In vivo monitoring of vascularization and oxygenation of tumor xenografts using optoacoustic microscopy and diffuse optical spectroscopy.

The research is devoted to comparison of the blood vessel structure and the oxygen state of three xenografts: SN-12C, HCT-116 and Colo320. Differences in the vessel formation and the level of oxygenation are revealed by optoacoustic (OA) microscopy and diffuse optical spectroscopy (DOS) respectively. The Colo320 tumor is characterized by the highest values of vessel size and fraction. DOS showed increased content of deoxyhemoglobin that led to reduction of saturation level for Colo320 as compared to other tumors. Immunohistochemical (IHC) analysis for CD31 demonstrates the higher number of vessels in Colo320. The IHC for hypoxia was consistent with DOS results and revealed higher values of the relative hypoxic fraction in Colo320.

Physical and computer-based modeling in internal temperature reconstruction by the method of passive acoustic thermometry.

The purpose of this work was to investigate experimentally the capacity of passive acoustic thermometry (PAT) for the reconstruction of 1D, time-variable distributions of the internal temperature. Because in the PAT a noise signal is measured, a considerable integration time (about one minute) is required to attain an acceptable error level (0.5-1K). To optimize the time, an algorithm was proposed to take account of the fact that the temperature satisfied the heat equation. The problem was reduced to that of determining two parameters (initial temperature and thermal diffusivity) of the object under study. The desired parameters were considered constant and were not determined anew after each measurement; instead, their values were refined using all the previous measurements. The proposed algorithm was tested experimentally (where the temperature was reconstructed in a model object, a slab of polytetrafluoroethylene) and investigated by means of computer modeling. The duration of one measurement was about 5.5s. As a result, an error of the temperature reconstruction of about 0.5K, acceptable for medical applications, was attained after 30-60s (depending on the depth) from the beginning of the measurements. After that, temperature distributions can be reconstructed after each measurement without loss of the reconstruction accuracy. The proposed method can be used to control the temperature under a local hyperthermia, lasting 1 min and more, of the human body.

[Laser hyperthermia of tumors with the use of golden nanoparticles under the control of optical coherent tomography and acoustothermometry].

The local laser hyperthermia of an experimental tumor RShM-5 of mice with the use of golden plasmin resonance nanoparticles has been carried out. The accumulation of particles in the tumor was controlled by the in vivo noninvasive method of optical coherent tomography. Using this method, the time of the maximum content of nanoparticles in the tumor was determined to be 5 h after the intravenous administration during which the laser hyperthermia was performed. The control of the tumor temperature during the hyperthermia seance showed that the application of nanoparticles provides an effective temperature elevation inside the node and a more targeted heating. The local laser hyperthermia with nanoparticles induced the inhibition of the tumor growth from day 5 to day 7 after the seance with a maximum value of 56%.