Abstract
.Significance: Longitudinal tracking of hemodynamic changes in the breast has shown potential for neoadjuvant chemotherapy (NAC) outcome prediction. Spatial frequency domain imaging (SFDI) could be suitable for frequent monitoring of shallow breast tumors, but strong sensitivity to superficial absorbers presents a challenge.Aim: We investigated the efficacy of a two-layer SFDI inverse model that accounts for varying melanin concentration in the skin to improve discrimination of optical properties of deep tissue of the breast.Approach: Hemodynamic changes in response to localized breast compression were measured in 13 healthy volunteers using a handheld SFDI device. Epidermis optical thickness was determined based on spectral fitting of the model output and used to calculate subcutaneous optical properties.Results: Optical properties from a homogeneous model yielded physiologically unreasonable absorption and scattering coefficients for highly pigmented volunteers. The two-layer model compensated for the effect of melanin and yielded properties in the expected range for healthy breast. Extracted epidermal optical thickness was higher for higher Fitzpatrick types. Compression induced a decrease in total hemoglobin consistent with tissue blanching.Conclusions: The handheld SFDI device and two-layer model show potential for imaging hemodynamic responses that potentially could help predict efficacy of NAC in patients of varying skin tones.
Highlights
The multi-center ACRIN 6691 trial of diffuse optical spectroscopic imaging (DOSI) found tumor tissue oxygen saturation measured within 10 days of treatment to be predictive of pCR.[12]
An independent study of diffuse optical tomography (DOT) for neoadjuvant chemotherapy (NAC) monitoring found that a decrease in total hemoglobin concentration at the two-week time point correlated with residual cancer burden.[7]
As determined empirically from in vivo data and the optimization procedure described in Sec. 2.3.3, the four lookup table (LUT) represent a range from low to high melanin concentration in μa;epið662Þ
Summary
Near-infrared (NIR) optical imaging methods have shown potential for prediction of treatment outcome in women undergoing neoadjuvant chemotherapy (NAC) for breast cancer via longitudinal tracking of hemoglobin concentration within the breast.[1,2,3,4,5,6,7,8,9,10,11,12,13] Pathologic completeJournal of Biomedical OpticsDownloaded From: https://www.spiedigitallibrary.org/journals/Journal-of-Biomedical-Optics on 02 Nov 2021 Terms of Use: https://www.spiedigitallibrary.org/terms-of-useMay 2021 Vol 26(5)Robbins et al.: Two-layer spatial frequency domain imaging of compression-induced hemodynamic. . .response (pCR) to NAC (assessed histologically after surgery) is associated with improved survival,[14,15] but the results of structural imaging modalities such as ultrasonography and x-ray mammography are poor predictors of patient outcome.[16,17] Predicating the response early in the course of therapy could potentially enable treatment alternatives. Near-infrared (NIR) optical imaging methods have shown potential for prediction of treatment outcome in women undergoing neoadjuvant chemotherapy (NAC) for breast cancer via longitudinal tracking of hemoglobin concentration within the breast.[1,2,3,4,5,6,7,8,9,10,11,12,13] Pathologic complete.
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