Comparison between intrinsic and extrinsic contrast for malignancy detection using NIR mammography

In this work we reconstruct and compare NIR images of the intrinsic and extrinsic distribution of the absorption coefficient in the breast. The NIR protocol followed involves optical imaging before and after the administration of the NIR contrast agent Infracyanine 25 or Cardiogreen(R) and runs in parallel with the MRI examination protocol, while the patient is located in the magnet. For imaging purposes we employ a time-resolved imager using two wavelengths at 780 and 830 nm. The tomographic needs are served with a perturbation analysis that solves the heterogeneous diffusion equation and creates the forward model. Inversion is performed using the algebraic reconstruction technique (ART). Coregistration with Gd-DTPA enhanced MR images allows for direct and unequivocal comparison between optical and MR images. We focus on the comparison between the use of intrinsic or extrinsic contrast to differentiate breast tissue types. The distribution of the NIR contrast agent yields very good coregistration with the MR contrast enhanced images and that it allows accurate quantification. Our results greatly exemplify the need for NIR contrast agents in optical mammography. Conversely imaging of the intrinsic coefficient is associated with more experimental uncertainties leading to less quantification accuracy.