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Diffusion tensor imaging (DTI) was performed in eight patients with brain abscess (BA). The aim of this study was to see the difference in the relationship between intercellular cell adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen-1 (LFA-1) expression and DTI metrics measured in vivo in the wall and cavity of BA and its possible explanation vis-à-vis histology and immunohistochemistry. Neuroinflammatory molecules (NMs) were quantified from BA cavity aspirate of the patients and quantitative immunohistochemical analysis was performed for ICAM-1 and LFA-1 in the BA wall, showing maximal positive staining and correlated with DTI metrics. The fractional anisotropy (FA) significantly increased while mean diffusivity and spherical anisotropy significantly decreased in the BA wall compared to the BA cavity. In the BA wall, FA and linear anisotropy (CL) showed a significant positive correlation with ICAM-1 and LFA-1 expression whereas FA and planar anisotropy positively correlated with NMs quantified from aspirated pus respectively. Higher FA values in the BA wall compared to BA cavity, even when ICAM-1 and LFA-1 were expressed only in the macrophages and not in the collagen fibers, suggests that a combination of both concentric layers of collagen fibers as well as neutrophils and macrophages provide structural orientation and are responsible for increased FA. In the BA wall, increased CL was found compared to the cavity, indicating the presence of concentrically laid collagen fibers responsible for the diffusion of water molecules in the direction parallel to the collagen fibers. We conclude that in the BA, different mechanisms are operative for the changes in the DTI metrics in the wall and cavity; these conclusions are validated by histology and immunohistochemistry. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Purpose To correlate dynamic contrast-enhanced (DCE) MRI derived perfusion indices with immunohistochemically obtained vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) in a cellular fraction of brain tuberculomas (BT). Materials and Methods Thirteen BT patients underwent DCE MRI. Perfusion indices (cerebral blood volume [CBV], transfer coefficient [ktrans] and leakage [ve]) maps were generated for the quantitative analysis. The CBV was corrected for the leaky blood-brain barrier (BBB). The relative CBV (rCBV), ktrans, and ve were calculated by placing 10 regions of interest (ROIs) showing the highest values in the lesion. The percentage area of VEGF and percentage area of MMP-9 and microvessel density (MVD) were quantified from 10 fields per lesion with maximal expression of the excised BT. Pearson correlation analysis between physiological indices and quantitative VEGF, MMP-9, and MVD was performed for each ROI. Results The average value of rCBV, ktrans, ve, VEGF, MMP-9, and MVD were 3.53 ± 0.37, 2.04 ± 0.40 min−1, 0.71 ± 0.09, 12.51 ± 2.56, 18.09 ± 2.06, 10.87 ± 1.99, respectively. The ktrans ( r = 0.918, P < 0.001) and ve ( r = 0.899, P < 0.001) showed significant correlation with MMP-9, while rCBV correlated significantly with MVD ( r = 0.962, P < 0.001) and VEGF ( r = 0.868, P < 0.001). Conclusion We conclude that the expression of MMP-9, a marker of BBB disruption and disease activity in BT correlates with DCE-derived ktrans and thus has the potential to be used as its surrogate marker. J. Magn. Reson. Imaging 2008;28:588-597. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]