IMPLANT MAMMAIRE A ENVELOPPE PERMEABLE AUX RAYONS X

BREAST IMPLANT WITH RADIOLUCENT SHELL

Abrégé anglais

A breast implant includes a shell fashioned from one of a group of materials
which exhibit radiolucency at those x-ray in-
tensities normally encountered for mammographic procedures. The radiolucent
shell may be filled with radiolucent fill material
as previously taught to thereby comprise a fully radiolucent breast implant.
The radiolucent breast implant enhances the use of
mammography in detecting tumors in patients having breast implants to more
effectively diagnose and treat cancer.

Revendications

5
What Is Claimed Is:
1. A breast implant comprised of a shell filled
with a filler, both said shell and filler being each made
of materials which are themselves substantially radiolu-
cent under accepted mammographic protocols and intensi-
ties.
2. The implant of Claim 1 wherein said shell is a
material selected from the group consisting of linear
aliphatic polyether urethane; linear aliphatic polyester
urethane; cyclic aliphatic polyether urethane; cyclic
aliphatic polyester urethane; aromatic polyether
urethane; aromatic polyester urethane; polybutylene;
polypropylene; crosslinked olefinic elastomers; and sty-
rene-ethylene/butylene-styrene block copolymer.
3. In a breast implant comprised of a shell filled
with a fill material, the improvement comprising said
shell being made of a material which is itself substan-
tially radiolucent under accepted mammographic protocols
and intensities.
4. The breast implant of Claim 3 wherein said shell
is a material selected from the group consisting of linear
aliphatic polyether urethane; linear aliphatic polyester
urethane; cyclic aliphatic polyether urethane; cyclic
aliphatic polyester urethane; aromatic polyether ure-
thane; aromatic polyester urethane: polybutylene; poly-
propylene; crosslinked olefinic elastomers; and styrene-
ethylene/butylene-styrene block copolymer.
5. A breast implant comprised of a shell filled
with a filler, both said shell and filler being made of
materials having an effective atomic number of 6.0 within
a range of about ~0.5.

Description

CA 02142996 2002-04-04
,. > ..
BREAST IMPLANT WITH RADIOLUCENT SHELL
Background and Summary of the Invention
Breast prostheses are well known in the art and
generally include a shell or envelope which is filled
with a fluid or gel which desirably is used to enlarge
the female breast yet retain its normal appearance, move-
ment, feel, and other cosmetic characteristics. Until
recently, the predominant breast implant had been a sili-
cone envelope filled with a silicone gel. However, re-
cent health concerns have prompted the withdrawal of this
implant from the market. These concerns generally relate
to the health risks caused by migration of the silicone
gel from within the shell, breakage of the shell, or
other introduction of the silicone gel into the~body.
The assignee of the present invention also holds
certain rights under U.S. Patent No. 4,995,882, which
discloses and claims a breast implant comprised of a
silicone shell filled with a radiolucent fill material
such as peanut oil, sunflower seed oil, or any other
suitable fluid with the same atomic number as breast
tissue, Z=5.9. As explained in greater detail therein,

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2
mammograms typically are performed by compressing a
breast between two plates which flattens the breast and
enables a more uniform exposure. A controlled intensity
of x-rays are then passed through the breast for a care-
fully controlled time period to image any artifacts in-
dicative of cancer. As is well known in the art of mam-
mography, great care is taken to minimize the amount of
x-ray energy used as studies have shown that certain
levels of x-ray exposure will itself increase the risk of
developing cancer. Typically, mammographies are conduct-
ed at low x-ray energy levels, such as between the range
of 25-60 kVp. Hence, this prior patent discloses a use-
ful and valuable invention of utilizing a fill material
which is radiolucent using standard mammographic proce-
dures and protocols, and perhaps more importantly, x-ray
intensities.
The inventors herein are also aware of U.S. Patent
No. 4,863,470 which discloses a standard breast implant
comprised of a silicone shell with a silicone gel fill
material. As previously mentioned herein, this breast
implant construction is well known in the prior art and,
up until recently, had been the most popular implant
used. in addition, this patent discloses an identifica-
tion marker or tab which is made from silicone with bis-
muth trioxide or barium sulfate, both of which are much
more "radiopaque°' than the silicone used for the standard
shell or fill material. Hence, presuming an increased x-
ray intensity which would render the standard silicone
breast implant radiolucent, a marker or tab would remain
opaque and thusly visible. This patent also describes a
technique used to read this radiopaque marker which is
more similar to a chest x-ray than to a mammogram. As
taught therein, the patient lies on her back and the x- ,
rays are directed through her breast and chest cavity.
For chest x-rays, energy levels at 125 kVp are common.
The intensity of x-rays required for this procedure sub-

