<s>
Radioisotope	B-Algorithm
renography	I-Algorithm
is	O
a	O
form	O
of	O
medical	B-Application
imaging	I-Application
of	O
the	O
kidneys	O
that	O
uses	O
radiolabelling	O
.	O
</s>
<s>
A	O
renogram	B-Algorithm
,	O
which	O
may	O
also	O
be	O
known	O
as	O
a	O
MAG3	B-Algorithm
scan	I-Algorithm
,	O
allows	O
a	O
nuclear	O
medicine	O
physician	O
or	O
a	O
radiologist	O
to	O
visualize	O
the	O
kidneys	O
and	O
learn	O
more	O
about	O
how	O
they	O
are	O
functioning	O
.	O
</s>
<s>
MAG3	B-Algorithm
is	O
an	O
acronym	O
for	O
mercapto	O
acetyl	O
tri	O
glycine	O
,	O
a	O
compound	O
that	O
is	O
chelated	O
with	O
a	O
radioactive	O
element	O
–	O
technetium-99m	O
.	O
</s>
<s>
The	O
two	O
most	O
common	O
radiolabelled	O
pharmaceutical	O
agents	O
used	O
are	O
99mTc-MAG3	O
(	O
MAG3	B-Algorithm
is	O
also	O
called	O
"	O
mercaptoacetyltriglycine	B-Algorithm
"	O
or	O
"	O
mertiatide	O
"	O
)	O
and	O
99mTc	O
DTPA	O
(	O
diethylenetriaminepentacetate	O
)	O
.	O
</s>
<s>
Processing	O
then	O
involves	O
drawing	O
a	O
region	B-Algorithm
of	I-Algorithm
interest	I-Algorithm
(	O
ROI	O
)	O
around	O
both	O
kidneys	O
,	O
and	O
a	O
computer	O
program	O
produces	O
a	O
graph	O
of	O
radioactivity	O
inside	O
the	O
kidney	O
with	O
time	O
,	O
representing	O
the	O
quantity	O
of	O
tracer	O
,	O
from	O
the	O
number	O
of	O
counts	O
measured	O
inside	O
in	O
each	O
image	O
(	O
representing	O
a	O
different	O
time	O
point	O
)	O
.	O
</s>
<s>
If	O
the	O
kidney	O
is	O
not	O
getting	O
blood	O
for	O
example	O
,	O
it	O
will	O
not	O
be	O
viewed	O
at	O
all	O
,	O
even	O
if	O
it	O
looks	O
structurally	O
normal	O
in	O
medical	B-Application
ultrasonography	I-Application
or	O
magnetic	O
resonance	O
imaging	O
.	O
</s>
<s>
If	O
the	O
kidney	O
is	O
getting	O
blood	O
,	O
but	O
there	O
is	O
an	O
obstruction	O
inferior	O
to	O
the	O
kidney	O
in	O
the	O
bladder	O
or	O
ureters	O
,	O
the	O
radioisotope	O
will	O
not	O
pass	O
beyond	O
the	O
level	O
of	O
the	O
obstruction	O
,	O
whereas	O
if	O
there	O
is	O
a	O
partial	O
obstruction	O
then	O
there	O
is	O
a	O
delayed	O
transit	O
time	O
for	O
the	O
MAG3	B-Algorithm
to	O
pass	O
.	O
</s>
<s>
MAG3	B-Algorithm
is	O
preferred	O
over	O
99mTc	O
DTPA	O
in	O
neonates	O
,	O
patients	O
with	O
impaired	O
function	O
,	O
and	O
patients	O
with	O
suspected	O
obstruction	O
,	O
due	O
to	O
its	O
more	O
efficient	O
extraction	O
.	O
</s>
<s>
The	O
MAG3	B-Algorithm
clearance	O
is	O
highly	O
correlated	O
with	O
the	O
effective	O
renal	O
plasma	O
flow	O
(	O
ERPF	O
)	O
,	O
and	O
the	O
MAG3	B-Algorithm
clearance	O
can	O
be	O
used	O
as	O
an	O
independent	O
measure	O
of	O
kidney	O
function	O
.	O
</s>
<s>
After	O
intravenous	O
administration	O
,	O
about	O
40-50	O
%	O
of	O
the	O
MAG3	B-Algorithm
in	O
the	O
blood	O
is	O
extracted	O
by	O
the	O
proximal	O
tubules	O
with	O
each	O
pass	O
through	O
the	O
kidneys	O
;	O
the	O
proximal	O
tubules	O
then	O
secrete	O
the	O
MAG3	B-Algorithm
into	O
the	O
tubular	O
lumen	O
.	O
</s>
<s>
The	O
extraction	O
fraction	O
of	O
DTPA	O
is	O
approximately	O
20%	O
,	O
less	O
than	O
half	O
that	O
of	O
MAG3	B-Algorithm
.	O
</s>
<s>
In	O
1986	O
,	O
MAG3	B-Algorithm
was	O
developed	O
at	O
the	O
University	O
of	O
Utah	O
by	O
Dr.	O
Alan	O
R	O
.	O
Fritzberg	O
,	O
Dr.	O
Sudhakar	O
Kasina	O
,	O
and	O
Dr.	O
Dennis	O
Eshima	O
.	O
</s>
<s>
Before	O
the	O
development	O
of	O
tracers	O
such	O
as	O
99mTc-MAG3	O
,	O
a	O
range	O
of	O
other	O
radiopharmaceuticals	O
were	O
employed	O
.	O
</s>
<s>
99mTc-MAG3	O
has	O
replaced	O
131I-OIH	O
because	O
of	O
better	O
quality	O
imaging	O
regardless	O
of	O
the	O
level	O
of	O
kidney	O
function	O
,	O
and	O
lower	O
radiation	O
doses	O
.	O
</s>
