Dear Editor, We read with attention the article "Evaluation of glioma proliferation by 99 mTc-Tetrofosmin" by Alexiou et al. (Neuro-Oncology 2008;10:104-105). We have significant experience in the use of single-photon emission computed tomography (SPECT) images in the management of malignant glioma patients. 1-3 In our opinion, the published study was too small and underestimated the implications of SPECT images in the management of glioma patients. We would like to clarify this subject by sharing some of our own experiences. Tetrofosmin scintigraphy has characteristics similar to those of technetium-99m-labeled methoxyisobutylisonitrile (99 mTc-MIBI) scintigraphy. Moreover, its sensitivity and specificity in distinguishing malignant lesions from benign tumors and in discriminating recurrent glioma from radionecrosis are the same as those of 99 mTc-MIBI scintigraphy. 2 Moreover, tetrofosmin could be used as a noninvasive marker of glioma proliferative activity, like the sestamibi tracer, but the clinical utility of tetrofosmin needs to be evaluated. 4 We point out the following: