RESUMO
PURPOSE: Thallim-201 (201Tl) brain SPECT and proton (1H) magnetic resonance spectroscopy (MRS) have been used to evaluate tumor grade and viability of glioma. We assessed the correlations between 201Tl brain index or spectrum of metabolites of 1H MRS and grade of glioma or histopathologic findings. MATERIALS AND METHODS: We studied 17 patients (4 astrocytoma, 7 anaplastic astrocytoma and 6 glioblastoma). On 201Tl Brain SPECT, 201Tl index was measured as the ratio of average counts for region of interest to those for the contralateral normal brain. On 1H MRS, we calculated choline (Cho) /creatine (Cr) ratio and N-acetylaspartate (NAA)/Cr ratio in ROI defined as tumor center. Histopathologic findings were graded by Ki-67 index, cellularity, mitosis, pleomorphism, necrosis and endothelial proliferation. An unpaired t test and statistical correlations were performed to evaluate these data. RESULTS: Tl-index showed the best correlation with Ki-67 index (p<0.01), less correlations with cellularity, mitosis, and endothelial proliferation, but no correlation with results of MRS, pleomorphism, or necrosis. The findings of MRS did not correlate with all of the above. The cases of glioblastoma demonstrated a higher Tl-index, Cho/Cr ratio, Ki-67 index and lower NAA/Cr ratio, albeit without statistical significance. CONCLUSION: Even though 201Tl brain SPECT did not correlate directly with grade of malignancy, it may still be useful in determining biological aggressiveness of tumor and prognosis of patients because it correlated well with Ki-67 index, a growth fraction of glioma, cellularity, mitosis and endothelial proliferation.