OBJECTIVE:The correlation between thallium-201 (201Tl) uptake, semiquantitative choline-containing compound values measured by proton magnetic resonance spectroscopy (1H-MRS), and Ki-67 labeling indexes (LIs) was investigated in three gangliogliomas.METHODS:The early and delayed201Tl indexes were calculated as the ratio of tumor to normal brain tissue uptake by201Tl single-photon emission computed tomography. Single-voxel1H-MRS was performed to measure the levels of metabolites in the tumors. Ki-67 LI was measured in the surgical specimens.RESULTS:All three gangliogliomas showed very high201Tl uptake on both early and delayed images.1H-MRS demonstrated malignancy based on the high choline peak relative to the creatine andN-acetylaspartate peaks. Ki-67 LI was less than 1% in two gangliogliomas and 3.5% in an anaplastic ganglioglioma.CONCLUSION:Both201Tl single-photon emission computed tomography and1H-MRS indicated malignancy, whereas Ki-67 LI indicated low growth activity.201Tl single-photon emission computed tomography and1H-MRS of ganglioglioma might be affected by metabolic characteristics other than growth activity.