Our goal is to devise new approaches for noninvasive, quantitative optical spectroscopic and tomographic imaging of deep tissue structures for clinical screening and monitoring of physiological parameters. To achieve our goal, we have undertaken a multifaceted theoretical, computational, experimental, and clinical research program that includes the time-resolved transillumination of thick tissue applied to quantitative spectroscopy of breast tumors and the use of specific fluorescent markers (e.g., ligands) for identifying molecular biology of disease processes applied to noninvasive biopsy of Sjögren’s syndrome and for lymphatic imaging for sentinel node detection. We are involved in several clinical studies, including an NCI protocol to use oblique angle reflectometry for noninvasive monitoring of inflammation in oral cavity, an NIDCR/NINDS clinical study to evaluate the drug response of patients experiencing complex regional pain syndrome, and another NCI-sponsored clinical trial to evaluate the effectiveness of anti-angiogenesis drug treatment for Kaposi sarcoma.

Time-Resolved Tomography of Thick Tissue
Chernomordik, Hattery, Gandjbakhche; in collaboration with Zaccant, Cubbedu, Rinneberg
In collaboration with researchers who have provided in vivo measurements on human breast at the Physikalisch-Technische Bundesanstalt of Berlin and Politecnico di Milano, we have developed and are using random walk methodology to quantify optical properties of breast tumors. We have performed data analysis on distributions of times of flight for photons transmitted at several wave lengths through the breast as recorded in vivo by time-domain scanning mammography developed by the Berlin and Milan groups. We are able to reconstruct the size of the tumors and their optical properties and those of the surrounding tissue. We have analyzed 10 sets of data and, from the absorption coefficients, estimated blood oxygen saturation and total blood volume for the tumors and the surrounding tissue. We found that some tumors, mostly invasive ductal carcinoma, are hypoxic and have increased blood volume. We are studying the correlation between the spectroscopic signatures of the breast tumors and the risk associated with the outcome of the therapy. We are continuing to refine our theoretical algorithms to make the analysis less time-consuming.

3D Reconstruction of Localized in Vivo Fluorescence
Chernomordik, Hattery, Gannot I, Gannot G, Gandjbakhche
The development of specific fluorescently labeled cell surface markers has opened the possibility of specific and quantitative noninvasive diagnosis of tissue changes. We are pursuing the development of a fluorescence scanning imaging system that can perform a “noninvasive optical biopsy” of Sjögren’s syndrome (SS), potentially replacing the currently used histological biopsy. In our animal experiments, we have devised an imaging system to quantify the concentration of fluorescinated antibodies binding to B or T tumor cells previously injected into the oral cavity of mice. Preliminary results show that our imaging system along with our theoretical algorithm is able to monitor noninvasively the concentration of fluorophore signals as well as the pharmaco-kinetics associated with wash-out of the antibodies.

We are also continuing our study on the use of infrared-dependent fluorescent detection methods to determine the position of sentinel node(s) to replace currently used detection by radioactive particles. We have extended our analysis of different phantom data and ex vivo tissue to confirm the potential of the random walk-based theoretical approach to reconstruct with good accuracy three-dimensional positions of deeply embedded fluorophores. We are starting animal experiments with near-infrared nanoparticles to study the drainage of the particles through the lymphatics.

