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IMAGING OF BREAST IMPLANTS

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									IMAGING OF BREAST
    IMPLANTS
   M.Sklair-Levy, M.D
  Radiology Department
  Sheba Medical Center
          Israel
Imaging the Breasts in Patients with
         Breast Implants

The goal of imaging:

To evaluate breast tissues

To evaluate the implants for
complications
              Background

Breast augmentation has been performed
for more than a century
Different substances have been used:
– Fat from lipomas - 1895 - Czerny
– Paraffin - 1904
– Polyvinyl alcohol plastic sponges - 1940
– Free silicone injections - 1945
            Background

Associated with unacceptably high
complication rates
– Inflammation
– Granuloma formation
– Necrosis
– Hardening and deformity of the breast
– Migration of the implanted
  materials,embolization and death.
         Background
1962 - The Cronin implant - the
modern silicone gel-filled implant

– Outer silicone elastomer
  membrane - shell

– Filled with silicone gel
             Background

In 1992 the FDA limited the use of
silicone implants
– Concern about the safety of silicone
  implants
Only saline-filled implants have been
available for cosmetic augmentation
             Background

Current scientific data does not
demonstrate an association between
breast implants and various diseases
The greatest concern was that implants may
stimulate
 – Autoimmune reactions
 – Rheumatoid syndromes
             Introduction

FDA recommended removal of ruptured
implants

Led to the demand for accurate diagnosis
– Clinical diagnosis ; breast size or consistency
– misses 50% of ruptures Implant


Accurate diagnostic imaging
             Introduction
Since 1962 - estimated 1.5 to 2 million
women have had placement of breast
implants

– 80% - placed for breast augmentation

– 20% - for breast reconstruction following
 mastectomy
        Types of Implants

There are numerous types of implants
         More than 200 different types


The most common types:
    Single-lumen saline
    Single-lumen silicone
    Double-lumen implants
 Single-Lumen Saline Implants
Outer silicone envelope filled with saline
– Various valves in the envelope for filling or
  positioning
    may be palpable and mistaken for a mass
    may also be evident by mammography


The type most frequently implanted today
in the USA
 Single-Lumen Saline Implants
Disadvantages

 Less optimal cosmetic result than does
 silicone gel

 More prone to rupture with minor trauma
  – the saline is almost always rapidly resorbed
Single-Lumen Saline Implants
Double-lumen Implants
Double-Lumen (Bilumen) Implants

Inner silicone gel compartment
Outer saline compartment
Silicone elastomer membrane surrounds
each compartment
– fill valve
– degree of filling varies
Reverse double-lumen Implants
 Double-lumen expander implants (Becker
 implants)
 – Inner saline compartment
 – Outer silicone gel compartment
 Silicone elastomer membrane surrounds
 each compartment
 Most often used for breast reconstruction
 after mastectomy
 – Size adjustability
IMAGING
     Mammography


Conventional MLO , CC views

Implant displacement views

 Spot-compression and magnification
views are possible
    Conventional Mammography


Standard views - MLO and CC
– the implants in the field of view
– compression sufficient to hold the breast

Rupture of implants during mammography
is rare but has been reported
Mammography
             Mammography

Implant displacement views - MLO, CC

– Improve the ability to image the breast tissues

    Displacing the implant back against the
    chest wall
    Breast tissues pulled forward as with a
    normal mammogram
     – Direct compression applied separating
       overlapping structures
  Positioning of the implants

The implantation site
– subglandular


– retropectoral
          Subglandular Position

Mainly in the
past
– The implant
  is placed
  behind the
  breast
  tissue
– In front of
  the
  pectoralis
  major
  muscle
   Subpectoral Placement
Behind the pectoralis major muscle
Mammography – Type of Implant


The type of implant can usually be
determined

Possible to distinguish between saline and
silicone gel single-lumen implants
          Mammography - Type of Implant




                       double-
single-lumen           lumen
silicone gel implant   implant   single-lumen
                                 saline implant
Mammography of Intact Implants

Bulges, irregularities, in the outer contour
of silicone implants are nonspecific
– Likely due to pressure deformity from the
  surrounding tissues
– Incomplete fibrous encapsulation


Herniation - protrusion of the implant through
opening in the fibrous capsule
     Capsular Calcifications
Focal or diffuse calcifications may be seen along
the surface of the implant

Tend to increase with the age of the implant
– probably due to microscopic gel bleed through the
  capsule


Do not indicate rupture of the implant
No clinical significance
Capsular Calcifications
Complications of Breast Implants
As expected with other surgical procedure
in which a prosthetic device is implanted

– Acute

– Late
      Acute Complications
Bleeding and infection
Asymmetry
Loss of nipple sensation
Pain and tenderness
      Acute Complications
Asymmetry - implants can be asymmetric
in size, shape, or position.
– Advantage of saline and double-lumen
  implants is that the size can be adjusted


