Mitchell M. Goodsitt PhD, Presenter: Nothing to Disclose

Marilyn A. Roubidoux MD, Abstract Co-Author: Nothing to Disclose

Ramon Erkamp PhD, Abstract Co-Author: Nothing to Disclose

Christine R. Lashbrook BA, Abstract Co-Author: Nothing to Disclose

Sumedha P. Sinha BS, Abstract Co-Author: Nothing to Disclose

Gerald L. LeCarpentier PhD, Abstract Co-Author: Nothing to Disclose

We are developing a device that permits 3D x-ray and ultrasound (US) imaging of the breast in the same geometry via a special compression paddle. One potential limitation is incomplete ultrasound coverage due to air gaps between the breast periphery and the paddle. We investigated the magnitude of this problem and possible solutions.

To estimate incomplete ultrasound coverage, we measured the fraction of the breast surface area that was in direct contact with the compression paddle by using visual tracings of the breast margins of 10 patient breasts (7 breast cancer, 3 normal). The linear dimensions of the gaps at the periphery were also measured. We evaluated a variety of ultrasound coupling agents and techniques to fill in air gaps at the breast periphery, and measured the amount of gap filling from US images of 10 volunteers (4 with cysts). The percentage of total gap filled was also estimated when possible.

The fraction of the breast surface area in direct contact with the compression paddle ranged from 35% to 74% (mean=56±15%). The linear dimensions of the air gaps at the breast periphery ranged from 0.8cm to 4.3cm (mean=2.2±0.9cm). A high viscosity bubble-free ultrasound gel was found to be the best coupling agent. Two methods of infusing this gel into the air gaps at the breast periphery were developed. One employed a manually squeezed syringe and the other utilized a controlled force provided by a high pressure gas/valve system. For the 10 volunteers, the linear dimensions of the gap filled with gel and image artifact-free ranged from 0.7cm to 4.7cm (mean=1.8±0.6 cm). The percentage of the total gap filled and artifact-free was 42% to 85% (mean=61±10%), which should be adequate as virtually no lesions are at the extreme periphery. Also, the total coverage afforded by the gel including minor artifacts was significantly greater.

Completeness of coverage with US in a compressed breast in a combined whole breast mammography-US imaging system is improved by the infusion of bubble free gel into the air gap between the breast curvature and the compression plate at the periphery. Supported by NIH Grants CA91713-01A2 and P01CA87634

Goodsitt, M, Roubidoux, M, Erkamp, R, Lashbrook, C, Sinha, S, LeCarpentier, G, Ultrasound Coverage for a Combined 3D X-Ray/Ultrasound Breast Imaging System.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4406688.html