Myo-inositol: a marker of reactive astrogliosis in glial tumors?

In a prospective study, two-dimensional (1)H-MRS with TE of 30 ms was performed before surgery in 56 patients with glial brain tumors. Concentrations of myo-inositol (MI), trimethylamine (TMA) and creatine/phosphocreatine (tCr) were evaluated for the whole tumor and scaled to the normal-appearing contralateral brain tissue. To assign changes in MI to specific tissue pathology, the normalized peak and mean concentrations of MI were correlated with TMA and tCr concentrations. TMA is accepted as a marker of proliferating tumor tissue, and tCr might be a marker of reactive astrogliosis. The mean and peak concentrations of MI and tCr correlated positively (r = 0.7), but not the concentrations of MI and TMA. The absolute concentration of MI was significantly increased in all tumor tissues (5.55 +/- 2.92 mM; mean +/- SD) compared with the normal-appearing white matter (4.33 +/- 1.22 mM, p = 0.005), with the highest concentrations for gliomatoses (n = 10) and grade II oligoastrocytomas (n = 3). Significant differences (P = 0.004) between low- and high-grade astrocytomas were found for TMA (1.67 +/- 0.32 mM and 2.65 +/- 0.86 mM, respectively), but not for MI (5.92 +/- 1.98 mM and 5.49 +/- 3.27 mM, respectively). As increased MI and tCr concentrations were found in gliomatosis and other cerebral diseases associated with marked astrogliosis, this process may also be responsible for the observed changes in MI in other glial tumors. Copyright (c) 2007 John Wiley & Sons, Ltd.