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Objectives: Different compositions of the extra cellular matrix with changing concentrations of more or less hydrophilic components like proteins may have a major influence on the diffusion phenomena found in gliomas., Methods: 24 patients (14 male / 10 female) with histologically confirmed non necrotic glioma underwent preoperative MRI, including magnetisation transfer (MTR), triple echo T2 weighted (T2W) and diffusion weighted (DWI) sequences. Apparent diffusion coefficient (ADC), quantitative T2 and MTR maps were calculated and regions of interest (ROIs) were placed in the tumour centre (TU) and in the contralateral hemisphere (NWM). Informed consent was obtained. The study was approved by the local ethic comity., Results: Mean values evaluated in the NWM / TU were (± standard deviation); ADC: 0.78 (±0.08) × 10-3 mm2/s / 1.32 (±0.27) × 10-3 mm2/s, T2: 101.66 (±12.00) ms / 252.11 (±104.53) ms, MTR: 0.52 (±0.01) / 0.40 (±0.04). The mean value of each parameter correlated highly significant with the others (p < 0.01)., Conclusion: Our results suggest that macromolecules binding protons in their vicinity are a major determinant of proton diffusivity in brain tumours in addition to other factors such as mechanical barriers like membranes or the size of the extra-cellular space.

Objectives: T2' values reflect the presence of deoxyhaemoglobin related to high local oxygen extraction. We assessed the feasibility of T2' imaging to display regions with high metabolic activity in brain gliomas., Methods: MRI was performed in 25 patients (12 female; median age 46 years; range 2-69) with brain gliomas with additional T2 and T2* sequences. T2' maps were derived from T2 and T2*. Dynamic susceptibility weighted contrast (DSC) perfusion was performed in 12/25 patients. Images were visually assessed by two readers and five ROIs were evaluated for each patient. Pearson correlation, Mann-Whitney and Kruskal-Wallis tests were applied for statistical analysis., Results: Three patients were not further evaluated because of artefacts. Mean values of high-grade (III-IV) gliomas showed significantly lower T2' values than low-grade (II) gliomas (p < 0.001). An inverse relationship was observed between rCBV and sqr (T2') (r = -0.463, p < 0.001). No correlation was observed between T2' and rCBV for grade II tumours (r = 0.038; p = 0.875)., Conclusions: High-grade tumours revealed lower T2' values, presumably because of higher oxygen consumption in proliferating tissue. Our results indicate that T2' imaging can be used as an alternative to DSC perfusion in the detection of subtle deviations in tumour metabolism.

Background and Purpose: Diffusion tensor imaging (DTI) and MR spectroscopy are noninvasive, quantitative tools for the preoperative assessment of gliomas with which the quantitative parameter fractional anisotropy (FA) and the concentration of neurometabolites N-acetylaspartate (NAA), choline (Cho), creatine (Cr) of the brain can be determined. Measurements of FA and NAA reflect the integrity of fiber tracts and the presence of neurons, respectively. This investigation examines changes of FA and NAA and compares these different aspects in architecture of gliomas after spatial coregistration., Methods: DTI and chemical shift (1)H-MR spectroscopy was performed in 34 healthy volunteers and 69 patients with histologically confirmed (n = 48) or morphologically suspected (n = 21) non-necrotic brain glioma. Volumes of interest (VOIs) were placed in the tumor center (TC), the tumor border (TB), the normal-appearing white matter adjacent to the tumors (TNWM), and in the white matter of the contralateral hemisphere (NWMC). Median FA values and NAA/Cr and NAA/Cho ratios were calculated in the patients' VOIs and the gray and white matter of the volunteers. Correlations of FA values and NAA ratios were calculated., Results: Continuous changes of FA and NAA from the tumor center to the periphery (the adjacent white matter and the contra-lateral hemisphere, respectively) were observed, where median values were: TC: 0.73 +/- 0.45, 0.47 +/- 0.58, 0.17 +/- 0.15 (NAA/Cr, NAA/Cho, FA); TB: 1.06 +/- 0.53, 1.00 +/- 0.15, 0.23 +/- 0.08; TNWM: 1.42 +/- 2.48, 1.21 +/- 0.95, 0.34 +/- 0.09; and NWMC: 1.63 +/- 0.72, 1.56 +/- 1.34, 0.38 +/- 0.08. Correlation of median FA values and NAA ratios in the cumulative group of patients was high (r = 0.99 [NAA/Cr], 0.95 [NAA/ Cho] at P < .01). Correlation between the individual NAA ratios and the FA values was moderate (r = 0.53 [NAA/Cr], 0.51 [NAA/Cho] at P < .01)., Conclusion: In gliomas, the degree of tissue organization decreases continuously from the surrounding tissue toward the center of the tumor accompanied by a concordant decrease of NAA. This uniform behavior of FA and NAA reflects a decreasing integrity of both neuronal structures and fibers.

Purpose: To prospectively evaluate whether diffusion-tensor magnetic resonance (MR) imaging depicts differences in World Health Organization (WHO) grade II and III glial brain tumors on the basis of tumor architecture and peritumoral tract invasion., Materials and Methods: The study protocol was approved by the local ethics committee, and written informed consent was obtained. Diffusion-tensor MR imaging was performed in 23 patients (15 men, eight women; mean age, 47 years) with histologically confirmed brain gliomas. Eleven of the 23 tumors were low-grade gliomas (WHO grade II) and 12 were anaplastic gliomas (WHO grade III). Regions of interest were placed in the tumor center, tumor border, normal-appearing white matter (NAWM) adjacent to the tumor, and NAWM of the contralateral hemisphere. fractional anisotropy (FA) ratios were calculated for regions of interest in relation to the NAWM of the contralateral hemisphere. Pairwise comparisons were performed by using the Mann-Whitney U test., Results: Median FA ratios for grade II versus grade III gliomas were 0.406 versus 0.405, respectively, for tumor center, 0.733 versus 0.449, respectively, for tumor border, and 0.962 versus 0.943, respectively, for NAWM adjacent to the tumor. Differences in FA ratio between low-grade and high-grade tumors were significant in the tumor border only (P = .01). Differences in FA ratio were not significant between low-grade and high-grade gliomas in the tumor center or in the NAWM adjacent to the tumor., Conclusion: The periphery of low-grade gliomas contains a considerable amount of preserved fiber tracts. In high-grade gliomas, however, most of these tracts are disarranged. Low FA ratios in the tumor center are consistent with a high degree of disorganization of myelinated fiber tracts in the center of both low-grade and high-grade gliomas.