Three-dimensional dynamic optical coherence tomography for breast tumor margin assessment

Intraoperative margin assessment techniques are needed to reduce the re-excision rate in breast-conserving surgery. Optical coherence tomography (OCT) is a non-invasive imaging technique capable of rapid three-dimensional (3-D) imaging of the internal microstructure of tissues. However, there is often low contrast between morphological features in breast tissue. Dynamic OCT (d-OCT), which provides additional contrast derived from the temporal variance of the OCT signal caused by intrinsic motion within the tissue, may provide a solution. However, few studies have applied it to breast tumor margin assessment. In this study, we acquired 3-D d-OCT images of ten human mastectomy specimens and three wide local excisions from breast-conserving surgery (BCS) procedures and, in each case, performed co-registered histology for validation. To optimize the trade-off between spatial resolution, temporal resolution, and acquisition time, we considered a range of acquisition settings. Several methods for visualizing d-OCT images were investigated, including Fourier weighted mean frequency, Fourier power spectral analysis, using red-green-blue (RGB) and hue-saturation-value (HSV) color spaces, and phase variance. We present d-OCT images of invasive ductal carcinoma (IDC), ductal carcinoma <i>in situ</i> (DCIS), invasive lobular carcinoma (ILC), and lobular carcinoma <i>in situ</i> (LCIS), and show that the contrast between malignant and benign regions is consistently higher with d-OCT than using OCT intensity alone. The improved contrast may derive from increased proliferation rates and collagen deposition in cancerous tissue compared to benign tissue. We believe that our results demonstrate that d-OCT has the potential to improve intraoperative tumor margin assessment during breast-conserving surgery.