MRI Is Most Accurate Test for Detecting Ruptured Silicone Breast Implants
But Ultrasound Still Plays a Role in Follow-Up After Breast Reconstruction, Reports Plastic and Reconstructive Surgery

PHILADELPHIA — Magnetic resonance imaging (MRI) has higher accuracy than ultrasound in diagnosing ruptured silicone implants after breast reconstruction, reports a study in the July issue of Plastic and Reconstructive Surgery®, the official medical journal of the American Society of Plastic Surgeons (ASPS).

Ultrasound is still the most appropriate test for screening and follow-up for women with implant-based breast reconstruction after mastectomy, according to the report by Dr. Mario Rietjens and colleagues of the European Institute of Oncology, Milan. But the new findings suggest that the plastic surgeon should use MRI to make a definitive diagnosis of implant rupture, before performing repeat breast surgery.

MRI vs Ultrasound for Diagnosis of Breast Implant Rupture

The researchers compared the accuracy of MRI versus ultrasound for detecting ruptured implants. They study included 102 women who had received silicone gel implants for breast reconstruction after mastectomy for breast cancer. A median of five years later, the women were undergoing repeat surgery to change the implant for cosmetic reasons. At that time, none of the patients had symptoms of implant rupture or other problems.

Before surgery, all patients underwent both MRI and ultrasound scanning. The researchers compared the two imaging methods for their ability to detect ruptured silicone implants, as confirmed at repeat surgery.

At surgery, 28 percent of the women were found to have implant rupture. Ruptured implants appeared to be more common five years or longer after breast reconstruction.

Overall, MRI was 94 percent accurate in detecting ruptured implants, compared to 72 percent accuracy for ultrasound. Magnetic resonance imaging also had a lower "false-negative" rate: five percent, compared to nine percent with ultrasound. Thus MRI was less likely to miss a ruptured implant, compared to ultrasound.

However, both tests performed well in correctly indicating when implants weren't ruptured. The "negative predictive value" was 94 percent with MRI and 85 percent with ultrasound.

Implications for Screening and Diagnosis after Breast Reconstruction

Implants are widely used for breast reconstruction after mastectomy. Implant rupture is an important complication, resulting in cosmetic problems and requiring further surgery. The need for additional surgery increases the risk of other problems, such as hardening (contracture) of the capsule around the implant, scarring, and pain.

The true rate of ruptured implants is unknown; they can't be reliably detected based on symptoms or physical examination. Studies of different imaging options for detecting ruptured implants have reported varying results. The new study of women undergoing implant removal for cosmetic reasons provides an opportunity to compare MRI versus ultrasound for detection of ruptured implants.

"Our results show that MRI performs better than ultrasound for diagnosis of breast implant rupture, " Dr. Rietjens and coauthors write. They identify some MRI findings specifically associated with the presence of ruptured implants, and suggest that accuracy may be further increased by standardizing MRI criteria.

Where available, MRI should be regarded as the preferred imaging test for women with suspected implant rupture, according to the authors. However, if MRI is unavailable or can't be used, ultrasound is a useful alternative.

However, because of the higher cost of MRI, ultrasound is preferable as a routine follow-up test after implant-based breast reconstruction in women who are free of any symptoms, Dr. Rietjens and colleagues believe. If ultrasound suggests possible implant rupture, the diagnosis should be confirmed by MRI. Screening with MRI may be more appropriate after five years, when the rate of implant rupture is higher.

Plastic and Reconstructive Surgery is published by Lippincott Williams & Wilkins, part of Wolters Kluwer Health.