Application of normoxic polymer gels in 3D-dosimetry for radiosurgery

The aim of this study was to describe the manufacture of normoxic polymer gels, to characterize their dose response relationship, to optimize MR imaging parameters in order to minimize the standard deviation in the measured dose and to use the gel in a dose verification experiment in radiosurgery. The normoxic polymer gel used is simple to manufacture under normal atmospheric conditions and is characterized by a linear dose relationship up to 40 Gy. MR imaging was performed using 2-dimensional (20) single spin echo pulse sequences with two different echo times. The imaging parameters were optimized in order to minimize the standard deviation of the measured transversal relaxation rate R2 and to achieve a geometrical resolution of 1.5 mm. Comparisons of calculated and measured relative 3D dose distributions using a multi isocentric irradiation with Gamma Knife B showed a good overall agreement of both the isodose levels and the differential and cumulative dose volume histograms. The standard deviation in the measured dose was approximately 9% at 30 Gy. The evaluation according to the gamma criterion showed that 96% of the dose voxels remained within a spatial uncertainty of 1.5 mm and a dose uncertainty of 8%.     

Cell surface bound and soluble adhesion molecules in CSF and blood in multiple sclerosis: correlation with MRI-measures of subclinical disease severity and activity.

BACKGROUND: The expression of soluble cell adhesion molecules (AM) in cerebrospinal fluid (CSF) and blood and their significance as measures of disease activity has been extensively studied in patients with multiple sclerosis (MS). In previous studies, we found that cell surface bound AM on mononuclear cells (MNC) in CSF and blood might be useful markers of clinical disease activity in MS patients. OBJECTIVE: To analyze the correlation of cell surface bound and soluble AM in CSF and blood with magnetic resonance imaging (MRI) markers of subclinical disease severity and activity in patients with MS. METHODS: Expression levels of cell surface bound AM on peripheral blood and CSF MNC were determined by flow cytometry analysis in 77 (CSF: 33) MS patients. Concentration levels of the soluble forms of AM were measured by enzyme-linked immunosorbent assay (ELISA). In corresponding cerebral gadolinium (Gd)-enhanced MRI scans, we determined both measures of subclinical disease severity and subclinical disease activity. RESULTS: The expression levels of cell surface bound AM in peripheral blood correlated inversely with parameters for subclinical disease severity and activity on cerebral MRI scans as well as with the disease duration. Furthermore, we found significant correlations between serum levels of soluble AM and patient age but not with disease duration. CONCLUSIONS: Our results suggest that subclinical disease progression may be associated with a decrease of the expression of cell surface bound AM on peripheral blood MNC. This might be a result of activated MNC migration into the CNS.