In vivo determination of scattering properties of healthy and malignant breast tissue by use of multi-diameter-single fiber reflectance spectroscopy (MDSFR)

Abstract

Elastic scattering of light in tissue offers a natural biologic contrast that can be used to classify tissue for diagnostic purposes. For a single fiber reflectance spectroscopy setup, which uses a single multimode optical fiber with diameter dfib for both illumination and detection, our group has previously reported a relationship between the single fiber reflectance (SFR) signal and the dimensionless scattering (&mu;&prime;_sd_fib). Based on this relationship, the multi-diameter single fiber reflectance method (MDSFR), was developed. This method allows the extraction of &mu;&prime;_S and a phase function dependent parameter &gamma;=(1-g₂) / (1-g₁) from tissue by taking multiple SFR measurements with different fiber diameters. Limitations and the sensitivity of the MDSFR method have been discussed previously based on an <i>in silico </i>analysis and the feasibility of the method has been proven experimentally during measurements in scattering phantoms containing polystyrene spheres. In the current study we will present data from an in-vivo clinical study utilizing MDSFR to determine tissue scattering properties of healthy and malignant breast tissue, on patients undergoing biopsy of a suspicious lesion found during mammographic breast imaging. Here MDSFR measurements are performed with a custom made disposable probe, incorporating two fiber diameters (0.4 and 0.8 mm), which is inserted through the biopsy needle before the biopsy is taken, allowing in vivo spectroscopic measurements of tumor center and healthy tissue.