<s>
High-intensity	B-Architecture
focused	I-Architecture
ultrasound	I-Architecture
(	O
HIFU	B-Architecture
)	O
is	O
a	O
non-invasive	O
therapeutic	O
technique	O
that	O
uses	O
non-ionizing	O
ultrasonic	O
waves	O
to	O
heat	O
or	O
ablate	O
tissue	O
.	O
</s>
<s>
HIFU	B-Architecture
can	O
be	O
used	O
to	O
increase	O
the	O
flow	O
of	O
blood	O
or	O
lymph	O
or	O
to	O
destroy	O
tissue	O
,	O
such	O
as	O
tumors	O
,	O
via	O
thermal	O
and	O
mechanical	O
mechanisms	O
.	O
</s>
<s>
Given	O
the	O
prevalence	O
and	O
relatively	O
low	O
cost	O
of	O
ultrasound	O
generation	O
mechanisms	O
,	O
The	O
premise	O
of	O
HIFU	B-Architecture
is	O
that	O
it	O
is	O
expect	O
a	O
non-invasive	O
and	O
low-cost	O
therapy	O
that	O
can	O
at	O
minimum	O
outperform	O
of	O
care	O
.	O
</s>
<s>
The	O
technology	O
is	O
different	O
from	O
that	O
used	O
in	O
ultrasonic	B-Application
imaging	I-Application
,	O
though	O
lower	O
frequencies	O
and	O
continuous	O
,	O
rather	O
than	O
pulsed	O
,	O
waves	O
are	O
used	O
to	O
achieve	O
the	O
necessary	O
thermal	O
doses	O
.	O
</s>
<s>
HIFU	B-Architecture
is	O
combined	O
with	O
other	O
imaging	B-Application
techniques	I-Application
such	O
as	O
medical	B-Application
ultrasound	I-Application
or	O
MRI	B-Algorithm
to	O
enable	O
guidance	O
of	O
the	O
treatment	O
and	O
monitoring	O
.	O
</s>
<s>
The	O
InsighTec	O
ExAblate	O
2000	O
was	O
the	O
first	O
MRgFUS	B-Architecture
system	O
to	O
obtain	O
FDA	O
market	O
approval	O
.	O
</s>
<s>
There	O
is	O
no	O
clear	O
consensus	O
on	O
the	O
boundaries	O
between	O
HIFU	B-Architecture
and	O
other	O
forms	O
of	O
therapeutic	B-Algorithm
ultrasound	I-Algorithm
.	O
</s>
<s>
In	O
particular	O
literature	O
,	O
HIFU	B-Architecture
refers	O
to	O
the	O
high	O
levels	O
of	O
energy	O
required	O
to	O
destroy	O
tissue	O
through	O
ablation	B-Algorithm
or	O
cavitation	O
,	O
although	O
it	O
is	O
also	O
sometimes	O
used	O
to	O
describe	O
lower	O
intensity	O
applications	O
such	O
as	O
occupational	O
therapy	O
and	O
physical	O
therapy	O
.	O
</s>
<s>
Either	O
way	O
,	O
HIFU	B-Architecture
is	O
used	O
to	O
non-invasively	O
heat	O
tissue	O
deep	O
in	O
the	O
body	O
without	O
the	O
need	O
for	O
an	O
incision	O
.	O
</s>
<s>
One	O
of	O
the	O
first	O
applications	O
of	O
HIFU	B-Architecture
was	O
the	O
treatment	O
of	O
Parkinson	O
's	O
disease	O
in	O
the	O
1940s	O
.	O
</s>
<s>
Although	O
ineffective	O
at	O
the	O
time	O
,	O
HIFU	B-Architecture
has	O
the	O
capacity	O
to	O
lesion	O
pathology	O
.	O
</s>
<s>
A	O
focused	B-Architecture
ultrasound	I-Architecture
system	O
is	O
