<s>
Arterial	B-Algorithm
input	I-Algorithm
function	I-Algorithm
(	O
AIF	O
)	O
,	O
also	O
known	O
as	O
a	O
plasma	O
input	O
function	O
,	O
refers	O
to	O
the	O
concentration	O
of	O
tracer	O
in	O
blood-plasma	O
in	O
an	O
artery	O
measured	O
over	O
time	O
.	O
</s>
<s>
in	O
1962	O
to	O
measure	O
the	O
exchange	O
of	O
materials	O
between	O
red	O
blood	O
cells	O
and	O
blood	O
plasma	O
,	O
and	O
by	O
other	O
researchers	O
in	O
1983	O
for	O
positron	B-Application
emission	I-Application
tomography	I-Application
(	O
PET	O
)	O
studies	O
.	O
</s>
<s>
Nowadays	O
,	O
kinetic	O
analysis	O
is	O
performed	O
in	O
various	O
medical	B-Application
imaging	I-Application
techniques	I-Application
,	O
which	O
requires	O
an	O
AIF	O
as	O
one	O
of	O
the	O
inputs	O
to	O
the	O
mathematical	O
model	O
,	O
for	O
example	O
,	O
in	O
dynamic	O
PET	B-Application
imaging	I-Application
,	O
or	O
perfusion	O
CT	O
,	O
or	O
dynamic	O
contrast-enhanced	O
magnetic	O
resonance	O
imaging	O
(	O
DCE-MRI	O
)	O
.	O
</s>
<s>
AIF	O
can	O
be	O
obtained	O
in	O
several	O
different	O
ways	O
,	O
for	O
example	O
,	O
using	O
the	O
invasive	O
method	O
of	O
continuous	O
arterial	O
sampling	O
using	O
an	O
online	O
blood	O
monitor	O
,	O
using	O
the	O
invasive	O
method	O
of	O
arterial	O
blood	O
samples	O
obtained	O
at	O
discrete	O
time	O
points	O
post-injection	O
,	O
using	O
a	O
minimally	O
invasive	O
method	O
using	O
a	O
population-based	O
AIF	O
where	O
an	O
input	O
function	O
in	O
a	O
subject	O
is	O
estimated	O
partly	O
from	O
the	O
prior	O
information	O
obtained	O
from	O
a	O
previous	O
population	O
and	O
partly	O
from	O
the	O
blood	O
information	O
from	O
the	O
subject	O
itself	O
obtained	O
at	O
the	O
time	O
of	O
scanning	O
,	O
or	O
using	O
an	O
image-derived	O
arterial	B-Algorithm
input	I-Algorithm
function	I-Algorithm
(	O
IDAIF	O
)	O
obtained	O
by	O
placing	O
a	O
region	O
of	O
interest	O
(	O
ROI	O
)	O
over	O
an	O
artery	O
and	O
calibrating	O
the	O
resulting	O
curves	O
against	O
venous	O
blood	O
samples	O
obtained	O
during	O
the	O
later	O
phases	O
(	O
30	O
to	O
60	O
minutes	O
)	O
of	O
the	O
dynamic	O
scan	O
when	O
venous	O
and	O
arterial	O
tracer	O
concentrations	O
become	O
equal	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
dynamic	O
PET	B-Application
scan	I-Application
acquired	O
over	O
a	O
period	O
of	O
one	O
hour	O
contains	O
the	O
first	O
few	O
short	O
image	O
frames	O
acquired	O
for	O
5	O
seconds	O
duration	O
to	O
capture	O
the	O
fast	O
dynamics	O
of	O
the	O
tracer	O
immediately	O
after	O
a	O
tracer-injection	O
and	O
later	O
frames	O
acquired	O
for	O
30	O
seconds	O
.	O
</s>
<s>
Another	O
study	O
in	O
head	O
and	O
neck	O
cancer	O
patients	O
imaged	O
using	O
[18F]FLT	O
PET	O
,	O
and	O
numerous	O
other	O
studies	O
,	O
obtained	O
discrete	O
arterial	O
samples	O
for	O
the	O
estimation	O
of	O
arterial	B-Algorithm
input	I-Algorithm
function	I-Algorithm
.	O
</s>
<s>
thoroughly	O
reviewed	O
the	O
literature	O
on	O
the	O
arterial	B-Algorithm
input	I-Algorithm
function	I-Algorithm
used	O
for	O
brain	O
PET	B-Application
imaging	I-Application
and	O
suggested	O
the	O
possibility	O
of	O
population-based	O
arterial	B-Algorithm
input	I-Algorithm
functions	I-Algorithm
as	O
a	O
potential	O
alternative	O
to	O
invasive	O
arterial	O
sampling	O
.	O
</s>
<s>
derived	O
a	O
semi-population	O
based	O
method	O
from	O
healthy	O
postmenopausal	O
women	O
imaged	O
using	O
[18F]NaF	O
for	O
bone	O
studies	O
based	O
on	O
the	O
observation	O
that	O
the	O
later	O
part	O
of	O
the	O
arterial	B-Algorithm
input	I-Algorithm
function	I-Algorithm
can	O
be	O
constructed	O
from	O
the	O
venous	O
blood	O
samples	O
,	O
as	O
the	O
venous	O
and	O
arterial	O
blood	O
concentration	O
of	O
tracer	O
is	O
equal	O
30	O
minutes	O
after	O
the	O
injection	O
.	O
</s>
<s>
When	O
combined	O
,	O
a	O
semi-population	O
based	O
arterial	B-Algorithm
input	I-Algorithm
function	I-Algorithm
is	O
obtained	O
as	O
a	O
result	O
.	O
</s>
<s>
An	O
image-derived	O
arterial	B-Algorithm
input	I-Algorithm
function	I-Algorithm
(	O
IDAIF	O
)	O
obtained	O
by	O
measuring	O
the	O
tracer	O
counts	O
over	O
the	O
aorta	O
,	O
carodit	O
artery	O
,	O
or	O
radial	O
artery	O
offers	O
an	O
alternative	O
to	O
invasive	O
arterial	O
blood	O
sampling	O
.	O
</s>
<s>
The	O
arterial	O
time-activity	B-Algorithm
curve	I-Algorithm
(	O
TAC	O
)	O
from	O
the	O
image	O
data	O
requires	O
corrections	O
for	O
metabolites	O
formed	O
over	O
time	O
,	O
differences	O
between	O
whole	O
blood	O
and	O
plasma	O
activity	O
,	O
which	O
are	O
not	O
constant	O
over	O
time	O
,	O
correction	O
for	O
partial	O
volume	O
errors	O
(	O
PVE	O
)	O
due	O
to	O
the	O
small	O
size	O
of	O
the	O
ROI	O
,	O
spill-over	O
errors	O
due	O
to	O
activity	O
from	O
neighbouring	O
tissues	O
outside	O
the	O
ROI	O
,	O
error	O
due	O
to	O
patient	O
movement	O
,	O
and	O
noise	O
introduced	O
due	O
to	O
the	O
limited	O
number	O
of	O
counts	O
acquired	O
in	O
each	O
image	O
time	O
frame	O
because	O
of	O
the	O
short	O
time	O
frames	O
.	O
</s>
<s>
These	O
errors	O
are	O
corrected	O
using	O
late	O
venous	O
blood	O
samples	O
,	O
and	O
the	O
resulting	O
curve	O
is	O
called	O
an	O
arterial	B-Algorithm
input	I-Algorithm
function	I-Algorithm
(	O
AIF	O
)	O
.	O
</s>
