochemical	O
processes	O
occurring	O
inside	O
an	O
organism	O
in	O
real	O
time	O
.	O
</s>
<s>
Current	O
research	O
in	O
molecular	B-Algorithm
imaging	I-Algorithm
involves	O
cellular/molecular	O
biology	O
,	O
chemistry	O
,	O
and	O
medical	O
physics	O
,	O
and	O
is	O
focused	O
on	O
:	O
1	O
)	O
developing	O
imaging	O
methods	O
to	O
detect	O
previously	O
undetectable	O
types	O
of	O
molecules	O
,	O
2	O
)	O
expanding	O
the	O
number	O
and	O
types	O
of	O
contrast	B-Algorithm
agents	I-Algorithm
available	O
,	O
and	O
3	O
)	O
developing	O
functional	O
contrast	B-Algorithm
agents	I-Algorithm
that	O
provide	O
information	O
about	O
the	O
various	O
activities	O
that	O
cells	O
and	O
tissues	O
perform	O
in	O
both	O
health	O
and	O
disease	O
.	O
</s>
<s>
Molecular	B-Algorithm
imaging	I-Algorithm
emerged	O
in	O
the	O
mid	O
twentieth	O
century	O
as	O
a	O
discipline	O
at	O
the	O
intersection	O
of	O
molecular	O
biology	O
and	O
in	O
vivo	O
imaging	O
.	O
</s>
<s>
Molecular	B-Algorithm
imaging	I-Algorithm
differs	O
from	O
traditional	O
imaging	O
in	O
that	O
probes	O
known	O
as	O
biomarkers	O
are	O
used	O
to	O
help	O
image	O
particular	O
targets	O
or	O
pathways	O
.	O
</s>
<s>
Furthermore	O
,	O
molecular	B-Algorithm
imaging	I-Algorithm
allows	O
for	O
quantitative	O
tests	O
,	O
imparting	O
a	O
greater	O
degree	O
of	O
objectivity	O
to	O
the	O
study	O
of	O
these	O
areas	O
.	O
</s>
<s>
One	O
emerging	O
technology	O
is	O
MALDI	O
molecular	B-Algorithm
imaging	I-Algorithm
based	O
on	O
mass	O
spectrometry	O
.	O
</s>
<s>
Many	O
areas	O
of	O
research	O
are	O
being	O
conducted	O
in	O
the	O
field	O
of	O
molecular	B-Algorithm
imaging	I-Algorithm
.	O
</s>
<s>
Organizations	O
such	O
as	O
the	O
SNMMI	O
Center	O
for	O
Molecular	B-Algorithm
Imaging	I-Algorithm
Innovation	O
and	O
Translation	O
(	O
CMIIT	O
)	O
have	O
formed	O
to	O
support	O
research	O
in	O
this	O
field	O
.	O
</s>
<s>
In	O
Europe	O
,	O
other	O
"	O
networks	O
of	O
excellence	O
"	O
such	O
as	O
DiMI	O
(	O
Diagnostics	O
in	O
Molecular	B-Algorithm
Imaging	I-Algorithm
)	O
or	O
EMIL	O
(	O
European	O
Molecular	B-Algorithm
Imaging	I-Algorithm
Laboratories	O
)	O
work	O
on	O
this	O
new	O
science	O
,	O
integrating	O
activities	O
and	O
research	O
in	O
the	O
field	O
.	O
</s>
<s>
In	O
this	O
way	O
,	O
a	O
European	O
Master	O
Programme	O
"	O
EMMI	O
"	O
is	O
being	O
set	O
up	O
to	O
train	O
a	O
new	O
generation	O
of	O
professionals	O
in	O
molecular	B-Algorithm
imaging	I-Algorithm
.	O
</s>
<s>
Recently	O
the	O
term	O
molecular	B-Algorithm
imaging	I-Algorithm
has	O
been	O
applied	O
to	O
a	O
variety	O
of	O
microscopy	O
and	O
nanoscopy	O
techniques	O
including	O
live-cell	O
microscopy	O
,	O
Total	O
Internal	O
Reflection	O
Fluorescence	O
(	O
TIRF	O
)	O
-microscopy	O
,	O
STimulated	O
Emission	O
Depletion	O
(	O
STED	O
)	O
-nanoscopy	O
and	O
Atomic	O
Force	O
Microscopy	O
(	O
AFM	O
)	O
as	O
here	O
images	O
of	O
molecules	O
are	O
the	O
readout	O
.	O
</s>
<s>
There	O
are	O
many	O
different	O
modalities	O
that	O
can	O
be	O
used	O
for	O
noninvasive	O
molecular	B-Algorithm