approved	O
in	O
Israel	O
,	O
Canada	O
,	O
Itaria	O
,	O
Korea	O
and	O
Russia	O
to	O
treat	O
essential	O
tremor	O
,	O
neuropathic	O
pain	O
,	O
and	O
Parkinsonian	O
tremor	O
.	O
</s>
<s>
HIFU	B-Architecture
may	O
be	O
effective	O
for	O
detecting	O
prostate	O
cancer	O
.	O
</s>
<s>
HIFU	B-Architecture
is	O
studied	O
in	O
liver	O
cancer	O
and	O
in	O
many	O
studies	O
report	O
a	O
high	O
response	O
rate	O
and	O
positive	O
outcome	O
.	O
</s>
<s>
During	O
the	O
treatment	O
of	O
metastasized	O
liver	O
cancer	O
with	O
HIFU	B-Architecture
,	O
immune	O
responses	O
have	O
been	O
observed	O
in	O
locations	O
that	O
are	O
distant	O
from	O
the	O
focal	O
region	O
.	O
</s>
<s>
Treatment	O
of	O
prostate	O
enlargement	O
(	O
benign	O
prostatic	O
hyperplasia	O
)	O
by	O
HIFU	B-Architecture
from	O
inside	O
the	O
intestine	O
(	O
transrectal	O
)	O
has	O
turned	O
out	O
to	O
be	O
unsuccessful	O
.	O
</s>
<s>
In	O
some	O
countries	O
,	O
not	O
in	O
USA	O
,	O
HIFU	B-Architecture
has	O
also	O
been	O
offered	O
from	O
the	O
inside	O
of	O
the	O
prostate	O
,	O
that	O
is	O
,	O
via	O
a	O
catheter	O
in	O
the	O
prostatic	O
urethra	O
.	O
</s>
<s>
HIFU	B-Architecture
beams	O
are	O
precisely	O
focused	O
on	O
a	O
small	O
region	O
of	O
diseased	O
tissue	O
to	O
locally	O
deposit	O
high	O
levels	O
of	O
energy	O
.	O
</s>
<s>
Focused	B-Architecture
ultrasound	I-Architecture
may	O
be	O
used	O
to	O
generate	O
highly	O
localized	O
heating	O
to	O
treat	O
cysts	O
and	O
tumors	O
(	O
benign	O
or	O
malignant	O
)	O
.	O
</s>
<s>
This	O
is	O
known	O
as	O
Magnetic	B-Architecture
Resonance	I-Architecture
guided	I-Architecture
Focused	I-Architecture
Ultrasound	I-Architecture
(	O
MRgFUS	B-Architecture
)	O
or	O
High	B-Architecture
Intensity	I-Architecture
Focused	I-Architecture
Ultrasound	I-Architecture
(	O
HIFU	B-Architecture
)	O
.	O
</s>
<s>
These	O
procedures	O
generally	O
use	O
lower	O
frequencies	O
than	O
medical	O
diagnostic	B-Application
ultrasound	I-Application
(	O
from	O
0.7	O
to	O
2MHz	O
)	O
,	O
but	O
higher	O
the	O
frequency	O
means	O
lower	O
the	O
focusing	O
energy	O
.	O
</s>
<s>
HIFU	B-Architecture
treatment	O
is	O
often	O
guided	O
by	O
MRI	B-Algorithm
.	O
</s>
<s>
Focused	B-Architecture
ultrasound	I-Architecture
may	O
be	O
used	O
to	O
dissolve	O
kidney	O
stones	O
by	O
lithotripsy	O
.	O
</s>
<s>
There	O
are	O
some	O
reports	O
that	O
HIFU	B-Architecture
could	O
be	O
applied	O
to	O
cancers	O
to	O
disrupt	O
the	O
tumor	O
microenvironment	O
and	O
trigger	O
an	O
immune	O
response	O
,	O
as	O
well	O
as	O
possibly	O
enhance	O
