Value of 1H-magnetic resonance spectroscopy chemical shift imaging for detection of anaplastic foci in diffusely infiltrating gliomas with non-significant contrast-enhancement

Objective In diffusely infiltrating gliomas (DIG), positron emission tomography (PET) imaging is a powerful method for detection of anaplastic foci. Recently, 1 H-magnetic resonance spectroscopy chemical shift imaging (CSI) using choline/creatine (Cho/Cr) or choline/N-acetylaspartate (Cho/NAA) ratios has emerged as a new non-invasive, widely available alternative. The authors therefore correlated CSI with 11 C-methionine (MET)-PET data in a series of DIG with non-significant contrast-enhancement (CE). Methods Thirty-two patients with DIG were examined with single-slice CSI on a 3 T MRI and MET-PET. Maximum pathological intratumoural ratios of CSI (=CSImax) and maximum tumour-to-normal-brain PET ratios (=PETmax; T/N ratio) were determined. Coregistration of MRI with CSI and PET was performed, and the topographic overlap of CSImax and PETmax was analysed. Histological criteria of anaplasia as well as cell proliferation rate were assessed in tumour samples inside and outside CSImax. Results CSI showed a pathological ratio in all patients, whereas PET demonstrated a pathological T/N ratio in 21/32 patients. Topographical correlation of CSImax and PETmax revealed a >= 50% overlap in 18/21 and <50% overlap in 3/21 patients, respectively. Cho/Cr-max and Cho/NAA(max) showed a >= 50% overlap in 24/32 and a <50% overlap in 8/32 patients. Cell proliferation rate was significantly higher inside than outside the CSImax (13.6% vs 6.9%, p<0.001). Conclusion The results indicate that CSI is a promising method for detection of anaplastic foci within DIG with non-significant CE. Intraoperative use of CSI by multimodal neuronavigation may increase the reliability of detection of malignant areas in glioma surgery and therefore optimise allocation of patients to adjuvant treatments.