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Macroscopic Imaging (macroscopic + imaging)
Selected AbstractsImaging of cell trafficking and metastases of paediatric rhabdomyosarcomaCELL PROLIFERATION, Issue 2 2008G. Seitz Objective:,The aim of this study was to establish a preclinical mouse model to study metastases of paediatric rhabdomyosarcoma at the macroscopic and cellular levels, with different imaging methods. Experimental Design:,The alveolar rhabdomyosarcoma cell line Rh30 was stably transfected with the red fluorescent protein (DsRed2) then was xenotransplanted (intravenous injection [n = 8], and footpad injection [n = 8]) into nude mice (NMRI nu/nu). Macroscopic imaging of metastases was performed using DsRed2-fluorescence and flat-panel volumetric computed tomography scan. In a further series of animals (n = 8), in vivo cell trafficking of rhabdomyosarcoma cells using cellular imaging with an Olympus OV100 variable-magnification small-animal imaging system was used. Results:,Metastases in the pelvis, thoracic wall and skin were visualized by fluorescence imaging. Pelvic metastases were found after tail vein injection and at other metastatic sites after footpad injection. Flat-panel volumetric computed tomography scan data allowed highly specific analysis of contrast between tumour and surrounding tissue. Correlation between fluorescence and flat-panel volumetric computed tomography scan imaging data was observed. Single-cell imaging visualized tumour cells in the vessels and demonstrated the arrest of tumour cells at vessel junctions followed by extravasation of the tumour cells. Conclusion:,We established a model for visualization of experimental metastatic invasion and describe relevant tools for imaging childhood rhabdomyosarcoma metastases at the macroscopic and cellular levels. Imaging of cell trafficking visualized the behaviour of tumour cells and development of metastases by accumulation and extravasation of rhabdomyosarcoma cells. [source] Optimizing the point spread function in phase-encoded magnetic resonance microscopyCONCEPTS IN MAGNETIC RESONANCE, Issue 1 2004A.G. Webb Abstract Three-dimensional phase-encoded magnetic resonance microscopy is the most promising method for obtaining images with isotropic spatial resolutions on the order of a few micrometers. The attainable spatial resolution is limited by the available gradient strength (Gmax) and the molecular self-diffusion coefficient (D) of the sample. In this study, numerical simulations in the microscopic-size regime are presented in order to show that for given values of Gmax and D, there exists an optimum number of phase-encoding steps that maximize the spatial resolution in terms of minimizing the full-width at half-maximum (FWHM) of the image point spread function (PSF). Unlike the case of "macroscopic" imaging, in which diffusion plays an insignificant role in determining spatial resolution, acquiring data beyond this optimal value actually degrades the image PSF. An alternative version of phase encoding, using a variable phase-encoding time rather than a variable gradient strength, is analyzed in terms of improvements in the image PSF and/or reductions in the data acquisition time for a given spatial resolution. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson 22A: 25,36, 2004. [source] Age dependence of cataract induced by ultraviolet radiation-B in miceACTA OPHTHALMOLOGICA, Issue 2007Y ZHANG Purpose: To investigate for the C57BL/6 mouse if there is an age dependence of the dose-response function for in vivo UVR-300 nm induced forward light scattering in the lens. Methods: Each of four age groups of 25 mice aged 3, 6, 12, or 24 weeks were randomly distributed on five age group specific UVR-B dose levels. The dose levels selected for each age group were derived from the expected maximum tolerable dose (MTD). Expected MTDs were set to 1.9, 3.2, 4.8, and 6.0 kJ/m^2 for the 3, 12, and 24 weeks mice, respectively, based on published data for the albino Sprague Dawley rat. Each animal was unilaterally exposed to UVR-B to the pre-determined dose, delivered during 15 minutes. All mice were sacrificed two days after exposure and both lenses were extracted for; macroscopic imaging in incident illumination against a grid and in dark-field illumination, and measurement of intensity of forward light scattering. The difference of intensity of forward light scattering between the exposed and the contralateral not exposed lens was fitted against dose received using regression based on a second order polynomial model. Results: Two days after exposure, subcapsular opacities were observed in the exposed lenses from all dose groups except at 0 kJ/m^2. In all age groups, the difference of intensity of forward light scattering increased with increasing UVR-B dose. The increase was age dependent. Conclusions: In the pigmented C57BL/6 mouse, an increasing in vivo dose of UVR-300 nm induces an increasing intensity of forward light scattering that is age dependent in the age interval 3-24 weeks. This finding should be considered in future design of experiments on UVR-effects to the mouse lens. [source] Evolution of light scattering after in vivo close to threshold dose of ultraviolet radiation 300 nmACTA OPHTHALMOLOGICA, Issue 2007S HUANG Purpose: To determine the evolution of light scattering in the albino rat lens after in vivo close to threshold UVR-300 nm. Methods: Alltogether 4 groups of 20 6 weeks old albino Sprague-Dawley rats were exposed unilaterally in vivo to 8 kJ/m2 UVR-300 nm. The animals were sacrificed at 1, 7, 48 and 336 hrs after exposure after exposure to UVR, depending on group belonging and the lenses were removed for macroscopic imaging of dark-field anatomy, and quantitative measurement of intensity of forward light scattering. Results: The intensity of light scattering increased exponentially declining with a rate constant (1/k) of 71 hrs and an asymptote maximum light scattering of 0.16 tEDC. This is consistent with findings for a dose of 30 kJ/m2 although the current time constant was higher. There was an indication of a transient increase of light scattering on the contralateral side peaking at 7 hrs after expsoure. There was an indication for some repair at 336 hrs. Conclusions: Light scattering evolves quicker, the higher the dose, but increases exponentially declining towards an assymptote. The current study suggest that observations of damage from close to threshold in vivo UVR exposure should be made at 1 week after exposure in order to detect the maximum damage. [source] | ||||||||||