Breast Implant MRI : Teaching Points
Case Report
Follow up case of subpectoral
silicone implant with no old scans available.
MR findings
Both breasts suggest well defined regular
silicone implants in deep pectoral region with intact capsule. Subtle
heterogeneity of the silicone signal at places is MR flow or interphase related
with no linguine sign positivity to suggest any intra or extracapsular rupture
of silicone. The contour of implant at places is depressed suggesting partial
collapse (more seen in left breast implant anteriorly. Pectoral muscles appear
normal. Both breast show tiny bright foci – possibly cysts with rest normal
with no axillary lymphadenopathy.
Teaching Points by Dr MGK Murthy, Dr GA
Prasad, MR Technologist
Narasimhulu
Breast
implants are categorized by lumen number, filler
type, and surface contour. Breast implants are commonly positioned either deep
to the glandular tissue (retroglandular or subglandular) or deep to the
pectoralis major muscle (retropectoral or subpectoral).
Fibrous tissue develops around the implant
as a normal physiologic response to a foreign body; this process is termed
“encapsulation.” Early postoperative complications are - hematoma and
infection. Late postoperative complications are- capsular contracture, silicone
granuloma formation, and implant rupture.
Capsular
contracture - abnormal constriction of the fibrous
capsule that surrounds the breast implant which can occur anytime after
surgery, but most commonly occurs within the first few postoperative months and
is more frequently observed with smooth-surfaced silicone implants and
subglandular implants. Capsular contracture is predominantly a clinical
diagnosis. Radiographic findings, which are not always present, include a change
in the shape of the implant (i.e., rounding, irregularity, infolding, or
tenting); thickening of the fibrous capsule, which is best shown on ultrasound;
and peri-implant calcifications.
Implant
Rupture- Silicone implant rupture can be - intracapsular or extracapsular with most
common being intracapsular (77–89%). MRI has a high sensitivity (72–94%) and
specificity (85–100%) for the diagnosis of silicone implant rupture. The
hallmark of intracapsular rupture on MRI is the linguine sign, representing
layers of collapsed elastomeric shell floating in silicone gel contained by the
fibrous capsule. Signs of minimally
collapsed intracapsular rupture include the “teardrop sign,” the “keyhole” or
“noose” sign, and the “subcapsular line” sign. These signs represent small
amounts of silicone outside the implant shell but contained within the fibrous
capsule. MR findings of extracapsular rupture include the presence of free
silicone separate from the implant seen as discrete foci of isointense to low
signal intensity on T1 fat-suppressed images and of high signal intensity on
water-suppressed T2- weighted images.
Silicone
granulomas - may enhance similar to breast carcinomas
and may be difficult to distinguish on the basis of imaging criteria alone,
thus requiring biopsy.
Breast Implant MRI : Teaching Points
Reviewed by Sumer Sethi
on
Monday, October 09, 2017
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