Loss of Nipple Sensation
– Occurs most frequently with the periareolar
  approach
     Late - Complications
Capsular contracture
Rupture (intracapsular or extracapsular)
Migration
Herniation
Hematoma/seroma
Infection
      Capsular Contracture
Most common complication
– Occurs in 10%
– Capsule formation begins within weeks of
  implantation
    All implants become encapsulated by
    fibrous tissue
      – A response to foreign body

– Contraction can occur weeks to years after
  implantation
     Capsular Contracture
The exact cause of capsular contracture is
uncertain
– Gel bleed - silicone gel leakage through
  microperforations in an intact implant
  envelope

    Stimulate production of collagen around the
    implant

    Leading to fibrous capsule formation and
    capsular contracture
            Implant Rupture

The second most common complication
Loss of integrity of the implant envelope/shell

– Most implants show some evidence of implant
  leakage after 15 years


Spectrum of ruptures ranging from microscopic
rents to complete collapse of the implant
              Incidence

The absolute incidence and prevalence of
implant rupture is not known

The reported incidence varies

– 5% -10% - initial studies - in asymptomatic
  patients based on clinical and mammography

– 34% - MRI studies
               Symptoms
Symptoms - depending on the type of implant

Ruptured saline implants deflate rapidly

Rupture of single-lumen silicone gel implants or
of double-lumen implants - more difficult to
evaluate
   Single-Lumen Saline Implant


Complete collapse of the implant and its capsule
almost immediately after rupture
 – Marked asymmetry of the breasts

Diagnostic imaging - unnecessary
– Clinical findings enough
– Imaging to rule out breast pathology
Single Lumen Saline Implant Rupture
           Saline Implant Rupture




Intact saline implant    Collapsed saline implant
    Silicone Gel Implant Rupture


Intracapsular rupture – most common
    Rupture of the shell , silicone gel that leaks out of
    the implant remains confined within the periimplant
    fibrous capsule


Extracapsular rupture - implant envelope
rupture with silicone gel extruded outside
of the fibrous capsule
Implants Shell / Fibrous Capsule
                Symptoms

The clinical findings - difficult to evaluate
– can be clinically inapparent


The implant can remain almost fully expanded
– even in complete collapse
– the outer contour of the periimplant capsule can
  remain normal
– the breast size will appear normal
Mammography of Silicone Gel Implant
           Rupture
Extracapsular rupture
 Irregular collections of free silicone outside
 the implant – unusual

  Silicone in axillary lymph nodes

  Contour abnormalities – more common -
  may be misleading
       cannot be differentiated from herniation
Implant Bulge
Extracapsular rupture
Mammography - Intracapsular Rupture
            Low Sensitivity
   Imaging After Explantation
Residual silicone

Residual fibrous capsule and calcifications

– Explantation through a capsulotomy

– Capsulectomy in addition to explantation
         Imaging After Explantation




Residual fibrous           Residual silicone
capsule
ULTRASOUND
              Technique
The same supine or oblique position

Linear transducer - 7- 12-MHz

Large implants or severe contracture - 5-MHz
linear or even curved linear transducers

Light compression during scanning
Echogenicity of Implant Contents
    Intact silicone & saline implants are
                   anechoic
          Reverberation Artifact

Reverberation echoes
in the near field
    not uncommon


Must be distinguished
from the echogenicity

Light compression-
minimize reverberation
echoes
Reverberation Artifacts
             Radial Folds
Normal variants
– May be palpable – when occur on the anterior
  surface

– Dynamic - not fixed in position and size
Radial Fold
       Implant Fill Valves

Saline implants, expanders, and certain
double-lumen implants have fill valves


– can be palpable
Fill Valve - Single-Lumen Saline
              Implant
Periimplant Effusions
             Implantation Site




Subglandular implant   Retropectoral implant
US of Implant Rupture
      Extracapsular Rupture

Snow storm appearance - The classic
sonographic description of extravasated
silicone

– Homogeneous hyperechoic noise/nodule

– Posterior shadowing
Snowstorm Appearance
         Extracapsular Silicone

There is a spectrum of sonographic
appearances of silicone granulomas
– size

– chronicity

Final diagnosis - biopsy
Complex Cystic Nodules
 Acute Extravasation
            Isoechoic Nodule
Silicone Granulomas of Intermediate Age
  Acoustic Shadowing
Old Silicone Granulomas
    Silicone in Lymph Nodes


May be associated with extracapsular
rupture

Appear hyperechoic
– beginning in the hilum
– progressing to the cortex
     snowstorm shadowing
Silicone in Lymph Nodes
       Intracapsular Rupture

Stepladder Sign - multiple folds of the
collapsed implant shell floating within a
extravasated silicone gel

