<s>
In	O
magnetic	O
resonance	O
imaging	O
,	O
the	O
flip	B-Algorithm
angle	I-Algorithm
,	O
also	O
called	O
the	O
nutation	O
angle	O
,	O
pulse	O
angle	O
,	O
tip	O
angle	O
,	O
or	O
excitation	O
angle	O
,	O
refers	O
to	O
the	O
angle	O
that	O
the	O
magnetization	O
vector	O
is	O
tipped	O
or	O
rotated	O
away	O
from	O
the	O
z-axis	O
by	O
a	O
radiofrequency	O
pulse	O
,	O
relative	O
to	O
the	O
main	O
magnetic	O
field	O
.	O
</s>
<s>
The	O
flip	B-Algorithm
angle	I-Algorithm
is	O
generally	O
measured	O
in	O
degrees	O
or	O
radians	O
;	O
for	O
example	O
,	O
a	O
90-degree	O
flip	B-Algorithm
angle	I-Algorithm
will	O
deflect	O
all	O
longitudinal	O
magnetization	O
into	O
the	O
transverse	O
,	O
or	O
xy	O
plane	O
.	O
</s>
<s>
Changing	O
the	O
amplitude	O
or	O
duration	O
of	O
the	O
pulse	O
will	O
change	O
the	O
flip	B-Algorithm
angle	I-Algorithm
.	O
</s>
<s>
The	O
Ernst	B-Algorithm
angle	I-Algorithm
,	O
named	O
for	O
Richard	O
R	O
.	O
Ernst	O
who	O
described	O
it	O
,	O
refers	O
to	O
the	O
flip	B-Algorithm
angle	I-Algorithm
that	O
will	O
produce	O
the	O
maximal	O
intensity	O
of	O
a	O
signal	O
for	O
a	O
given	O
T1	O
relaxation	O
time	O
and	O
repetition	O
time	O
.	O
</s>
