LOCALIZED PROTON SPECTROSCOPY OF INOPERABLE BRAIN GLIOMAS - RESPONSE TO RADIATION-THERAPY

With in vivo 1H-MRS resonances of several metabolites were simultaneou sly measured in cerebral gliomas and adjacent normal brain. 15 patient s with inoperable brain gliomas all histologically verified were monit ored with 1H-MRS and MRI before and after radiotherapy. 11 patients we re evaluable. 1H-MRS technique evolved from single volume measurements to one dimensional and two dimensional 1H spectroscopic imaging. In a ll patients N-acetyl-aspartate signals were decreased in tumour areas compared to the normal brain hemisphere. No recovery was seen after ra diotherapy. Choline signals were increased in tumour margins of high g rade gliomas and more diffusely in low grade gliomas. In 5 patients th e choline resonance decreased after radiotherapy, accompanied by a shr inkage of tumour diameter on MRI. Lactate signals were present in high grade and unspecified astrocytomas and absent in most low grade gliom as. In 3 patients the lactate signal disappeared after radiotherapy. T hese observations indicate the feasibility of 1H-MRS in monitoring met abolic responses on radiotherapy of brain gliomas.