Expected resolution and detectability of adenocarcinoma tumors within human breast in time-resolved images

摘要

Abstract: The prospects for time-resolved optical mammography rests on the ability to detect adenocarcinoma within the breast with sufficient resolution and specificity to compete with X-ray mammography. We characterized the optical properties of an unusually large (6 cm diameter) fresh adenocarcinoma and normal breast tissue (determined by histology to be predominantly adipose tissue) obtained from a patient undergoing mastectomy. Large specimens (5 mm thick and 3 cm wide) allowed the determination of absorption and scattering coefficients and their spatial heterogeneity as probed with a 1 mm diameter laser beam at 633 nm and 800 nm utilizing total reflectance and transmittance measure with integrating spheres. The difference between scattering coefficients of the malignant tumor and those of normal (principally adipose) breast tissue at 633 nm was much greater than the heterogeneity within each sample. This scattering difference is the principal source of contrast, particularly in time-resolved images. However, the high scattering coefficient of normal breast tissue at 633 nm limits the practicality of time-resolved mammography of a human breast compressed to 5 cm. Although the scattering coefficient of the normal breast tissue decreases at 800 nm, the differences between the optical properties of normal and abnormal breast tissue also are reduced. We used these empirical results in theoretical expressions obtained from random walk theory to quantify the expected resolution, contrast, and the detected intensity of 3, 6, and 9 mm tumors within otherwise homogeneous human breasts as a function of the gating-time of time-resolved optical mammography.!12