<s>
In	O
medical	B-Application
imaging	I-Application
,	O
a	O
time-activity	B-Algorithm
curve	I-Algorithm
is	O
a	O
curve	O
of	O
radioactivity	O
(	O
in	O
terms	O
of	O
concentration	O
)	O
plotted	O
on	O
the	O
y-axis	O
against	O
the	O
time	O
plotted	O
on	O
the	O
x-axis	O
.	O
</s>
<s>
Generally	O
,	O
when	O
a	O
time-activity	B-Algorithm
curve	I-Algorithm
is	O
obtained	O
within	O
a	O
tissue	O
,	O
it	O
is	O
called	O
as	O
a	O
tissue	O
time-activity	B-Algorithm
curve	I-Algorithm
,	O
which	O
represents	O
the	O
concentration	O
of	O
tracer	O
within	O
a	O
region	O
of	O
interest	O
inside	O
a	O
tissue	O
over	O
time	O
.	O
</s>
<s>
Modern	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
a	O
tissue	O
time-activity	B-Algorithm
curve	I-Algorithm
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
positron	B-Application
emission	I-Application
tomography	I-Application
(	O
PET	O
)	O
imaging	O
,	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
using	O
a	O
dynamic	O
scan	O
.	O
</s>
<s>
Each	O
data-point	O
in	O
the	O
time-activity	B-Algorithm
curve	I-Algorithm
represents	O
a	O
measurement	O
of	O
tracer-concentration	O
from	O
the	O
region	O
segmented	O
on	O
each	O
of	O
these	O
image	O
time-frame	O
acquired	O
over	O
time	O
.	O
</s>
<s>
Time-activity	B-Algorithm
curves	I-Algorithm
are	O
obtained	O
with	O
the	O
help	O
of	O
region-of-interest	O
analysis	O
.	O
</s>
<s>
Obtaining	O
the	O
time-activity	B-Algorithm
curve	I-Algorithm
within	O
an	O
artery	O
is	O
the	O
first	O
towards	O
obtaining	O
the	O
image-derived	O
arterial	B-Algorithm
input	I-Algorithm
function	I-Algorithm
(	O
IDAIF	O
)	O
.	O
</s>
<s>
The	O
arterial	O
time-activity	B-Algorithm
curve	I-Algorithm
is	O
then	O
corrected	O
for	O
various	O
errors	O
using	O
arterial/venous	O
blood-sample	O
before	O
an	O
arterial	B-Algorithm
input	I-Algorithm
function	I-Algorithm
(	O
AIF	O
)	O
can	O
be	O
used	O
as	O
an	O
input	O
to	O
the	O
model	O
for	O
kinetic	O
analysis	O
.	O
</s>
