ESPECTROSCOPIA POR RESONANCIA MAGNÉTICA. SU VALOR DIAGNÓSTICO EN LESIONES CEREBRALES TUMORALES Y PSEUDOTUMORALES Artículo originasl

SUMMARY Purpose: To assess diagnostic capability of MR spectroscopy (MRS) to differentiate between brain tumor and tumorlike lesions using Naa/Cr and Cho/Cr index. Method and materials: From October 2000 to November 2002 we studied 17 patients suspected of having primary or recurrent brain tumor with monovoxel MRS. Peaks heights and Naa/Cr and Cho/Cr index were determined. Naa/Cr index equal or minor to 1.30 and Cho/Cr index equal or major to 0.80 were considered abnormal. Final diagnosis was obtained by surgical resection (12 cases) and clinical follow up (5 cases). Patients were divided in two groups. Group A included 9 patients with previous surgical proved brain glioma, 6 of which received additional radium therapy. Group B included 8 patients with clinical suspected brain tumor without previous evidence of neoplastic disease. Statistic analysis and distribution of studied population was done. We determined Se, Sp, PPV and NPV for each group and independent variable considered. Results: Group A: Naa/Cr index accurately predicted diagnosis in 8 of 9 cases (Se 86%, Sp 100%, PPV 100%, NPV 67%). Cho/Cr index accurately predicted final diagnosis in all cases. Group B: Naa/Cr index accurately predicted diagnosis in 7 of 8 cases (Se 86%, Sp 100%, PPV 100%, NPV 50%). Cho/Cr index accurately predicted final diagnosis in all cases. Considering both groups there were 14 malignant and 3 benign lesions. In neoplastic conditions mean value was 0.90 (+/- 0.16) for Naa/Cr index and 1.65 (+/- 0.37) for Cho/Cr index.