@article {Maj{\'o}s544, author = {C. Maj{\'o}s and C. Aguilera and J. Alonso and M. Juli{\`a}-Sap{\'e} and S. Casta{\~n}er and J.J. S{\'a}nchez and {\'A}. Samitier and A. Le{\'o}n and {\'A}. Rovira and C. Ar{\'u}s}, title = {Proton MR Spectroscopy Improves Discrimination between Tumor and Pseudotumoral Lesion in Solid Brain Masses}, volume = {30}, number = {3}, pages = {544--551}, year = {2009}, doi = {10.3174/ajnr.A1392}, publisher = {American Journal of Neuroradiology}, abstract = {BACKGROUND AND PURPOSE: Differentiating between tumors and pseudotumoral lesions by conventional MR imaging may be a challenging question. This study aims to evaluate the potential usefulness and the added value that single-voxel proton MR spectroscopy could provide on this discrimination.MATERIALS AND METHODS: A total of 84 solid brain lesions were retrospectively included in the study (68 glial tumors and 16 pseudotumoral lesions). Single-voxel spectra at TE 30 ms (short TE) and 136 ms (long TE) were available in all cases. Two groups were defined: {\textquotedblleft}training-set{\textquotedblright} (56 cases) and {\textquotedblleft}test-set{\textquotedblright} (28 cases). Tumors and pseudotumors were compared in the training-set with the Mann-Whitney U test. Ratios between resonances were defined as classifiers for new cases, and thresholds were selected with receiver operating characteristic (ROC) curves. The added value of spectroscopy was evaluated by 5 neuroradiologists and assessed with the Wilcoxon signed-rank test.RESULTS: Differences between tumors and pseudotumors were found in myo-inositol (mIns); P \< .01) at short TE, and N-acetylaspartate (NAA; P \< .001), glutamine (Glx; P \< .01), and choline (CHO; P \< .05) at long TE. Classifiers suggested tumor when mIns/NAA ratio was more than 0.9 at short TE and also when CHO/NAA ratio was more than 1.9 at long TE. Classifier accuracy was tested in the test-set with the following results: short TE, 82\% (23/28); long TE, 79\% (22/28). The neuroradiologists{\textquoteright} confidence rating of the test-cases on a 5-point scale (0{\textendash}4) improved between 5\% (from 2.86{\textendash}3) and 27\% (from 2.25{\textendash}2.86) with spectroscopy (mean, 17\%; P \< .01).CONCLUSIONS: The proposed ratios of mIns/NAA at short TE and CHO/NAA at long TE provide valuable information to discriminate between brain tumor and pseudotumor by improving neuroradiologists{\textquoteright} accuracy and confidence.}, issn = {0195-6108}, URL = {https://www.ajnr.org/content/30/3/544}, eprint = {https://www.ajnr.org/content/30/3/544.full.pdf}, journal = {American Journal of Neuroradiology} }