Oblique Angle Reflectometry for Noninvasive Monitoring of Inflammation: Application to Chemopreventive Drugs
Hattery, Hekmat, Gandjbakhche; in collabora-tion with Mulshine
Inflammatory cell populations produce cytokines that can specifically stimulate growth of evolving cancer clones. Given that normal epithelium shares many biological properties with cancer cells, it also responds to the chronic presence of mitogenically active cytokines by accelerated growth (hyperplasia); normal cell hyperplasia provides a measure of the promotional environment of a cancer clone. At NCI, a Phase II trial is under way to determine the effectiveness of cyclooxygenase (COX) inhibitor on oral leukoplakia. The effectiveness will be monitored by surgical biopsy with its associated morbidity. As a less morbid approach to monitoring patient response, we have developed a noninvasive quantitative epithelial inflamma-tion measuring device that may be used to evaluate the general state of the oral mucosa and monitor the effectiveness of chemopreventive treatment regimes. The device measures diffuse reflectance from a low-power optical wavelength source, which inserts photons at specific angles into the tissue. As the angle of insertion approaches parallel with the epithelial surface, the mean penetration of the photons becomes smaller and the photons spend more time in the epithelial layer. Wave lengths of interest are those with high tissue absorption, thus limiting detected photons to those with few scattering events and confining to the surface layers the tissue volume that has been interrogated. From a theoretical point of view, the approach permits the use of integral equations to describe photon migration in a two-layer tissue model. We performed several phantom experiments that used acrylamide gel phantoms with high absorption covered with a thin liquid layer, thereby simulating the epithelial layer of tissue. We compared the data with the theoretical predictions after collecting and analyzing, by means of our predictive model, ten sets of data from five patients and two controls. Initial results indicate that the model is effective in assessing the level of inflammation in patients.

The second generation of the device using flexible imaging fiber bundles has been designed and is under construction. In the new design, an imaging bundle replaces a set of optical fibers. Instead of yielding an output reading from each fiber sequentially, the device will use a CCD camera to record light distribution instantaneously. The new design offers two advantages over the existing device: shortening of the acquisition time and higher spatial resolution.

Monitoring Blood Circulation in Kaposi’s Sarcoma and Complex Regional Pain Syndrome Type I
Hattery, Hekmat, Gabel, Togioka, Gandjbakhche; in collaboration with Yarchoan, Dionne
We are investigating the use of three imaging modalities to quantify different parameters associated with blood circulation. The modalities are thermography, which provides a two-dimensional image of superficial skin temperatures and is based on the concept that higher temperatures occur in the skin superficial to veins that are involved in active transport of blood; laser Doppler imaging (LDI), which produces two-dimensional images of blood flow over a defined area at 690nm and 780nm; and hyperspectral imaging, which, designed in our unit, produces two-dimensional images at six wave lengths (700–1000nm) by using differential absorption algorithm (also devised by our unit) parameters related to the oxy-deoxy-hemoglobin ratio (i.e., oxygenation) and permits derivation of total blood content. Two studies are under way; the first deals with the skin disease Kaposi’s sarcoma (KS) and the second with reflex sympathetic disorder (RSD). An NCI-sponsored clinical trial is evaluating the effectiveness of anti-angiogenetic drug treatment for KS. Because KS is a highly vascular tumor, angiogenesis and capillary permeability can play an important role in the development and progression of the disease. No noninvasive standard technique is available to assess the effect of anti-angiogenetic therapy on blood flow in KS. The purpose of the clinical trial is to investigate the applicability of the three noninvasive methods for the assessment of vascularity and vascular changes associated with KS. Eighteen patients have been investigated so far. A comparative image analysis of thermography, between the lesion and contralateral, lesion-free sites, shows that the temperature of the lesion sites is different from that of the contralateral side. Similar relationships are also observed in laser Doppler images. Preliminary results indicate that the techniques are useful for assessing vascularity and vascular changes associated with KS. Completion of the ongoing study should provide additional data to support the initial results.

RSD, currently known as Complex Regional Pain Syndrome (CRPS), is a chronic pain disorder involving the sympathetic nervous system. An NIDCR/NINDS clinical study is evaluating the response of patients experiencing CRPS type I to the drug Neurotropin. In this study, the nature of chronic neuropathic pain is assessed by asymmetric thermal pattern between pain and contralateral pain-free sites; comparisons between the site of pain and the corresponding contralateral side near surface blood flow; and sympathetic response of blood flow measured by LDI as well as by temperature patterns in pain and pain-free sites following cold stimulation. As an ongoing clinical trial, results have not been unblinded, and the effect of the drug compared with the placebo may not be assessed with the preliminary results.