Imaging with 3′-deoxy-3′-18F-fluorothymidine (18F-FLT) positron emission tomography (PET) can provide tumor-specific details accurately and noninvasively in patients with gliomas, as demonstrated by two studies appearing in the December 2012 issue of The Journal of Nuclear Medicine.

In one study (2012;53[12]:1911-1915), researchers retrospectively evaluated 18F-FLT uptake in patients with gliomas, and correlated the results with tumor grade and proliferative activity. Of the 56 patients involved, 36 had newly diagnosed gliomas and 20 had recurrent gliomas.

An analysis of tissue specimens revealed a significant difference in tumor-to-normal ratio among different grades of newly diagnosed gliomas and between low- and high-grade newly diagnosed and recurrent gliomas. 18F-FLT uptake correlated more strongly with the proliferative activity in newly diagnosed gliomas than in recurrent gliomas, leading the authors to conclude that 18F-FLT PET seems to be useful in the noninvasive assessment of grade and proliferation in gliomas, particularly in newly diagnosed tumors.

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The other study (2012;53[12]:1904-1910) involved 26 patients with suspected high-grade gliomas who underwent preoperative 18F-FLT PET/computed tomography (CT) and T1-weighted magnetic resonance imaging (MRI) of the brain after contrast application. The investigators calculated the maximum standardized uptake value and used three different PET segmentation methods to estimate the proliferative volume. They then assessed the maximum standardized uptake value and the different methods to estimate proliferative volume for overall survival.

Median overall survival among the study subjects was 397 days, with 19 deaths occurring during that period. The proliferative volume as determined by 18F-FLT PET was associated with overall survival in high-grade malignant gliomas. The researchers found that the method of signal-to-background ratio for an adaptive threshold delineation yielded the best results to predict short and long overall survival in persons with gliomas.