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
single-lumen
silicone gel implant
doublelumen
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
capsule
Residual silicone
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 compressionminimize 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
Intracapsular rupture
Linguine signcomplete 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
Intra &extra rupture
Silicon in axillary lymph
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 subglandular 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 WFSE watersuppressed
– 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 wallstep 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 compressionminimize 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