Image reconstruction and evaluation of system performance for optical fluorescence tomography

摘要

Diffuse optical tomography is a non-invasive method aiming at the detection of breast cancer. The sensitivity and specificity of the method can be increased if a fluorescent contrast agent is used that accumulates in malignant lesions. Recently, Philips developed an optical scanner, where the patient is lying on a bed, with one breast hanging freely in a cup containing an optical matching fluid. 507 optical fibers are mounted in the surface of the measurement cup. The breast is illuminated sequentially by half of these fibers while the other half is used to collect the light that is emanating from the breast. The system uses near-infrared light of continuous wave solid-state lasers to illuminate the breast at four different wavelengths. A complete measurement takes less than ten minutes and involves five breast scans: transmission data are collected for four wavelengths, and fluorescence data for excitation at one wavelength. Here, we present the image reconstruction scheme and a novel method to assess the system performance in terms of lesion detectability. This method uses a statistical significance test on simulated data with and without a lesion. It allows the quantification of the detectability of lesions for different size, position, or contrast of the lesion. It also allows to analyze the potential impact of system improvements or to judge the performance of an image reconstruction algorithm.