Patient Repositioning May Deform Breast MRI

A new suggests that changes in patient positioning between MRI imaging and surgery results in deformation and displacement of the tumor during breast-conserving surgery (BCS).

Researchers at Brigham and Women's Hospital (BWH; Boston, AM, USA) conducted a study in 12 women who underwent lumpectomy and postsurgical intraoperative supine MRI imaging; six of 12 patients completed both a prone and a supine presurgical MRI. The geometric, structural, and heterogeneity metrics of the cancer tumor and distances of the tumor from the nipple, chest wall, and skin were computed, as were mean and standard deviations of the changes in volume, sphericity, distances from key landmarks, and other measures.

The results showed that the specifications of the tumor, including size and location in the breast, were substantially different between supine and prone MRI. The mean differences in tumor deformation metrics between prone and supine imaging were as follows: for volume, 23.8%; for surface area, 6.5%; for compactness, 16.2%; for sphericity, 6.8; and for decrease in spherical disproportion, −11.3%. All tumors were closer to the chest wall on supine images than on prone images. No evidence of residual tumor was seen on MRI obtained after the procedures. The study was published on June 22, 2016, in Radiology.

“Our analysis highlights that supine MRI before surgery may provide surgeons with more detailed and accurate information and could lead to effective tumor removal,” said lead author radiologist Eva Gombos, MD. “If validated in future large studies, intra-operative, and, more importantly, pre-operative supine MRI could be expected to help the surgeon in accurately planning removal of the tumor and reducing the need for re-operation which negatively impacts the patient emotionally, delays post-operative therapy and increases infection rates and cost.”

Traditionally, patients who are scheduled to undergo BCS lumpectomy undergo a breast MRI prior to surgery to help inform the surgeon about the size, shape, and location of the tumor. These MRIs are performed with the patient lying prone (face down), while the surgery is performed with the patient lying supine (face up). Supine MRI, when performed in addition to standard prone breast MRI, may help detect a remnant tumor and ensure clear margins.

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