The use of proton MRS in the differential diagnosis of brain tumors and tumor-like processes.

BACKGROUND: Progress in the treatment of brain neoplasms requires accurate identification of tumor type and grade, before a proper treatment plan can be implemented. The aim of our study was to investigate the use of proton magnetic resonance spectroscopy in the differential diagnosis of neoplastic brain tumors and tumor-like processes. MATERIAL/METHODS: 29 patients with ambiguous CT images of brain mass lesions were examined by MRI. 1H MRS was applied in this group as the primary option to improve differential diagnosis. In each case a routine MRI was taken in three orthogonal planes before and after i.v. administration of Gd-DTPA. 1H MRS was performed at 1.5 T using the PRESS (TE 136 ms) and STEAM (TE 20 ms) single voxel spectroscopy techniques. MRS was performed after i.v. administration of Gd-DTPA. The lesion types according to spectral patterns were compared to postoperative pathology or biopsy results. RESULTS: MRS-based diagnosis was consistent with pathology results in all cases of astrocytoma, glioblastoma and meningioma. In two cases distinguishing brain metastases from glioblastomas was difficult because of contamination of the voxel with brain tissue. Three cases of anaplastic oligodendrogliomas were misclassified as glioblastomas. In two cases MR spectra indicating an inflammatory-demyelinating process correlated with biopsy results and clinical course. CONCLUSIONS: 1HMRS proved to be a useful tool in establishing tumor type and differentiating between neoplastic and large inflammatory tumor-like lesions.