Because of its soft-tissue contrast and the ability to suppress signal, noncontrast MR is the imaging modality of choice to evaluate the integrity of breast implants and related complications.

The latest edition (fifth edition) of the Breast Imaging Reporting and Data System (BI-RADS) provides a systematic outline for the evaluation of breast implants with MR and includes descriptions of implant materials and lumen types, implant locations, abnormal implant contours, peri-implant fluid, intracapsular findings, water droplets, and extracapsular silicone. 

There are different types, styles, and sizes of breast implants, including round or circular and shaped or teardrop implants. In addition to its type, an implant can also be categorized as a single-lumen or double-lumen implant. The single-lumen implant can be filled with liquid silicone gel, cohesive gel, or saline solution. The most common implants are single lumen silicone implants. Double-lumen implants have an external lumen of saline and an internal lumen of silicone solution. Reverse double-lumen implants have an interior saline lumen and an exterior silicone lumen (Figure 1).  

Breast MR to evaluate for implant integrity does not require intravenous contrast material. Recommended sequences are a T2-weighted fast spin-echo sequence with a short inversion-recovery time, a water-suppression sequence (silicone hyperintense and water hypointense) it is called silione only and a silicone-suppression sequence (silicone hypointense and water hyperintense). 

Peri-implant collections are common and are seen in 48% of patients with breast implants. Seromas occurring a year or more after placement of implants are considered late seromas and are rare. They can be secondary to trauma, hematoma (Figure 2), infection, implant rupture, synovial metaplasia, cancer, or BIA-ALCL.

BIA-ALCL is a rare T-cell lymphoma with a delayed manifestation. Patients usually present approximately 10 years after implantation; however, a new effusion that arises more than 1 year after implantation should raise suspicion for BIA-ALCL. The pathogenesis is yet unknown. Patients present with breast swelling, pain, palpable masses, asymmetry, or lymphadenopathy. Systemic symptoms of BIA-ALCL are rare. The initial workup for BIA-ALCL is US (Figure 3). When BIA-ALCL is suspected, breast MR with intravenous contrast material is indicated to evaluate the peri-implant fluid, peri-implant masses, and capsular enhancement. The most common imaging finding is peri-implant fluid, followed by a soft-tissue mass (Figure 4). The current recommendation for a delayed peri-implant fluid collection is image guided pathologic analysis with flow cytometry. 

MR is the diagnostic test of choice to evaluate for implant rupture. Implant rupture can be intracapsular or extracapsular, with intracapsular ruptures representing most cases of implant rupture. Intracapsular rupture occurs when free silicone emerges from a tear in the elastomer shell but the fibrous capsule remains intact, whereas extracapsular rupture occurs when the free silicone enters the surrounding mammary parenchyma secondary to a breakdown of the fibrous capsule. The linguine sign, in which low-signal-intensity curve lines inside the silicone represent collapsed elastomer floating inside the silicone and contained by the fibrous capsule, is the most sensitive and specific sign of intracapsular rupture. Furthermore, the most reliable sign to diagnose extracapsular rupture is the presence of free silicone in the breast parenchyma or the axillary lymph nodes in the presence of intracapsular rupture (Figure 5). 

MG has low sensitivity for detection of implant ruptures, it is useful for the evaluation of the adjacent mammary tissue. Free silicone breast injections, is an alternative form of breast augmentation, although it has serious adverse effects and is banned in many countries. In MG we can see massive densities in both breasts as a result of silicone intraglandular injections (Figure 6). 

US is the first image that should be performed for the evaluation of the implant. The US evaluation of breast implants includes the revision of the regularity of the implant margins, the capsule, its content and homogeneity of the lumen, the presence or not of periprosthetic liquid, free silicone or granulomas in the breast or axilla.

In an intracapsular rupture, an irregular morphology with loss of continuity of the implant is observed in the US, with internal undulating echogenic lines that represent parts of the envelope floating inside the silicone and mobile echogenic silicone between the envelope and the capsule of the implant (Figure 7 and 8).  

In an extracapsular rupture, signs of intracapsular rupture and the association of echogenic intramammary or axillary masses with loss of posterior detail or echogenic posterior noise are observed, known as “snowstorm” image. The “snowstorm” sign has a sensitivity of 85.7% and a specificity of 100% (Figure 9). 

US can also serve as a guide to carry out diagnostic or interventional procedures (Figure 3).

Also on CT sometimes complications can be seen. An intact implant has a homogeneous grey internal density on CT with a surrounding more hyperdens envelope and capsule. On CT different types of fill valves of breast implants can be seen. Capsular calcifications are frequently seen and sometimes the Linguine sign (Figure 10).

Regarding the use of PET-CT associated with the diagnosis of prosthetic complications, its main use is for local and distant staging of the BIA-ALCL.