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WO 94/07434 ~ ' ' ~ ~ PCT/US93/07384
3
stantially exceeds that carefully controlled and timed
dosage which is used for mammographic procedures. There-
fore, while this patent suggests that a standard silicone
gel and silicone fill material may be radiolucent, it is
in reality radiopaque for standard mammographic proce-
dures. This deficiency with this prior art implant con-
struction was recognized and dramatically improved upon
with the breast implant with radiolucent fill disclosed
and claimed in prior U.S. Patent 4,995,882.
As an enhancement to the breast implant with
silicone shell and radiolucent fill, the inventors herein
have succeeded in developing a breast implant With a
shell which is also radiolucent. Therefore, with this
breast implant, not only is the fill material comprised
of a radiolucent material, but the shell also is radiolu-
cent itself, using the standards for fudging radiolucency
as explained in prior U.S. Patent 4,995,882, i.e. using
standard mammographic protocols, procedures, and intensi-
ties. The material which the inventors have identified
and are contemplating for use for the shell include any
,, one or more of the following: linear aliphatic polyether
urethane; linear aliphatic polyester urethane; cyclic
aliphatic polyether urethane; cyclic aliphatic polyester
urethane; aromatic polyether urethane; aromatic polyester
urethane; polybutylene; polypropylene; crosslinked ole-
finic elastomers; and styrene-ethylene/butylene-styrene
block copolymer. All of these materials have an effec-
tive atomic number of 6.0 within a range of 0.5, and
therefore exhibit the effective atomic number of fat
which is the mayor component of a human breast. Thus,
with the present invention, a breast implant is disclosed
which includes a radiolucent shell filled with a radiolu-
cent fill material thereby rendering the entire implant
optimally radiolucent for mammographic procedures.

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4'
4
It is not believed that a drawing is required or
even helpful in understanding the present invention and,
hence, none is being submitted.
Detailed Description of the Preferred Embodiment '
The inventors' preferred embodiment for achieving
a breast implant shell which is essentially radiolucent
using standard mammographic procedures, protocols, and
intensities. The inventors believe that materials having
an effective atomic number of 6.0 within a range of t0.5
satisfy this criteria. As examples thereof, the present
invention includes fashioning the shell from any one of a
number of materials such as: linear aliphatic polyether
urethane; linear aliphatic polyester urethane; cyclic
aliphatic polyether urethane; cyclic aliphatic polyester
urethane; aromatic polyether urethane; aromatic polyester
urethane; polybutylene; polypropylene; crosslinked ole-
finic elastomers; and styrene-ethylene/butylene-styrene
block copolymer. It is anticipated that standard manu-
facturing techniques well known to those of ordinary
skill in the art for producing breast implants will be
similarly used with the materials of the present inven-
tion. In other words, it is not anticipated that there
will be any difficulty encountered by those of ordinary
skill in the art in making breast implant shells with the
materials suggested herein as radiolucent.
There are various changes and modifications which
may be made to the invention as would be apparent to
those skilled in the art. However, these changes or
modifications are included in the teaching of the disclo-
sure, and it is intended that the invention be limited
only by the scope of the claims appended hereto.