MRI Position Affects Evaluation of Residual Breast Cancer

July 11, 2016

Adding intraoperative supine MR imaging to standard prone imaging may increase accuracy when evaluating breast cancer.

Intraoperative supine breast MR imaging combined with standard prone breast MR imaging may help clinicians evaluate for residual tumor immediately after breast-conserving surgery (BCS), according to a study in Radiology.

Researchers from Brigham and Women’s Hospital in Boston, MA, used intraoperative supine imaging to quantify breast tumor deformation and displacement secondary to the change in patient positioning from imaging (prone) to surgery (supine) and to evaluate residual tumor immediately after BCS.

Twelve women with clinical stage I or II invasive breast cancer participated in this phase I study, undergoing lumpectomy and postsurgical intraoperative supine MR imaging. Six of 12 patients underwent both pre- and postsurgical supine MR imaging. The researchers assessed geometric, structural, and heterogeneity metrics of the cancer and distances of the tumor from the nipple, chest wall, and skin. Mean and standard deviations of the changes in volume, surface area, compactness, spherical disproportion, sphericity, and distances from key landmarks were computed from tumor models. Imaging duration was also recorded.

The findings showed mean differences in tumor deformation metrics between prone and supine imaging:

Volume: 23.8%

Surface area: 6.5%

Compactness: 16.2%

Sphericity: 6.8%

Decrease in spherical disproportion: 11.3%

The researchers also found that all tumors were closer to the chest wall on supine images than on prone images. There was no evidence of residual tumor on MR images obtained after the procedures.

The mean duration of preoperative supine MR imaging was 25 minutes, and 19 minutes for postoperative MR imaging.

"Accounting for change in size and shape caused by displacement and deformation of the tumor between standard imaging in the prone position and operative supine position, our analysis highlights that supine MRI before surgery may provide surgeons with more detailed and accurate information and could lead to effective tumor removal," lead author Eva C. Gombos, MD, a radiologist at BWH, said in a release.[[{"type":"media","view_mode":"media_crop","fid":"50062","attributes":{"alt":"","class":"media-image media-image-right","id":"media_crop_223074010499","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"6090","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"height: 271px; width: 401px; float: right;","title":"Breast and tumor deformation and displacement in six patients. Prone diagnostic and supine preprocedural contrast-enhanced MR images are superimposed on one another with 3D prone (blue) and supine (green) tumor models after iterative closest point registration. Image courtesy of Radiology. ©RSNA, 2016.","typeof":"foaf:Image"}}]]

"Supine MRI, when performed in addition to standard prone breast MRI, may help detect a remnant tumor and ensure clear margins to prevent re-operation. Among women undergoing breast conserving surgery, 15-40 percent need to have a second operation to remove remnant tumor," senior author Mehra Golshan, MD, distinguished char in surgical oncology at BWH, added in the release.

More research is needed, but if these findings are validated in future, larger studies, intra-operative and pre-operative supine MR imaging would aid in accurate planning for removal of the tumor and reducing further surgery, the researchers concluded.