Spectroscopic imaging of radiation-induced effects in the white matter of glioma patients

External radiation therapy of brain tumors may cause adverse effects on nor mal brain tissue, resulting in severe neuropsychological and cognitive impa irment. We investigated the late delayed radiation effects in the white mat ter (WM) using H-1 magnetic resonance spectroscopic imaging ((HMRSI)-H-1). Nine glioma patients with local radiation-induced signal abnormalities in t he T-2-weighted MR images were studied with nine age- and sex-matched contr ols. The metabolite ratios in the radiation-induced hyper intensity area (R IHA) and in the normal appealing white matter (NAWM) of the patients were c ompared with respective WM areas of the controls. In RIHA, choline/creatine (Cho/Cr) was 17% decreased (1.22 +/- 0.13 vs 1.47 +/- 0.16, p = 0.0027, si gnificant (s), unpaired Student's t test with Bonferroni correction) in the patients compared to the controls, while there was no difference in N-acet yl aspartate/Cr (NAA/Cr) (2.49 +/- 0.57 vs 2.98 +/- 0.32, p = 0.039) or NAA /Cho (2.03 +/- 0.40 vs 2.04 +/- 0.17, p = 0.95), In NAWM, Cho/Cr was 24% de creased (1.21 +/- 0.15 vs 1.59 +/- 0.13, p < 0.0001, s) and NAA/Cho was 20% increased (2.49 +/- 0.49 vs 1.98 +/- 0.15, p = 0.0082, s) in the patients compared to the controls, while there was no difference in NAA/Cr (2.99 +/- 0.46 vs 3.16 +/- 0.32, p = 0.38). NAA(RIHA)/TAA(NAWM) was 25% decreased (0 .75 +/- 0.20 vs 1.00 +/- 0.12, p = 0.0043, s) and Cr-RIHA/Cho(NAWM) was 16% decreased (0.89 +/- 0.15 vs 1.06 +/- 0.10, p = 0.013, s) in the patients c ompared to the controls, while there was no difference in Cho(RIHA)/Cho(NAW M) (0.92 +/- 0.23 vs 0.98 +/- 0.10, p = 0.47). (HMRSI)-H-1 reveals widespre ad chemical changes in the WM after radiation therapy. In RIHA, there is lo ss of NAA, Cho, and Cr implying axonal and membrane damage and in NAWM, the re is loss of Cho, reflecting membrane damage. (C) 2000 Elsevier Science In c. All rights reserved.