<s>
Functional	B-Algorithm
imaging	I-Algorithm
(	O
or	O
physiological	O
imaging	O
)	O
is	O
a	O
medical	B-Application
imaging	I-Application
technique	I-Application
of	O
detecting	O
or	O
measuring	O
changes	O
in	O
metabolism	O
,	O
blood	O
flow	O
,	O
regional	O
chemical	O
composition	O
,	O
and	O
absorption	O
.	O
</s>
<s>
As	O
opposed	O
to	O
structural	O
imaging	O
,	O
functional	B-Algorithm
imaging	I-Algorithm
centers	O
on	O
revealing	O
physiological	O
activities	O
within	O
a	O
certain	O
tissue	O
or	O
organ	O
by	O
employing	O
medical	B-Application
image	I-Application
modalities	O
that	O
very	O
often	O
use	O
tracers	O
or	O
probes	O
to	O
reflect	O
spatial	O
distribution	O
of	O
them	O
within	O
the	O
body	O
.	O
</s>
