[Role of thallium SPECT for evaluating the effect of maintenance chemotherapy against malignant gliomas].

Thallium (Tl)-201 single-photon emission computed tomography (SPECT) is a useful tool for detecting brain tumors. In this study, we evaluated the utility of Tl-201 SPECT for determining the effect of maintenance chemotherapy with ACNU (nimustine hydrochloride)/VCR (vincristine sulfate) against malignant gliomas. The cases were comprised of 16 glioma cases; 6 astrocytomas, 2 anaplastic astrocytomas, and 8 glioblastomas. We first analyzed the correlation between Tl-201 uptake ratio and proliferative activity of the tumor, using Ki-67 immunohistochemistry in 13 cases of glioma. The uptake ratio of Tl-201 correlated with the Ki-67 staining indices (SI), and a closer correlation was obtained using Tl-201 delayed images than with the early images. We also analyzed the chronological changes of Tl-201 uptake ratio and volume of abnormal area evaluated by MRI T2-weighted imaging (MRI T2WI), in 10 cases of malignant glioma during maintenance chemotherapy. The Tl-201 uptake ratio gradually decreased with the effect of maintenance chemotherapy, and the sensitivity was superior to MRI findings. Together with MRI, Tl-201 SPECT is considered to be a useful indicator for evaluating the effect of maintenance chemotherapy against malignant gliomas.