the	O
efficacy	O
of	O
immunotherapy	O
.	O
</s>
<s>
There	O
are	O
several	O
ways	O
to	O
focus	O
ultrasound	O
—	O
via	O
a	O
lens	O
(	O
for	O
example	O
,	O
a	O
polystyrene	O
lens.parabola	O
curve	O
transducer	B-Algorithm
,	O
a	O
phased	O
array	O
,	O
etc	O
.	O
</s>
<s>
Geometrically	O
,	O
for	O
example	O
with	O
a	O
lens	O
or	O
with	O
a	O
spherically	O
curved	O
transducer	B-Algorithm
.	O
</s>
<s>
Electronically	O
,	O
by	O
adjusting	O
the	O
relative	O
phases	O
of	O
elements	O
in	O
an	O
array	O
of	O
transducers	B-Algorithm
(	O
a	O
"	O
phased	O
array	O
"	O
)	O
.	O
</s>
<s>
Following	O
ablation	B-Algorithm
a	O
distinct	O
boundary	O
forms	O
between	O
healthy	O
and	O
necrotic	O
tissue	O
(	O
width	O
less	O
than	O
50	O
microns	O
)	O
.	O
</s>
<s>
The	O
most	O
common	O
transducer	B-Algorithm
used	O
is	O
a	O
concave	O
focusing	O
transducer	B-Algorithm
with	O
a	O
fixed	O
aperture	O
and	O
a	O
fixed	O
focal	O
length	O
.	O
</s>
<s>
Phased	O
array	O
transducers	B-Algorithm
can	O
also	O
be	O
used	O
with	O
different	O
arrangements	O
(	O
flat/bowl	O
)	O
.	O
</s>
<s>
HIFU	B-Architecture
therapy	O
requires	O
careful	O
monitoring	O
and	O
so	O
it	O
is	O
usually	O
performed	O
in	O
conjunction	O
with	O
other	O
imaging	B-Application
techniques	I-Application
.	O
</s>
<s>
Pre-operative	O
imaging	O
,	O
for	O
instance	O
CT	O
and	O
MRI	B-Algorithm
,	O
are	O
usually	O
used	O
to	O
identify	O
general	O
parameters	O
of	O
the	O
target	O
anatomy	O
.	O
</s>
<s>
Both	O
MRI	B-Algorithm
and	O
Medical	B-Application
ultrasound	I-Application
imaging	O
have	O
been	O
used	O
for	O
guidance	O
in	O
FUS	O
treatment	O
.	O
</s>
<s>
These	O
techniques	O
are	O
known	O
as	O
Magnetic	B-Architecture
Resonance	I-Architecture
guided	I-Architecture
Focused	I-Architecture
Ultrasound	I-Architecture
Surgery	O
(	O
MRgFUS	B-Architecture
)	O
and	O
Ultrasound	O
guided	O
Focused	B-Architecture
Ultrasound	I-Architecture
Surgery	O
(	O
USgFUS	O
)	O
respectively	O
.	O
</s>
<s>
MRgFUS	B-Architecture
is	O
a	O
3D	O
imaging	O
technique	O
which	O
features	O
high	O
soft	O
tissue	O
contrast	O
and	O
provides	O
information	O
about	O
temperature	O
,	O
thus	O
allowing	O
to	O
monitor	O
ablation	B-Algorithm
.	O
</s>
<s>
The	O
implication	O
of	O
this	O
is	O
that	O
if	O
the	O
target	O
region	O
is	O
not	O
visualized	O
by	O
ultrasound	B-Application
imaging	I-Application
before	O
and	O
during	O
HIFU	B-Architecture
therapy	O
,	O
then	O
it	O
is	O
unlikely	O
that	O
HIFU	B-Architecture
therapy	O
will	O
be	O
effective	O
in	O
that	O
specific	O
region	O
.	O
</s>
