An experimental setup for multicolor frequencydomain diffuse optical tomography (FD DOT) was created to visualize neoplasia of breast tissue and to estimate its size. The breast is gently pressed between two glass plates and scanned in the transilluminative configuration by a single source and detector pair. Illumination at three wavelengths (684 nm, 794 nm, and 850 nm) which correspond to different parts of the absorption spectrum in a therapeutic transparency window provides information about concentration of the main absorbers (oxygenated hemoglobin, deoxygenated hemoglobin, and fat/water). Source amplitude modulation at 140 MHz increases spatial resolution and provides separate reconstruction of scattering and absorption coefficients. Moreover, it gives information about breast thickness, which is important for reconstruction. The sensitivity of the system enables one to detect the light propagated through tissue having thickness up to 8 cm. Studies on model media and preliminary in vivo experiments with normal breast and breast carcinoma were performed. An increase of scattering coefficient and total hemoglobin concentration is observed in the tumor area. This corroborates validity of the FD DOT method for breast cancer diagnosis.Examination couch equipped with FD DOT device in the Semashko Regional Hospital (Russia)

The non-invasive measurement of blood oxygen saturation in blood vessels is a promising clinical application of optoacoustic imaging. Nevertheless, precise optoacoustic measurements of blood oxygen saturation are limited because of the complexities of calculating the spatial distribution of the optical fluence. In the paper error in the determination of blood oxygen saturation, associated with the use of approximate methods of optical fluence evaluation within the blood vessel, was investigated for optoacoustic measurements at two wavelengths. The method takes into account both acoustic pressure noise and the error in determined values of the optical scattering and absorption coefficients used for the calculation of the fluence. It is shown that, in conditions of an unknown (or partially known) spatial distribution of fluence at depths of 2 to 8 mm, minimal error in the determination of blood oxygen saturation is achieved at wavelengths of 658 ± 40 nm and 1069 ± 40 nm.

A fluorescence diffuse tomography (FDT) setup for monitoring tumor growth in small animals has been created. In this setup an animal is scanned in the transilluminative configuration by a single source and detector pair. To remove stray light in the detection system, we used a combination of interferometric and absorption filters. To reduce the scanning time, an experimental animal was scanned using the following algorithm: (1) large-step scanning to obtain a general view of the animal (source and detector move synchronously); (2) selection of the fluorescing region; and (3) small-step scanning of the selected region and different relative shifts between the source and detector to obtain sufficient information for 3D reconstruction. We created a reconstruction algorithm based on the Holder norm to estimate the fluorophore distribution. This algorithm converges to the solution with a minimum number of fluorescing zones. The use of tumor cell lines transfected with fluorescent proteins allowed us to conduct intravital monitoring studies. Cell lines of human melanomas Mel-P, Mel-Ibr, Mel-Kor, and human embryonic kidney HEK293 Phoenix were transfected with DsRed-Express and Turbo-RFP genes. The emission of red fluorescent proteins (RFPs) in the long-wave optical range permits detection of deep-seated tumors. In vivo experiments were conducted immediately after subcutaneous injection of fluorescing cells into small animals.

Photodynamic therapy (PDT) has been successfully used in clinical practice for decades; however, clinical outcome data are not always consistent resulting in a great necessity for real-time monitoring to predict the therapy outcome.In a retrospective clinical study, 402 patients with non-melanoma skin malignancies were enrolled who underwent PDT treatment and fluorescence real-time imaging. The photosensitizer used was a chlorine e6 derivative (FotoditazinBaseline

No abstract

Photodynamic therapy is one of the most promising methods for the treatment of oncological, inflammatory and degenerative diseases of the skin. This technique is based on light irradiation of a photosensitizer that has been injected into the patient's body prior to the procedure, with determination of the efficacy of treatment requiring proper assessment of the drug concentration in the tissue lesion and the extent of sensitizer photobleaching during irradiation. We have developed a compact and low cost device based on a fluorescence imaging for localizing the tumor in the patient's body, tracking the position of the tissue lesion during involuntary movements of the patient, estimating accumulation of the sensitizer in the tumor relative to the surrounding tissues and monitoring photobleaching of the sensitizer during laser irradiation. The system that has been created is compatible with any therapeutic laser and includes a single CCD camera and two LEDs, one in the excitation band and the other in the emission band of the 'Photoditazin' sensitizer. In this letter we also present the test results of the device in model experiments and in preliminary clinical trials. The results obtained clearly show the efficacy of the system for monitoring sensitizer photobleaching during photodynamic therapy.

The dispersion of biotissue optical properties results in distortion of the spectrum of radiation during propagation through biotissues. This phenomenon can be used for solving the inverse problem in fluorescence diffuse tomography. We have developed the spectrally resolved fluorescence diffuse tomography (SFDT) technique, which allows reconstruction of the spatial distribution of the fluorophore in biotissue even in the presence of unknown autofluorescence. The experimental setup combining epi-illumination and trans-illumination imaging geometries with spectral resolution has been created. Experimental studies on tissue phantoms and small animals in vivo with the proposed SFDT technique have been conducted. The obtained results have shown high accuracy of the inverse problem solution for spatial distribution of fluorophore concentration.

Quantum dots (QD) are a new class of fluorescence labels with properties and biomedical applications that are not available with traditional organic dyes and fluorescent proteins. The unique optical properties of QDs (high absorption, quantum yield and emission spanning to near IR) make them attractive as in vivo markers for deep-tissue imaging. Different types of optical tomography allow imaging of fluorescent-labeled tumors located deep in human or animal tissue. In this work, preliminary results of the fluorescent diffuse tomography (FDT) method in application to CdTe/CdSe-core/shell fluorescing nanocrystals are reported. In our experiments we utilized low-frequency amplitude modulation (1 kHz) of the second harmonic of Nd:YAG laser (532 nm). The transilluminative configuration was used in the setup. Results of post mortem experiments with capsules containing QDs placed into esophagus of small animals to simulate labeled tumor are shown. An algorithm of processing fluorescent image based on calculating zero of maximum curvature has been applied to detect fluorescent inclusions boundaries on the image. This work demonstrates potential capabilities of the FDT method for imaging of deep fluorescent tumors in human tissue or animal models of human cancer.Intensity, a.u.