Browsing by Subject "IMAGING"
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Item Improved fluorescence-enhanced optical imaging and tomography by enhanced excitation light rejection(2009-05-15) Hwang, Kil DongFluorescence enhanced optical imaging and tomography studies involve the detection of weak fluorescent signals emanating from nano- to picomolar concentrations of exogenous or endogenously produced fluorophore concurrent with the rejection of an overwhelmingly large component of backscattered excitation light. The elimination of the back-reflected excitation light of the collected signal remains a major and often unrecognized challenge for further reducing the noise floor and increasing sensitivity of small animal fluorescence imaging. In this dissertation, we adapted collimating and gradient index (GRIN) lenses in an existing frequency-domain system to improve excitation light rejection and enhance planar and tomographic imaging. To achieve this goal, we developed planar and tomographic imaging systems based upon ray tracing calculations for improved rejection of excitation light. The ?out-of-band (S (?x))? to ?in-band (S (?m) - S (?x))? signal ratio assessing excitation leakage was acquired with and without collimating optics. The addition of collimating optics resulted in a 51 to 75% reduction in the transmission ratio of (S (?x))/ (S (?m) - S (?x)) for the phantom studies and an increase of target to background ratio (TBR) from 11% to 31% in animal studies. Additionally, we presented results demonstrating the improvement of model match between experiments and forward simulation models by adaptation of GRIN lens optics to a breast phantom study. In particular, 128 GRIN lenses on the fiber bundle face were employed to align the collected excitation and emission light normal to the filter surface in an existing frequency-domain system. As a result of GRIN lens collimation, we reduced the transmission ratio between 10 and 86 % and improved the model match for tomographic reconstruction of one (1 cm3) and two (0.1 cm3) targets in a 1087 cm3 of breast phantom. Ultimately, this work improves the sensitivity of NIR fluorescence imaging by enhancing the rejection of excitation light and shows that the current sensitivity challenges for translating fluorescence-enhanced optical imaging into the clinic can be overcome.Item Tumor angiogenesis, O2 saturation, glucose and amino acid metabolisms study using functional imaging(2009-05-15) Xie, XueyiThis research is primarily focused on the study of tumors in experimental animal models using functional imaging in the presence of various contrast agents. The study of malignant tumor angiogenesis, oxygen saturation, glucose and amino acid metabolisms will lead to better methods for cancer detection as well as diagnosing and managing cancer. Non invasive in vivo diagnostic imaging technique is an area of great clinical interest in present days. In this study, noninvasive in vivo photoacoustic tomography and conventional fluorescence imaging together with multiphoton microscopic tomography were implemented to study the malignant tumor morphology and physiology. Tumor structure and angiogenesis were successfully imaged by photoacoustic tomography and conventional fluorescence imaging. The important malignant tumor cellular parameters such as oxygen saturation and ?v?3 integrin concentration were measured in living small animals (rodents) using the novel photoacoustic tomography technique. By implementing multiphoton microscopy using Cy3.5 NHS ester contrast agent, tumor amino acid metabolism was successfully studied in cell culture. This method will at least give you a relative concentration map of amino acid in cells. Non invasive in vivo imaging can be achieved by modifying the current multiphoton imaging setup. A new method for studying amino acid and glucose metabolisms of tumor cells using multiphoton imaging was developed.