<s>
Contraindications	O
to	O
MRI	O
include	O
most	O
cochlear	O
implants	O
and	O
cardiac	B-Device
pacemakers	I-Device
,	O
shrapnel	O
and	O
metallic	O
foreign	O
bodies	O
in	O
the	O
eyes	O
.	O
</s>
<s>
The	O
MRI	O
environment	O
may	O
cause	O
harm	O
in	O
patients	O
with	O
MR-Unsafe	O
devices	O
such	O
as	O
cochlear	O
implants	O
,	O
aneurysm	O
clips	O
,	O
and	O
many	O
permanent	B-Device
pacemakers	I-Device
.	O
</s>
<s>
Several	O
deaths	O
have	O
been	O
reported	O
in	O
patients	O
with	O
pacemakers	B-Device
who	O
have	O
undergone	O
MRI	O
scanning	O
without	O
appropriate	O
precautions	O
.	O
</s>
<s>
Increasingly	O
,	O
MR-conditional	O
pacemakers	B-Device
are	O
available	O
for	O
selected	O
patients	O
.	O
</s>
<s>
In	O
research	O
settings	O
,	O
structural	O
MRI	O
or	O
functional	O
MRI	O
(	O
fMRI	O
)	O
may	O
be	O
combined	O
with	O
EEG	B-Application
(	O
electroencephalography	B-Application
)	O
under	O
the	O
condition	O
that	O
the	O
EEG	B-Application
equipment	O
is	O
MR-compatible	O
.	O
</s>
<s>
Although	O
EEG	B-Application
equipment	O
(	O
electrodes	O
,	O
amplifiers	O
,	O
and	O
peripherals	O
)	O
are	O
either	O
approved	O
for	O
research	O
or	O
clinical	O
use	O
,	O
the	O
same	O
MR	O
Safe	O
,	O
MR	O
Conditional	O
and	O
MR	O
Unsafe	O
terminology	O
applies	O
.	O
</s>
<s>
As	O
described	O
in	O
the	O
Physics	B-Algorithm
of	I-Algorithm
magnetic	I-Algorithm
resonance	I-Algorithm
imaging	I-Algorithm
article	O
,	O
many	O
MRI	O
scanners	O
rely	O
on	O
cryogenic	O
liquids	O
to	O
enable	O
the	O
superconducting	O
capabilities	O
of	O
the	O
electromagnetic	O
coils	O
within	O
.	O
</s>
<s>
As	O
opposed	O
to	O
many	O
other	O
forms	O
of	O
medical	B-Algorithm
imaging	I-Algorithm
in	I-Algorithm
pregnancy	I-Algorithm
,	O
MRI	O
avoids	O
the	O
use	O
of	O
ionizing	O
radiation	O
,	O
to	O
which	O
the	O
fetus	O
is	O
particularly	O
sensitive	O
.	O
</s>
<s>
Despite	O
these	O
concerns	O
,	O
MRI	O
is	O
rapidly	O
growing	O
in	O
importance	O
as	O
a	O
way	O
of	O
diagnosing	O
and	O
monitoring	O
congenital	O
defects	O
of	O
the	O
fetus	O
because	O
it	O
is	O
able	O
to	O
provide	O
more	O
diagnostic	O
information	O
than	O
ultrasound	B-Application
and	O
it	O
lacks	O
the	O
ionizing	O
radiation	O
of	O
CT	O
.	O
MRI	O
without	O
contrast	O
agents	O
is	O
the	O
imaging	O
mode	O
of	O
choice	O
for	O
pre-surgical	O
,	O
in-utero	O
diagnosis	O
and	O
evaluation	O
of	O
fetal	O
tumors	O
,	O
primarily	O
teratomas	O
,	O
facilitating	O
open	O
fetal	O
surgery	O
,	O
other	O
fetal	O
interventions	O
,	O
and	O
planning	O
for	O
procedures	O
(	O
such	O
as	O
the	O
EXIT	O
procedure	O
)	O
to	O
safely	O
deliver	O
and	O
treat	O
babies	O
whose	O
defects	O
would	O
otherwise	O
be	O
fatal	O
.	O
</s>
<s>
Certain	O
hospitals	O
with	O
Children	O
's	O
wards	O
have	O
decorated	O
scanners	O
for	O
this	O
purpose	O
,	O
such	O
as	O
that	O
at	O
the	O
Boston	O
Children	O
's	O
Hospital	O
,	O
which	O
operates	O
a	O
scanner	O
with	O
a	O
special	O
casing	O
designed	O
to	O
resemble	O
a	O
sandcastle	B-Language
.	O
</s>
<s>
Iodinated	B-Application
contrast	I-Application
medium	I-Application
is	O
routinely	O
used	O
in	O
CT	O
and	O
the	O
main	O
adverse	O
events	O
are	O
anaphylactoid	O
reactions	O
and	O
nephrotoxicity	O
.	O
</s>
<s>
Commonly	O
used	O
MRI	B-Algorithm
contrast	I-Algorithm
agents	I-Algorithm
have	O
a	O
good	O
safety	O
profile	O
,	O
but	O
linear	O
non-ionic	O
agents	O
in	O
particular	O
have	O
been	O
implicated	O
in	O
nephrogenic	O
systemic	O
fibrosis	O
in	O
patients	O
with	O
severely	O
impaired	O
renal	O
function	O
.	O
</s>
<s>
MRI	O
is	O
contraindicated	O
in	O
the	O
presence	O
of	O
MR-unsafe	O
implants	O
,	O
and	O
although	O
these	O
patients	O
may	O
be	O
imaged	O
with	O
CT	O
,	O
beam	O
hardening	O
artefact	O
from	O
metallic	O
devices	O
,	O
such	O
as	O
pacemakers	B-Device
and	O
implantable	O
cardioverter-defibrillators	O
,	O
also	O
may	O
affect	O
image	O
quality	O
.	O
</s>
