The diagnostic challenge of lack of choline level elevation on 1H-MR spectroscopy in grade II-III gliomas

The accurate diagnosis of brain tumour is very important in modern neuro-oncology medicine. Magnetic resonance spectroscopy (MRS) is supposed to be a promising tool for detecting cancerous lesions. However, the interpretation of MRS data is complicated by the fact that not all cancerous lesions exhibit elevated choline (Cho) levels. The main goal of our study was to investigate the lack of Cho_lesion/Cho_ref elevation in the population of grade II-III gliomas.

89 cases of gliomas grade II and III were used for the retrospective analysis – glioma (astrocytoma or oligodendroglioma) grade II (74 out of 89 cases [83%]) and III (15 out of 89 cases [17%]) underwent conventional MRI extended by MRS before treatment. Histopathological diagnosis was obtained either by biopsy or surgical resection. Gliomas were classified to the group of no-choline elevation when the ratio of choline measured within the tumour (Cho_lesion) to choline from NABT (Cho_ref) were equal to or lower than 1. Significant differences were observed between ratios of Cho_lesion/Cr_lesion calculated for no-choline elevation and glial tumour groups as well as in the NAA_lesion/Cr_lesion ratio between the no-choline elevation group and glial tumour group. With consistent data concerning choline level elevation and slightly lower NAA value, the Cho_lesion/NAA_lesion ratio is significantly higher in the WHO II glial tumour group compared to the no-choline elevation cases (p < 0.000).

In the current study the results demonstrated possibility of lack of choline elevation in patients with grade II-III gliomas, so it is important to remember that the lack of elevated choline levels does not exclude neoplastic lesion.