– Occurs in large rupture with complete or
  nearly complete collapse
Stepladder Sign
Ultrasound & Intracapsular rupture


There is a spectrum of intracapsular
rupture that varies:
 – size of rupture

 – the degree of collapse
         Increased Echogenicity




Intracapsular rupture         Intact implant
 Separation between the Capsule and Shell




 Intact implant          Intracapsular rupture
3 echogenic lines          1 echogenic line
US of Double-Lumen Implants Rupture

More difficult to evaluate rupture
Extracapsular rupture of outer saline shell
 – may simulate single-lumen silicone gel
    implants
Intracapsular rupture - mixing of saline and
silicone gel components
 – a mottling of echogenicity, simulating
    intracapsular rupture of single-lumen silicone
    gel implants
MRI
                 Technique
MRI exams - 1.5T
In prone position
Phased-array breast surface coil
Scan parameters
– High-resolution T2-weighted water/silicone
  suppressed
– T1W fat suppressed
No I.V. contrast
Total scan time - 45min.
  MR Appearance of Normal Implants


The location - subpectoral or subglandular
              Radial Folds

Radial folds - infoldings of redundant envelope

– Low signal intensity linear bands extending
  from the periphery of the implant into the gel
  or saline as undulations of the implant
  contour
Radial Folds
Complex Radial Folds - Long Curved
     MRI of Ruptured Implant


Intracapsular rupture

Extracapsular rupture
           Intracapsular Rupture

Linguine sign- Ruptured envelope
floating within the silicone gel


–   Sensitivity - 76% to 94%
–   Specificity - 97% to 100%
–   Accuracy - 92%
–   PPV - 99% ;       NPV - 79%
Linguine Sign
            Intracapsular Rupture




                            Linguine sign-
Intracapsular rupture       complete collapse
   Subcapsular Line
local shell displacement
Keyhole Sign - silicone within a short radial
                    fold




                         Subcapsular line
Mottled Appearance
       Extracapsular Rupture


The fibrous capsule and the shell are both
ruptured

Diagnosis - silicone outside of the fibrous
capsule
– breast parenchyma
– Axillary lymph nodes
Extracapsular Rupture
             Extracapsular Rupture




                           Silicon in axillary lymph
Intra &extra rupture       nodes
Extracapsular Rupture
Extracapsular rupture; intracapsular rupture not seen
  MRI - Double Lumen Implants

Can be difficult to evaluate,especially
when implant type is unknown
   MRI - Double Lumen Implants


Extracapsular rupture - leak of the water
from the outer compartment
– Can completely mimic an intact single lumen
  silicon implant


Intracapsular rupture - rupture of the inner
membrane –
– Mixing of water and gel
Reverse Double Lumen- Becker expender




    saline
                              saline
  Implants and Breast Cancer
There is no evidence that implants cause
breast cancer
– Breast implants interfere with performance
  and interpretation of screening mammography
– Delayed detection of breast cancer


US , MRI can be useful
– Contrast enhanced sequence added
                 Summary
Mammography - extracapsular rupture
– Insensitive for intracapsular rupture
Ultrasound – extracapsular rupture
– Intracapsular rupture


MRI
– Advantages - Sensitivity 94% ; Specificity
  97%
– Disadvantage - most expensive, less
  available
         Capsular Calcifications

Focal or diffuse calcifications may be seen along
the surface of the implant

Tend to increase with the age of the implant
– probably due to microscopic gel bleed through the
  capsule


Do not indicate rupture of the implant
No clinical significance
Capsular Calcifications
         Acute Complications
Bleeding and Infection

 The risk for bleeding and infection is
 similar to the risks of any surgery

 Infection occurring in the acute phase may
 persist until the implant is removed
        Acute Complications
Asymmetry - implants can be asymmetric
in size, shape, or position.
– Advantage of saline and double-lumen
  implants is that the size can be adjusted


Loss of Nipple Sensation
– Occurs most frequently with the periareolar
  approach
          Capsular Contracture

Most common complication
– Occurs in 10%
– Capsule formation begins within weeks of
  implantation
    All implants become encapsulated by fibrous
    tissue
      – A response to foreign body

– Contraction can occur weeks to years after
  implantation
         Capsular Contracture

The exact cause of capsular contracture is
uncertain
– Gel bleed - silicone gel leakage through
  microperforations in an intact implant
  envelope

    Stimulate production of collagen around the
    implant

    Leading to fibrous capsule formation and
    capsular contracture
                             The Baker Score


 • A standardized scoring system
 • Clinically evaluates the breast’s
   appearance, texture, and tenderness
 • 4 grades of severity, ranging from
   normal to deformed

• American Society of Plastic Surgeons: Silicone breast implant surgery.
www.plasticsurgery.org/public_education/silicone-breast-implant-surgery.cfm
• Holmes JD: Capsular contracture after breast reconstruction with tissue expansion. Br J Plast Surg 1989
• O’Toole M, Caskey CI: Imaging spectrum of breast implant complications: mammography, ultrasound, and
magnetic resonance imaging. Semin Ultrasound CT MR 2000
                  Treatment

  Implant – various textures, shapes, and
  locations
   – Changing the site of implantation from sub-
     glandular to retropectoral
  Saline implants
  Double - lumen implants
  Closed or open capsulotomy
• Capsule removal
• Implant revision and replacement
     US & Capsular Contraction


The diagnosis is made clinically
The sonographic findings include
– Abnormal spherical shape
– The capsule is thickened > 1.5 mm

– The number of radial folds increases
    redundancy of the shell
          Capsular Contraction




Normal implant
                        Contracted spherical
                        implant
      Capsular Contraction



1mm                     3.5mm
   Single-Lumen Saline Implants

Disadvantages

 Less optimal cosmetic result than does
 silicone gel

 More prone to rupture with minor trauma
  – the saline is almost always rapidly resorbed
Single-Lumen Saline Implants
      Acute Complications
Bleeding and infection
Asymmetry
Loss of nipple sensation
Pain and tenderness
Diagnosis of Implant Rupture

        Mammography

          Ultrasound

             MRI
 Mammography & Implant Rupture

The sensitivity depends upon:

– Type of implant – saline , silicone gel implant

– Type of rupture – intracapsular , extracapsular
 Single Lumen Saline Implant Rupture

Rupture of single lumen saline implants is
usually both clinically and
mammographically obvious
               Technique

The same supine or oblique position

Linear transducer - 7- 12-MHz

Large implants or severe contracture - 5-MHz
linear or even curved linear transducers

Light compression during scanning
              Radial Folds

Normal variants
– May be palpable – when occur on the anterior
  surface

– Dynamic - not fixed in position and size
Radial Fold
          Implant Fill Valves

Saline implants, expanders, and certain
double-lumen implants have fill valves


– can be palpable
Fill Valve - Single-Lumen Saline Implant
                MRI Protocol

– Axial T1-weighted GRE
  localizer


– Sagital / Axial T2 W-
  FSE water-
  suppressed



– Axial/Sag T1W
  silicon suppressed
             Mammography

Breast cancer detection - sensitivity is
reduced

– Radiopaque - obscuring large volumes of
  breast tissue



Evaluation of implant integrity
   Mammography - Implant Location

Seen on MLO views
 – sometimes possible on CC views
 Complications of Breast Implants

As expected with other surgical procedure
in which a prosthetic device is implanted

– Acute

– Late
      Late - Complications
Capsular contracture
Rupture (intracapsular or extracapsular)
Migration
Herniation
Hematoma/seroma
Infection
    Mammography of Intact Implants



Bulges, irregularities, in the outer contour
of silicone implants are nonspecific
– Likely due to pressure deformity from the
  surrounding tissues
– Incomplete fibrous encapsulation


Herniation - protrusion of the implant through
opening in the fibrous capsule
               Implant Type

Difference in the speed of sound –
– Slower through silicone gel - 997 m/s
– Soft tissues - 1,540 m/s through
In silicone implants - there will be a step-off in
the chest wall at the edge of the implant
– the chest wall will appear deeper behind the implant


In saline implants - there is no step-off in the
chest wall
US of Silicone & Saline Implants



      Silicon
      implant                     Saline
                                  implant
      Chest wall-
      step off
                          Chest wall



                    No step off
Periimplant Effusions
             Implantation Site




Subglandular implant   Retropectoral implant
US of Complications
              Capsule – Shell Complex

1. Outer surface of capsule
                                            capsule
2. Middle line –merged echo of
   inner surface capsule and
   outer surface of shell;
                                                 shell
    • the space between - the
      thickness of the capsule


3. Posterior line-inner surface
   of the shell                   silicon
          Intracapsular Rupture
Subcapsular Line - local shell displacement

Teardrop or keyhole sign - silicone within a
short radial fold
– Lees sensitive
– Sensitivity increases if seen in more than one
  picture and in two planes

Mottled appearance of the silicone within the
implant
Double Lumen Implant
Reverse Double Lumen - Becker Expender
Reverse Double Lumen
      US of Implant Rupture

Silicone gel single lumen implants

Complex implants

           – Intracapsular rupture

           – Extracapsular rupture
             Reverberation Artifact


Reverberation echoes in
the near field
      not uncommon

Must be distinguished
from the echogenicity


Light compression-
minimize reverberation
echoes
Reverberation Artifacts
     Imaging of Breast Implants

Implants composed of :
  Inner compartment – silicone , saline
  Outer membrane –
  – Shell (silicone elastomer membrane) – part of
    the implant
  – Fibrous Capsule – not part of the implant
       is the body’s response to the implant

								
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