<s>
Magnetization	B-Algorithm
transfer	I-Algorithm
(	O
MT	O
)	O
,	O
in	O
NMR	O
and	O
MRI	B-Algorithm
,	O
refers	O
to	O
the	O
transfer	O
of	O
nuclear	O
spin	B-General_Concept
polarization	I-General_Concept
and/or	O
spin	O
coherence	O
from	O
one	O
population	O
of	O
nuclei	O
to	O
another	O
population	O
of	O
nuclei	O
,	O
and	O
to	O
techniques	O
that	O
make	O
use	O
of	O
these	O
phenomena	O
.	O
</s>
<s>
There	O
is	O
some	O
ambiguity	O
regarding	O
the	O
precise	O
definition	O
of	O
magnetization	B-Algorithm
transfer	I-Algorithm
,	O
however	O
the	O
general	O
definition	O
given	O
above	O
encompasses	O
all	O
more	O
specific	O
notions	O
.	O
</s>
<s>
The	O
mechanisms	O
of	O
nuclear-spin	O
energy-coupling	O
have	O
been	O
extensively	O
characterized	O
and	O
are	O
described	O
in	O
the	O
following	O
articles	O
:	O
Angular	O
momentum	O
coupling	O
,	O
Magnetic	O
dipole	O
–	O
dipole	O
interaction	O
,	O
J-coupling	O
,	O
Residual	O
dipolar	O
coupling	O
,	O
Nuclear	O
Overhauser	O
effect	O
,	O
Spin	B-Algorithm
–	I-Algorithm
spin	I-Algorithm
relaxation	I-Algorithm
,	O
and	O
Spin	O
saturation	O
transfer	O
.	O
</s>
<s>
A	O
more	O
specific	O
example	O
of	O
this	O
case	O
is	O
presented	O
in	O
the	O
section	O
Chemical	O
Exchange	O
Magnetization	B-Algorithm
transfer	I-Algorithm
.	O
</s>
<s>
In	O
either	O
case	O
,	O
magnetization	B-Algorithm
transfer	I-Algorithm
techniques	O
probe	O
the	O
dynamic	O
relationship	O
between	O
two	O
or	O
more	O
distinguishable	O
nuclei	O
populations	O
,	O
in	O
so	O
far	O
as	O
energy	O
exchange	O
between	O
the	O
populations	O
can	O
be	O
induced	O
and	O
measured	O
in	O
an	O
idealized	O
NMR	O
experiment	O
.	O
</s>
<s>
Because	O
the	O
T2	O
values	O
are	O
so	O
short	O
,	O
the	O
NMR	O
signal	O
from	O
the	O
protons	O
of	O
bound	O
water	O
is	O
not	O
typically	O
observed	O
in	O
MRI	B-Algorithm
.	O
</s>
<s>
When	O
a	O
population	O
of	O
spins	O
is	O
saturated	O
,	O
such	O
that	O
the	O
magnitude	O
of	O
the	O
macroscopic	O
magnetization	O
vector	O
approaches	O
zero	O
,	O
there	O
is	O
no	O
remaining	O
spin	B-General_Concept
polarization	I-General_Concept
with	O
which	O
to	O
produce	O
an	O
NMR	O
signal	O
.	O
</s>
<s>
Longitudinal	O
relaxation	O
refers	O
to	O
the	O
return	O
of	O
longitudinal	O
spin	B-General_Concept
polarization	I-General_Concept
,	O
which	O
occurs	O
at	O
a	O
rate	O
described	O
by	O
T1	O
.	O
</s>
<s>
spin	B-General_Concept
polarization	I-General_Concept
)	O
is	O
being	O
transferred	O
from	O
the	O
bulk	O
water	O
to	O
the	O
spin-saturated	O
hydration	O
population	O
,	O
allows	O
one	O
to	O
conceptually	O
unify	O
chemical	O
exchange	O
methods	O
with	O
other	O
techniques	O
that	O
transfer	O
magnetization	O
between	O
nuclei	O
populations	O
.	O
</s>
<s>
An	O
extension	O
of	O
MT	O
,	O
the	O
magnetization	B-Algorithm
transfer	I-Algorithm
ratio	O
(	O
MTR	O
)	O
has	O
been	O
used	O
in	O
neuroradiology	B-Algorithm
to	O
highlight	O
abnormalities	O
in	O
brain	O
structures	O
.	O
</s>
