<s>
The	O
standardized	B-Algorithm
uptake	I-Algorithm
value	I-Algorithm
(	O
SUV	B-Algorithm
)	O
is	O
a	O
nuclear	O
medicine	O
term	O
,	O
used	O
in	O
positron	B-Application
emission	I-Application
tomography	I-Application
(	O
PET	O
)	O
as	O
well	O
as	O
in	O
modern	O
calibrated	O
single	O
photon	O
emission	O
tomography	O
(	O
SPECT	O
)	O
imaging	O
for	O
a	O
semiquantitative	O
analysis	O
.	O
</s>
<s>
Its	O
use	O
is	O
particularly	O
common	O
in	O
the	O
analysis	O
of	O
[18F]fluorodeoxyglucose	O
(	O
)	O
images	O
of	O
cancer	O
patients	O
.	O
</s>
<s>
It	O
can	O
also	O
be	O
used	O
with	O
other	O
PET	O
agents	O
especially	O
when	O
no	O
arterial	B-Algorithm
input	I-Algorithm
function	I-Algorithm
is	O
available	O
for	O
more	O
detailed	O
pharmacokinetic	O
modeling	O
.	O
</s>
<s>
The	O
SUV	B-Algorithm
is	O
the	O
ratio	O
of	O
the	O
image-derived	O
radioactivity	O
concentration	O
cimg	O
and	O
the	O
whole	O
body	O
concentration	O
of	O
the	O
injected	O
radioactivity	O
cinj	O
,	O
</s>
<s>
Calculated	O
SUV	B-Algorithm
data	O
can	O
then	O
be	O
visualized	O
as	O
parametric	O
SUV	B-Algorithm
image	O
.	O
</s>
<s>
by	O
manually	O
drawing	O
or	O
otherwise	O
segmenting	O
a	O
region	B-Algorithm
of	I-Algorithm
interest	I-Algorithm
(	O
ROI	O
)	O
on	O
the	O
PET	O
image	O
.	O
</s>
<s>
the	O
average	O
intensity	O
of	O
that	O
ROI	O
may	O
be	O
used	O
as	O
cimg	O
input	O
to	O
calculate	O
SUV	B-Algorithm
values	O
.	O
</s>
<s>
Measured	O
SUV	B-Algorithm
values	O
in	O
particular	O
parts	O
of	O
the	O
body	O
thus	O
quantify	O
the	O
deviation	O
from	O
this	O
hypothetical	O
even	O
radioactivity	O
distribution	O
:	O
SUV	B-Algorithm
1	O
indicates	O
radioactivity	O
accumulation	O
in	O
that	O
region	O
above	O
the	O
hypothetical	O
even	O
radioactivity	O
distribution	O
.	O
</s>
<s>
This	O
would	O
give	O
SUV	B-Algorithm
in	O
units	O
of	O
g/mL	O
or	O
equivalent	O
.	O
</s>
<s>
However	O
,	O
SUV	B-Algorithm
is	O
typically	O
presented	O
as	O
a	O
unitless	O
parameter	O
.	O
</s>
<s>
Thus	O
,	O
while	O
the	O
body	O
weight	O
is	O
usually	O
measured	O
and	O
used	O
for	O
the	O
SUV	B-Algorithm
calculation	O
,	O
this	O
is	O
implicitly	O
converted	O
to	O
the	O
body	O
volume	O
in	O
mL	O
by	O
division	O
by	O
1g/mL	O
resulting	O
in	O
a	O
unitless	O
SUV	B-Algorithm
parameter	O
.	O
</s>
<s>
In	O
summary	O
this	O
gives	O
the	O
following	O
equation	O
to	O
calculate	O
SUV	B-Algorithm
at	O
time	O
t	O
post	O
injection	O
,	O
</s>
<s>
In	O
other	O
words	O
,	O
SUV	B-Algorithm
can	O
be	O
interpreted	O
as	O
the	O
%	O
ID/mL	O
normalized	O
to	O
(	O
here	O
,	O
multiplied	O
by	O
)	O
the	O
body	O
weight	O
(	O
or	O
body	O
volume	O
)	O
and	O
expressed	O
as	O
fraction	O
rather	O
than	O
percentage	O
.	O
</s>
<s>
Also	O
for	O
from	O
a	O
region	B-Algorithm
of	I-Algorithm
interest	I-Algorithm
,	O
different	O
measures	O
are	O
found	O
in	O
the	O
literature	O
,	O
e.g.	O
,	O
the	O
maximum	O
intensity	O
value	O
within	O
the	O
ROI	O
,	O
the	O
mean	O
intensity	O
value	O
of	O
the	O
ROI	O
,	O
or	O
the	O
mean	O
intensity	O
value	O
of	O
the	O
ROI	O
after	O
applying	O
an	O
intensity	O
threshold	O
(	O
thus	O
excluding	O
a	O
number	O
of	O
pixels	O
of	O
the	O
ROI	O
)	O
.	O
</s>
<s>
The	O
SUV	B-Algorithm
can	O
be	O
significantly	O
affected	O
among	O
other	O
things	O
by	O
image	O
noise	O
,	O
low	O
image	O
resolution	O
and/or	O
user	O
biased	O
ROI	O
selection	O
.	O
</s>
<s>
The	O
ratio	O
of	O
the	O
SUV	B-Algorithm
data	O
from	O
two	O
different	O
regions	O
within	O
the	O
same	O
PET	O
image	O
(	O
i.e.	O
</s>
<s>
For	O
the	O
SUVR	O
,	O
the	O
injected	O
activity	O
,	O
the	O
body	O
weight	O
and	O
the	O
mass	O
density	O
that	O
are	O
all	O
part	O
of	O
the	O
SUV	B-Algorithm
calculation	O
,	O
cancel	O
:	O
</s>
<s>
As	O
of	O
2007	O
,	O
the	O
SUV	B-Algorithm
concept	O
had	O
only	O
begun	O
to	O
be	O
tested	O
for	O
other	O
radiotracers	O
such	O
as	O
fluorothymidine	O
F-18	O
(	O
)	O
and	O
conclusions	O
on	O
its	O
usefulness	O
and	O
robustness	O
in	O
these	O
cases	O
were	O
considered	O
premature	O
then	O
.	O
</s>
<s>
In	O
summary	O
,	O
the	O
SUV	B-Algorithm
is	O
a	O
convenient	O
measure	O
for	O
the	O
comparison	O
of	O
PET	O
images	O
from	O
subjects	O
with	O
different	O
body	O
masses	O
.	O
</s>