imaging	I-Algorithm
.	O
</s>
<s>
To	O
achieve	O
molecular	B-Algorithm
imaging	I-Algorithm
of	O
disease	O
biomarkers	O
using	O
MRI	O
,	O
targeted	O
MRI	B-Algorithm
contrast	I-Algorithm
agents	I-Algorithm
with	O
high	O
specificity	O
and	O
high	O
relaxivity	O
(	O
sensitivity	O
)	O
are	O
required	O
.	O
</s>
<s>
To	O
date	O
,	O
many	O
studies	O
have	O
been	O
devoted	O
to	O
developing	O
targeted-MRI	O
contrast	O
agents	O
to	O
achieve	O
molecular	B-Algorithm
imaging	I-Algorithm
by	O
MRI	O
.	O
</s>
<s>
To	O
enhance	O
the	O
sensitivity	O
of	O
the	O
contrast	B-Algorithm
agents	I-Algorithm
,	O
these	O
targeting	O
moieties	O
are	O
usually	O
linked	O
to	O
high	O
payload	O
MRI	B-Algorithm
contrast	I-Algorithm
agents	I-Algorithm
or	O
MRI	B-Algorithm
contrast	I-Algorithm
agents	I-Algorithm
with	O
high	O
relaxivities	O
.	O
</s>
<s>
Optical	O
imaging	O
's	O
most	O
valuable	O
attribute	O
is	O
that	O
it	O
and	O
ultrasound	B-Application
do	O
not	O
have	O
strong	O
safety	O
concerns	O
like	O
the	O
other	O
medical	B-Application
imaging	I-Application
modalities	O
.	O
</s>
<s>
The	O
imaging	O
agent	O
used	O
in	O
SPECT	O
emits	O
gamma	O
rays	O
,	O
as	O
opposed	O
to	O
the	O
positron	O
emitters	O
(	O
such	O
as	O
)	O
used	O
in	O
PET	B-Application
.	O
</s>
<s>
Xenon	B-Protocol
(	O
)	O
gas	O
is	O
one	O
such	O
radiotracer	O
.	O
</s>
<s>
This	O
represents	O
the	O
major	O
advantage	O
of	O
SPECT	O
as	O
a	O
molecular	B-Algorithm
imaging	I-Algorithm
technique	O
,	O
since	O
it	O
is	O
significantly	O
cheaper	O
than	O
either	O
PET	B-Application
or	O
fMRI	O
.	O
</s>
<s>
However	O
it	O
lacks	O
good	O
spatial	O
(	O
i.e.	O
,	O
where	O
exactly	O
the	O
particle	O
is	O
)	O
or	O
temporal	O
(	O
i.e.	O
,	O
did	O
the	O
contrast	B-Algorithm
agent	I-Algorithm
signal	O
happen	O
at	O
this	O
millisecond	O
,	O
or	O
that	O
millisecond	O
)	O
resolution	O
.	O
</s>
<s>
Additionally	O
,	O
due	O
to	O
the	O
radioactivity	O
of	O
the	O
contrast	B-Algorithm
agent	I-Algorithm
,	O
there	O
are	O
safety	O
aspects	O
concerning	O
the	O
administration	O
of	O
radioisotopes	O
to	O
the	O
subject	O
,	O
especially	O
for	O
serial	O
studies	O
.	O
</s>
<s>
Positron	B-Application
emission	I-Application
tomography	I-Application
(	O
PET	B-Application
)	O
is	O
a	O
nuclear	O
medicine	O
imaging	O
technique	O
which	O
produces	O
a	O
three-dimensional	O
image	O
or	O
picture	O
of	O
functional	O
processes	O
in	O
the	O
body	O
.	O
</s>
<s>
The	O
theory	O
behind	O
PET	B-Application
is	O
simple	O
enough	O
.	O
</s>
<s>
One	O
of	O
the	O
major	O
disadvantages	O
of	O
PET	B-Application
is	O
that	O
most	O
of	O
the	O
probes	O
must	O
be	O
made	O
with	O
a	O
cyclotron	O
.	O
</s>
<s>
These	O
factors	O
can	O
make	O
PET	B-Application
prohibitively	O
expensive	O
.	O
</s>
<s>
PET	B-Application
imaging	I-Application
does	O
have	O
many	O
advantages	O
though	O
.	O
</s>
<s>
First	O
and	O
foremost	O
is	O
its	O
sensitivity	O
:	O
a	O
typical	O
PET	B-Application
scanner	I-Application
can	O
detect	O
between	O
10−11	O
mol/L	O
to	O
10−12	O
mol/L	O
concentrations	O
.	O
</s>
