Imaging implants

Implants are used for breast augmentation and for reconstruction following surgery. Magnetic resonance imaging (MRI) is the modality of choice for evaluating such breasts with a higher sensitivity and specificity than mammography or ultrasound for detecting implant rupture and an ability to assess adjacent tissues.

Evaluation is tailored to the clinical setting. Sequences are chosen to differentiate fat, fluid and silicone. Where there is suspicion of malignancy, dynamic contrast enhanced sequences are included.

Indications for imaging include suspected rupture, fluid collections, implant migration or a palpable mass. Implant rupture may be intracapsular or extracapsular. MRI is the most reliable modality for identifying and characterising rupture (sensitivity 95%, specificity 93%). The 'linguine' sign due to the collapsed implant shell has the highest sensitivity. Where there is extracapsular silicone, MRI can document the extent of migration. Examples of normal and abnormal implants will be demonstrated.

There is no evidence that implants result in an increased risk of breast cancer nor of any adverse effect on stage at presentation. Similarly there is no evidence that breast reconstruction delays diagnosis of local recurrence. Contrast enhanced MRI may be the most accurate method for detecting recurrence but there have been no studies to evaluate routine MRI surveillance.