gms | German Medical Science

Objective: Today anatomic MRI is the method of choice for the detection and diagnosis of intrinsic brain tumors. The main limiting factor of the conventional MRI is the lack of metabolic information. Proton MR spectroscopy (MR-S) on the other hand provides metabolic information, though clinical value of the information regarding tumor grading and survival in patients with cerebral gliomas is controversial. With this study we aim to assess the value of MR-S concerning tumor grading and survival.

Method: Patients harboring gliomas who received a MR-S and tumor resection or biopsy were included in this study. 3D 1H-MR spectroscopy (PRESS, TR: 1669 ms, TE: 288 ms, FOV: 200 (ap) x 176 (rl) x 72 (fh) mm, 10 mm isovoxel, acquisition time: 15:55 min) covered the tumor, the peritumoral edema and the contralateral healthy hemisphere. Post-processing was performed on an extended MR workspace workstation (Philips Medical, the Netherlands). Residual water subtraction, apodization filtering, zero filling, and fusion with the anatomical data were done with the software, SpektroView (Philips Medical Systems). All metabolite ratios were described as regional ratios in comparison with healthy contralateral hemispheres. Clinical data, tumor entity, further therapy, extent of resection and overall survival were recorded. Mann-Whitney U test and ROC analysis were used for assessing the usefulness for tumor grading. Univariate and multivariate cox regression were conducted for survival analysis.

Results: 103 patients were included (WHO II = 16, WHO III = 18, WHO IV = 69, 44 = f, 59 =m). Mean age was 55 years (22 to 83 years). 49 patients received a complete tumor resection, 32 patients a resection > 90%, 10 patients > 50% and 11 patients a biopsy only. NAA/Cr-ratios significantly correlated with tumor grade (III vs. IV; p<0.02). For the differentiation of low-grade vs. high-grade gliomas the Cho/Cr-ratio proved to be statistically significant (p<0.01). The NAA/Cr-, Cho/Cr-, and Cho/NAA-ratios were statistical significant concerning the overall survival in univariate analysis. Regarding the multivariate analysis and overall survival age, extent of resection, preoperative KPS and Cho/NAA ratio (maximum) proved to be significant (p=0.05).

Conclusions: Proton magnetic resonance spectroscopic imaging enables grading of cerebral gliomas and has a predictive value regarding the overall survival of patients harboring cerebral gliomas.

Note: Iwona Krzyzanowska and Jens Gempt contributed equally.