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Thứ Tư, 9 tháng 4, 2014


Ultrasound Fast Alternative to MRI for Breast Implant Status
Pam Harrison
April 01, 2014

LAS VEGAS — High-resolution ultrasound done in a physician's office is a fast, convenient, and friendly alternative to MRI for ascertaining the status of breast implants, a pilot study suggests.

Researchers found a "higher than expected" rotation rate in 2 types of shaped cohesive gel implants and detected 2 ruptures that were later confirmed on MRI.

Dr. William Adams Jr.
"Clinically, our rotation rate is only about 2%. It was surprising that we were definitely able to show with ultrasound that the rotation rate was much higher," said William Adams Jr., MD, clinical associate professor of plastic surgery at the University of Texas South Western Medical Center in Dallas.

"This means that a fair number of rotations are going unnoticed by patients. We haven't had this type of information about shaped implants before, so it's something we can add to our discussion with patients when they are considering these types of surgeries," he told Medscape Medical News.

The study results were presented here at the American Institute of Ultrasound in Medicine (AIUM) 2014 Annual Convention in Las Vegas, Nevada.

MRI Screening

Currently, the US Food and Drug Administration (FDA) recommends that breast implant recipients undergo MRI screening 3 years after implantation and every other year thereafter to determine whether an implant has ruptured. However, even in the best studies, there is at least a 15% false-positive rate, Dr. Adams noted.

This means that a woman might be rescheduled for breast implantation surgery only to have the surgeon discover the implant was intact.

In addition, "MRIs aren't much fun for the patient; they're loud, the patient has to lie still for a long time, and they are very expensive," said Dr. Adams.

Because of this, very few women ever go for an MRI, especially when their implants seem to be fine, he said.

In fact, rotation is not an issue with round breast implants; orientation is an issue only for implants that resemble the natural shape of the breast, where rotation could result in a misshapen breast. Rotational status cannot be determined with MRI.

The researchers evaluated 74 patients with bilateral shaped cohesive gel implants using ultrasound. Of the implants in this cohort, 48 were Allergan 410 and 100 were Mentor CPG.

Both types of implants have a textured outer shell and untextured fiducial markers on their surface at the lower pole, which allow the surgeon to feel and assess implant orientation during surgery, the researchers report. It was previously assumed that textured implants become anchored to the surrounding tissue and do not rotate.

The fiducial markers were imaged using a Terason 2000+ ultrasound system with a TouchView linear array probes.

The ultrasound examination itself is painless and nonthreatening, much like the fetal–maternal ultrasound screening many women are familiar with, Dr. Adams noted.

Marker orientation relative to the nipple was determined by using a clock-hand position, where 6 was directly downward and 3 directly to the right. Any orientation between 5 and 7 o'clock was considered to be "unrotated."

On ultrasound examination, which took place 6 months to 7 years after implantation, 25% of the Mentor CPG implants and 21% of the Allergan 410 implants had rotated from their original position.

"The vast majority of these rotations will 'self-reverse' and the implant will reorient itself over time, so it's somewhat of a dynamic process," said Dr. Adams.

"Still, my personal opinion is that ultrasound will eventually replace MRI. It just has to have FDA 'blessing' before surgeons can openly recommend it," he explained.

The percentage of women who follow the FDA recommendation and go for MRI screening is not known, said Brad Bengtson, MD, from the Bengtson Center for Aesthetics and Plastic Surgery in Grand Rapids, Michigan. However, he told Medscape Medical News that he would be "shocked" if it were over 3%.

Dr. Bengtson and his colleagues published the first landmark evaluation of high-resolution ultrasound for the detection of breast implant shell failure (Aesthet Surg J. 2012;32:157-174). They concluded that the ultrasound approach is equivalent to MRI in terms of visualization of implant rupture, but that its relative accessibility, affordability, and real-time visualization represent "significant potential advantages" over MRI for this indication.

"Since our original research began in 2012, we have imaged more than 500 patients and detected more than 80 patients with implant shell failure. And in every patient with a rupture who has gone to surgery, shell failure has been confirmed, with no false-positives to date," Dr. Bengtson reported. "Patients need a better solution than MRI to follow their breast implants over time; unquestionably, that technology is high-resolution ultrasound."

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