Concurrent diffuse optical tomography, spectroscopy and magnetic resonance imaging of breast cancer
Abstract
Diffuse Optical Tomography (DOT) in the Near Infrared NIR offers the potential to perform non-invasive three-dimensional quantified imaging of large-organs in vivo. The technique targets tissue intrinsic chromophores such as oxy- and deoxy-hemoglobin and the uptake of optical contrast agents. This work considers the DOT application in studying the vascularization, hemoglobin saturation and Indocyanine Green (ICG) uptake of breast tumors in-vivo as measures of angiogenesis, blood vessel permeability and oxygen delivery and consumption. To realize this work an optical tomographer based on the single-photon-counting time-correlated technique was coupled to a Magnetic Resonance Imaging (MRI) scanner. All patients entered the study were also scheduled for biopsy; hence histopathological information was also available as the "Gold Standard" for the diagnostic performance. The feasibility of Diffuse Optical Tomography to image tissue in-vivo is demonstrated by direct comparison of contrast-enhanced MRI and DOT images obtained from the same breast under identical geometrical and physiological conditions. Additionally, the effect of tissue optical background heterogeneity on the imaging performance is studied using simulations. We also present optimization schemes that yield superior reconstruction and spectroscopic capacity when probing the intrinsic and extrinsic contrast of highly heterogeneous optical media. The simultaneous examination also pioneers a hybrid diagnostic modality where MRI and image-guided localized diffuse optical spectroscopy (DOS) information are concurrently available. The approach employs the MR structural and functional information as a-priori knowledge and thus improves the quantification ability of the optical method. We have employed DOS and localized DOS to quantify optical properties of tissue in two and three wavelengths and obtain functional properties of malignant, benign and normal breast lesions. Generally, cancers exhibited higher hemoglobin concentration, lower hemoglobin saturation and higher ICG uptake than normal and benign lesions. The use of DOT and localized DOS is found to be a valuable clinical tool to study tissue function. The potential to use DOT for early breast cancer detection by employing emerging classes of optical contrast agents that target highly specific biochemical cancer properties in the cellular level has also been demonstrated.
Recommended Citation
Vasilis Ntziachristos,
"Concurrent diffuse optical tomography, spectroscopy and magnetic resonance imaging of breast cancer"
(January 1, 2000).
Dissertations available from ProQuest.
Paper AAI9976463.
http://repository.upenn.edu/dissertations/AAI9976463
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