Angiogenesis is an important factor for further tumor growth and thus could be an attractive therapeutic target. Optical imaging can provide a non-invasive way to measure the permeability of tumor blood vessels and assess the tumor vasculature. We have developed a dual-channel near-infrared fluorescence system for simultaneous measurement of the pharmacokinetics of tumorous and normal tissues with exogenous contrast agents. This frequency-domain system consists of the light source (780 nm laser diode), fiber optics, interference filter (830 nm) and the detector (PMT). The fluorescent contrast agent used in this study is Indocyanine Green (ICG), and the normal dosage is 100 μl at a concentration of 5 μM. In vivo animal study is performed on the K1735 melanoma-bearing mouse. The fluorescence signals both tumorous and normal tissues after the bolus injection of ICG through the tail vein are continuously recorded as a function of time. The data is fitted by a double-exponential model to reveal the wash-in and wash-out parameters of different tissues. We observed an elongated wash-out from the tumor compared with normal tissue (leg). The effect of radiation therapy on the tumor vasculature is also discussed.
The goal of our study is to develop a time-dependent three-compartment model of beacon delivery to simulate the distribution of Indocynanine Green (ICG) in cancer tissue by using JSIM development environment of model simulation and data analysis. We studied the major factors that contribute to distribution of ICG in our model. The simulation results show that our time-dependent three-compartment model can describe the delivery of ICG injected intravenously into the human subject and assist in breast cancer detection.
Diffuse Optical Tomography (DOT) in the Near Infrared Spectral window (NIR) offers new possibilities for medical imaging. And using DOT, Indocyanine green (ICG) is found to be a useful blood pooling contrast agent for optical tumor detection. Here we introduce our efforts on study of breast cancer image reconstruction using ICG as a contrast agent. To improve the signal-to-noise ratio, we developed an effective method to analyze and process the raw data acquired from a CWS (Continuous Wave Spectroscopy) system. Differential absorption images of breast cancers are reconstructed by using ART (Algebraic Reconstruction Technique) which uses the diffusion equation within the Rytov approximation. The experiment device is a combination of sixteen light sources (tungsten bulb) and sixteen light detectors (silicon photodiodes). These sources and detectors are located on a circular holder where the human breasts are placed, each other at equal distance (11 angle apart). It takes a few seconds to acquire data since one source is on, while all the detectors simultaneously detect the photons. So an image includes 16*16 data points. Results from clinical trial in Japan and China show that there is a high concentration of ICG in the location of a cancer, suggesting high blood volume pooling and the usefulness of ICG detecting optically breast cancers.
In-phase and Quadrature Phase Detection System (I&Q System) can be used to detect the clinic-related parameters such as hemoglobin concentration and saturation. We set up an effective multi-wavelength fitting model and method to calibrate the tissue optical properties such as the reduced scattering factor ((mu) s) and the absorption factor ((mu) a), which can be calculated from the measured amplitude and phase shift of I&Q system. Then using the calibrated tissue optical parameters, we can get better results for hemoglobin concentration and saturation by our proposed algorithm of fitting multi-wavelength absorption coefficient ((mu) a) of the medium than those from the previous I&Q system based on the two-wavelength absorption coefficient calculation. Our algorithm is used in the clinical experiments with five wavelengths (680 nm, 750 nm, 780 nm, 810 nm, 830 nm) for the necks' and arms' saturation test between normal persons and tumor-bearing patients.