Shigeki Nagamachi MD, PhD, Presenter: Nothing to Disclose

Ryuichi Nishii MD, PhD, Abstract Co-Author: Nothing to Disclose

Youichi Mizutani, Abstract Co-Author: Nothing to Disclose

Seigo Fujita MD, Abstract Co-Author: Nothing to Disclose

Takanori Yano MD, PhD, Abstract Co-Author: Nothing to Disclose

Shozo Tamura MD, PhD, Abstract Co-Author: Nothing to Disclose

Methionine-PET is recommended in diagnosing brain tumors because of better tumor contrast than FDG-PET. However, commonly used quantitative parameter such as SUVmax shows lower values and narrower ranges compared with that of FDG. In addition, SUVmax reflect only the value of the single voxel and it does not reflect a whole tumor image. Although the utility of metabolic tumor volume (MTV) and total lesion glycolysis (TLG) in the quantitative evaluation is reported in FDG, there have been no reports regarding the methionine (MET). We compared the values of quantitative parameters between MET-PET and FDGーPET in brain tumors.

In 21 cases of brain tumor (Glioblastoma14、Oligodendroglioma4、Malignant lymphoma 2、Dysgerminoma1) , we compared the values of methionine uptake parameters with those of FDG uptake parameters and also examined the correlation of both parameters. In calculating the volume based parameters, the threshold was 40% of SUVmax. In order to avoid the influence of physiological brain uptake, voxel of interest was drawn on the three-dimensional PET/MRI fusion image. The parameter of methionine PET which corresponds to TLG of FDG-PET, we defined it as Total lesion methionine metabolism (TLMM). Both comparisons and correlations of parameters between the both examinations were analyzed.  

Both values of SUVmax and SUVpeak were significantly lower in MET compared with those of FDG (3.74 vs. 8.72 and 3.33 vs.6.86). In contrast, both values of MTV and TLMN (TLG) were significantly higher in MET compared with those of FDG (44.98ml vs. 21.52ml and 83.88 vs. 44.37). In the correlation analysis, both volume based parameters showed good correlation compared with those of SUVmax or SUVpeak (MTV: 0.78, TLG: 0.73, SUVmax: 0.4, SUVpeak: 0.32). Thus both volume-based parameters demonstrated appropriate quantitative values and also showed good correlation to those of FDG-PET parameters.

In evaluating brain tumor quantitatively by MET-PET, volume based parameter, particularly MTV, was considered to be the most relevant parameter.

Although the MET-PET is useful in evaluating brain tumor, ideal quantitative parameter had not been available. The current study demonstrated that volume based parameters were applicable for diagnosing brain tumor.

Nagamachi, S, Nishii, R, Mizutani, Y, Fujita, S, Yano, T, Tamura, S, The Usefulness of Volume Based Parameters (MTV or TLG) of Methionine PET in Brain Tumor?—Comparison Study with FDG-PET/CT.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045469.html