Correlation of 40-[methyl-11C]-Thiothymidine Uptake with Ki-67 Immunohistochemistry in Patients with Newly Diagnosed and Recurrent Gliomas

Purpose: 40-[methyl-11C]-thiothymidine (4DST) has been developed as an in vivo cell proliferation marker based on the DNA incorporation method. We evaluated 4DST uptake on PET in patients with newly diagnosed and recurrent gliomas and correlated the results with proliferative activity. Methods: 4DST PET was investigated in 32 patients, including 21 with newly diagnosed gliomas and 11 with recurrent gliomas. PET imaging was performed at 15 min after 4DST injection. The standardized uptake value (SUV) was determined by region-of-interest analysis. The maximal SUV for tumor (T) and the mean SUV for contralateral normal brain tissue (N) were calculated and T/N ratio was determined. Proliferative activity as indicated by the Ki-67 index was estimated in tissue specimens. Results: The sensitivity of 4DST PET for the detection of newly diagnosed and recurrent gliomas was 86 % and 100 %, respectively. In newly diagnosed gliomas, there was a weak correlation between T/N ratio and Ki-67 index (r1⁄4 0.45; p< 0.05). In recurrent gliomas, there was no significant difference between T/N ratio and Ki-67 index. Conclusion: In newly diagnosed gliomas, 4DST PET seems to be useful in the noninvasive assessment of proliferation.