Objective: To evaluate if metabolic changes in WHO grades II and III gliomas measured in vivo with proton magnetic resonance spectroscopic imaging ((1)H-MRSI) correlate with progression-free survival (PFS).
Methods: (1)H-MRSI and MRI were performed before surgery in 61 patients with histopathological proven WHO grades II and III gliomas. Averaged (av) and maximum (max) metabolite concentrations of creatine/phosphocreatine (tCr) and choline-containing compounds (tCho) from the tumor were normalized to contralateral brain tissue. In 50 patients with a median follow-up of 34 (WHO grade II) and 19.5 (WHO grade III) months, spectroscopic data as well as the extent of tumor resection, histopathological subtype, adjuvant therapy and patients' ages were analysed for PFS times with Cox regression analysis. Kaplan-Meier method was performed with categorized tCr values (cutoff: 0.93) to estimate the median PFS time.
Results: The normalized tCr(av) was prognostic for the PFS in patients with WHO grades II and III gliomas (p<0.0001 and p=0.034, respectively). For WHO grade II gliomas, tCr(max) (p=0.008) and the patients' ages (p=0.006) were also prognostic. The multivariate analysis provided tCr(av) (p=0.001) as single independent prognostic factor for the PFS of WHO grade II gliomas. Patients with WHO grades II and III gliomas revealing a normalized tCr(av) greater than 0.93 had a significant shorter PFS.
Discussion: Potential tumor progression in WHO grades II and III gliomas is best indicated by the normalized tCr(av). Normalized tCr(av) >0.93 seems to indicate gliomas with earlier progression.