Calculation of Silicone Breast Implant Volumes Using Breast Magnetic Resonance Imaging
Accepted 9 February 2009.
Background
Patients needing silicone gel–filled breast implant surgical revision often do not have information as to the size of their implants. Clinical estimates may be erroneous and an accurate, in vivo method of determining breast implant volume would be very useful in planning surgery.
Objective
Our objective was to determine whether magnetic resonance imaging (MRI) scans of the breast in combination with a computer-assisted detection (CAD) system could provide accurate estimation of implant volumes in patients with silicone gel–filled implants, using known implant volumes for comparison.
Methods
All MRI scans were performed for medical necessity before implant revision surgery or for follow-up. Scans and silicone implant volume calculations were performed in 20 patients (39 breasts). Fifteen patients (n = 27 breasts) had known implant volumes. The MRI images were analyzed blindly by a single radiologist using the image processing features of an MRI CAD system (DynaCAD; Invivo, Birmingham, MI) in a novel way. Computed implant volumes were compared to known implant volumes obtained from documented preoperative notes (n = 17) or following implant removal via implant markings (n = 10).
Results
Average deviation of the 27 known implant volumes from those calculated by MRI DynaCAD analysis was only 0.82% (SD, 3.95%). In four of 27 breasts (14.8%), MRI calculations matched the clinical volumes exactly. The widest volume deviation range for all implants was +11.4% to −4.44%. A variety of implant types were found, with 11 confirmed ruptures.
Conclusions
The calculation of silicone gel–filled breast implant volume using breast MRI scans and a commercially-available CAD system appears to be sufficiently accurate that it may have significant clinical benefit in planning revision implant surgery. Calculations can be easily obtained in five minutes. To our knowledge, this is the first report describing this method to reliably measure silicone implant volumes preoperatively.
Reprint requests: Ross Rudolph, MD, Scripps Clinic, MS 115, 10666 N. Torrey Pines Rd., La Jolla, CA 92037
DISCLOSURES
The authors have no financial interest in and receive no compensation from manufacturers of products mentioned in this article.
1 Dr. Rudolph is a Voluntary Clinical Professor of Surgery at the University of California San Diego, San Diego, CA, and is the Head of the Division of Plastic and Reconstructive Surgery at the Scripps Clinic, La Jolla, CA.
2 Dr. Forcier specializes in breast imaging in the Department of Radiology at the Scripps Clinic, La Jolla, CA.
ABSTRACT