echosens FibroScan 502 touch - Indications and Precautions for Use; Intended Use

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FibroScan

FIBROSCAN

502

TOUCH

USER

MANUAL

ΓΠΕΤΕ]

4.

INDICATIONS

AND

PRECAUTIONS

FOR

USE

4.1.

INTENDED

USE

The

FibroScan

and

its

probes

form

an

active,

non-implantable

medical

device

using

ultrasound.

This

device

is

designed

to

be

used

in

a

physician's

office.

The

FibroScan

system

is

designed

to

provide

50

Hz

shear

wave

speed

measurements

and

estimates

of

tissue

stiffness

as

well

as

a

3.5

MHz

ultrasound

coefficient

for

the

Attenuation

Parameter

(CAP:

Controlled

Attenuation

Parameter)

in

internal

structures

of

the

body.

The

FibroScan

device

is

based

on

Vibration-Controlled Transient

Elastography

(VCTE

M).

The

FibroScan

probe

comprises

a

single-element

ultrasound

transducer

mounted

on

the

shaft

of

the

electrodynamic

transducer.

This

transducer

generates

a

transient

vibration,

which

in

turn

generates

an

elastic

shear

wave.

This

wave

propagates

through

the

skin,

the

subcutaneous

tissues,

and

then

the

liver.

During

shear

wave

propagation,

the

ultrasound

transducer

performs

a

series

of

ultrasound

acquisitions

(emission/reception)

to

measure

the

speed

of

shear

wave

propagation

(Vs)

in

m/s.

This

measurement

corresponds

to

the

spatial

and

temporal

average

speed

of

propagation

of

the

shear

wave

through

the

liver

region

of

interest,

which

can

be

approximated

by

a

cylinder

with

a

diameter

of

1

cm

and

a

length

of

4

cm

(corresponding

to

approx.

3

cm’).

Additionally,

assuming

that

the

liver

is

a

pure

elastic,

linear

and

isotropic

medium,

the

device

converts

shear

wave

speed

Vs

into

equivalent

stiffness

E

in

kPa

using

the

equation

E

=

3

xp

x

Vs?

with

p

the

medium

density

assumed

to

be

1000

kg/m*.

The

values

for

shear

wave

speed

and

equivalent

stiffness

(or

Young’s

modulus)

are

relative

indexes

intended

only

for

the

purpose

of

comparison

with

other

measurements

performed

using

FibroScan

devices.

Concomitantly,

the

ultrasound

acquisitions

are

used

to

assess

the

Controlled

Attenuation

Parameter

(CAP).

Ultrasound

attenuation

corresponds

to

the loss

of

energy

as

ultrasound

propagates

through

the

medium.

Due

to

attenuation,

the

intensity

of

emitted

ultrasound

(lo)

decreases

exponentially

with

depth

(z):

Iz

=

lo

x

exp

(-

a(f)

x

z)

where

Iz

is

the

ultrasound

intensity

at

depth

z

and

a

is

the

frequency-

(f)

dependent

attenuation

coefficient.

Ultrasound

attenuation

depends

principally

on

(i)

the

ultrasound frequency,

and

(ii)

the

properties

of

the

medium

of

propagation.

CAP

assesses

the

value

of

a

at

the

frequency

f

=

3.5

MHz

and

is

expressed

in

dB/m.

Absolute

values

for

these

measurements

may

vary

between

measurement

devices

produced

by

different

manufacturers.

E300M017.4

03/2017

-

ECHOSENSTM

AND

FIBROSCAN®

ARE

TRADEMARKS

©

COPYRIGHT

ECHOSENS

-

ALL

RIGHTS

RESERVED

13

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