TY - JOUR T1 - Proton MR Spectroscopic Evaluation of Suspicious Brain Lesions After Stereotactic Radiotherapy JF - American Journal of Neuroradiology JO - Am. J. Neuroradiol. SP - 1316 LP - 1324 VL - 22 IS - 7 AU - Heinz–Peter Schlemmer AU - Peter Bachert AU - Klaus K. Herfarth AU - Ivan Zuna AU - Jürgen Debus AU - Gerhard van Kaick Y1 - 2001/08/01 UR - http://www.ajnr.org/content/22/7/1316.abstract N2 - BACKGROUND AND PURPOSE: The radiologic assessment of suspicious brain lesions after stereotactic radiotherapy of brain tumors is difficult. The purpose of our study was to define parameters from single-voxel proton MR spectroscopy that provide a probability measure for differentiating neoplastic from radiation-induced, nonneoplastic lesions.METHODS: Seventy-two lesions in 56 patients were examined using a combined MR imaging and MR spectroscopy protocol (point-resolved spectroscopy, TE = 135 ms). Signal intensities of cholines, creatines, N-acetyl aspartate, and the presence of lactate and lipid resonances were correlated to final diagnoses established by clinical and MR imaging follow-up, positron emission tomography studies, or biopsy/surgery. Statistical analysis was performed using the t test, linear discriminant analysis, and k nearest-neighbor method.RESULTS: Significantly increased signal intensity ratios ItCho/ItCr (P < .0001) and ItCho/INAA (P < .0001) were observed in neoplastic (n = 34) compared with nonneoplastic lesions (n = 32) and contralateral normal brain (n = 33). Analysis of ItCho/ItCr and ItCho/INAA data yielded correct retrospective classification as neoplastic and nonneoplastic in 82% and 81% of the lesions, respectively. Neither INAA/ItCr nor signal intensitities of lactate or lipids were useful for differential diagnosis.CONCLUSION: Metabolic information provided by proton MR spectroscopy is useful for the differentiation of neoplastic and nonneoplastic brain lesions after stereotactic radiotherapy of brain tumors. ER -