[Can proton magnetic resonance spectroscopy be of any value as a prognostic factor in medulloblastoma?]

Proton MR spectroscopy (MRS) is a noninvasive chemical analysis of metabolites in brain tissue. Metabolite ratios are useful because age dependant normal values are known and differ significantly from the values obtained in various diseases of brain tissues.

The aim of our study was to evaluate whether MRS correlates with magnetic resonance imaging (MRI), course of disease, pathology of resected tumours after preoperative chemotherapy and can be of prognostic value in patients with medulloblastoma (MB).

Eight patients with histologically proven MB were studied. All patients underwent MRS and MRI at diagnosis and after neoadjuvant chemotherapy consisting of VCR,VP,CTX,CBCA. Preoperative chemotherapy was followed by surgery, radiotherapy and maintenance chemotherapy. Assessment whether MRI correlates with MRS after preoperative chemotherapy was performed. Additionally MRS was correlated with the course of disease and pathology results.

Out of 8 patients 5 had partial remission of their tumours on MRI. Two of them had favorable reaction on MRS defined as elevation of NAA and Cr decrease in Cho,Lac/Lip. Both are alive and disease free. In 2 patients no changes, compared with MRS at diagnosis were found. Both died of the disease. One had an indistinct positive change and died. Stabilization on MRI was observed in 1 patient, who also had a good reaction on MRS. He is alive, disease free. Two patients had disease progression on MRI. Both had poor reaction on MRS, one died, one is alive with disease. It was noticed that good response on MRS correlated with chemotherapy induced tumour changes observed in pathology specimens from resected tumours. Small number of patients does not allow to draw conclusions but our results signal that MRS might be of prognostic value in brain tumours.