IN-VIVO SINGLE-VOXEL PROTON MR SPECTROSCOPY IN INTRACRANIAL CYSTIC MASSES

PURPOSE: Our objective was to evaluate the proton MR spectroscopic pat tern of the cystic contents of various intracranial masses and to repo rt characteristic spectral patterns that may be helpful in the differe ntial diagnosis of these lesions, METHODS: We evaluated 40 proton MR s pect-ra obtained from cystic contents of various intracranial cystic m asses in 39 patients, including gliomas (n = 14), metastases (n = 3), abscesses (n = 8), cysticercosis (n = 4), epidermoids (n = 3), and oth ers (n = 7). Proton MR spectroscopy was performed on a 1.5-T MR unit u sing a point-resolved spectroscopic sequence with a 2 x 2 x 2 cm(3) vo lume of interest, Assignment of the resonance peaks was based on previ ous studies,RESULTS: Adequate proton MR spectroscopic data were obtain ed in 35 cases (88%), In most gliomas and metastases, only a lactate r esonance was observed, There was a trend toward a higher lactate peak in high-grade gliomas, A few tumors, including malignant gliomas and m etastases, showed lipid signal combined with lactate signal, In absces ses, there were various combinations of lactate, acetate, succinate, a mino acids (including valine, alanine, and/or leucine), and/or unassig ned resonances, In cysticercosis, resonances of lactate, succinate, al anine, acetate, and/or unassigned resonances were observed, Three epid ermoid cysts showed only lactate signal, There were no identifiable re sonances from the arachnoid and porencephalic cysts, CONCLUSION: Only lactate is commonly observed in a variety of intracranial cystic masse s, except for abscess and cysticercosis, in which resonances of acetat e, succinate, amino acids, and/or unassigned metabolites can be seen i n addition to a lactate peak.