Rebecca C Booi MS, Presenter: Nothing to Disclose

Matthew O'Donnell PhD, Abstract Co-Author: Nothing to Disclose

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

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

Carl Chalek PhD, Abstract Co-Author: Nothing to Disclose

Paul Langford Carson PhD, Abstract Co-Author: Nothing to Disclose

US-based reconstructive elasticity imaging has great potential for diagnosis and characterization of breast lesions. Applying external strain with a mammographic paddle as part of a combined 3D US/Digital X-ray system provides more uniform deformation and breast stability, offering opportunities to improve image fidelity. This success could be limited by chest wall (CW) and cardiac motion during the exam, causing extraneous decorrelation and artifacts. We investigated 4 causes of motion and resulting decorrelation to determine how to minimize these on strain images.

Each breast in 7 subjects was imaged using a GE Logiq 9 US unit with an M12L array at 10MHz. Patients were asked to 1) hold their breath, 2) breathe shallowly, 3) breathe deeply, and 4) talk. In each case, 91 RF frames were acquired over 2.1 sec and correlated to frame 1 using conventional 2D phase sensitive speckle tracking algorithms. Mean correlation coefficients (R) were calculated as a function of time and distance from the CW. In one case, strain images were acquired by compressing the breast as the patient repeated these 4 actions.

Breathing motion was evident in correlation plots. Shallow breathing correlations remained steady over time and distance, yielding an R > 0.9 in all but one acquisition (Ravg = 0.96). With no breathing, mean R = 0.93 and slowly decreased over time due to chest relaxation. Deep breathing would make elasticity imaging impossible (R < 0.81). Talking was most variable (R = 0.82-0.99), depending on speech volume and frequency. In some cases, more motion was observed < 1cm from the CW. Comparable motion occurred bilaterally, indicating that left breast cardiac motion is not an additional problem. Excessive patient motion (R < 0.9) created artifacts in strain images that obscured our ability to assess tissue hardness.

In elasticity imaging, CW motion is acceptable if voluntary motions are avoided and scanning time remains short (~ 2 sec). Shallow breathing minimizes motion more than no breathing. Cardiac motion did not cause artifact. Acquiring redundant data on the same plane could help optimize strain images by allowing us to choose scans with minimal motion.

C.C.: Author works for General Electric.R.C.B.,M.O.,R.E.,M.A.R.,P.L.C.: Authors work on a federal grant that is joint with General Electric.

Booi, R, O'Donnell, M, Erkamp, R, Roubidoux, M, Chalek, C, Carson, P, Consequences of Chest Wall Motion on Ultrasonic Elasticity Imaging of the Breast.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4418799.html