PT  - JOURNAL ARTICLE
AU  - Manabu Kinoshita
AU  - Hideyuki Arita
AU  - Tetsu Goto
AU  - Yoshiko Okita
AU  - Kayako Isohashi
AU  - Tadashi Watabe
AU  - Naoki Kagawa
AU  - Yasunori Fujimoto
AU  - Haruhiko Kishima
AU  - Eku Shimosegawa
AU  - Jun Hatazawa
AU  - Naoya Hashimoto
AU  - Toshiki Yoshimine
TI  - A Novel PET Index, <sup>18</sup>F-FDG–<sup>11</sup>C-Methionine Uptake Decoupling Score, Reflects Glioma Cell Infiltration
AID  - 10.2967/jnumed.112.104992
DP  - 2012 Nov 01
TA  - Journal of Nuclear Medicine
PG  - 1701--1708
VI  - 53
IP  - 11
4099  - http://jnm.snmjournals.org/content/53/11/1701.short
4100  - http://jnm.snmjournals.org/content/53/11/1701.full
SO  - J Nucl Med2012 Nov 01; 53
AB  - The linear correlation between 11C-methionine PET and tumor cell density is not well conserved at the tumor border in glioma. A novel imaging analysis method, voxelwise 18F-FDG–11C-methionine PET decoupling analysis (decoupling score), was evaluated to determine whether it could be used to quantitatively assess glioma cell infiltration in MRI-nonenhancing T2 hyperintense lesions. Methods: Data collection was performed in a prospective fashion. Fifty-four MRI-nonenhancing T2 hyperintense specimens were stereotactically obtained from 23 glioma patients by intraoperative navigation guidance. The decoupling score and tumor–to–normal tissue (T/N) ratio of 11C-methionine PET were calculated at each location. Correlations between the tumor cell density at these lesions, decoupling score, and T/N ratio of 11C-methionine PET were then evaluated. Results: Both the decoupling score and the T/N ratio showed a linear correlation with tumor cell density at these specimens (R2 = 0.52 and 0.53, respectively). Use of the decoupling score (cutoff = 3.0) allowed the detection of specimens with a tumor cell density of more than 1,000/mm2, with a sensitivity and specificity of 93.5% and 87.5%, respectively, whereas conventional 11C-methionine PET (cutoff = 1.2 in T/N ratio) was able to detect with a sensitivity and specificity of 87.0% and 87.5%, respectively. Reconstructed images (decoupling map) using the decoupling score enabled the visualization of glioma lesions that were difficult to visualize by 11C-methionine PET alone. Conclusion: The decoupling score showed better performance in detecting glioma cell infiltration than 11C-methionine uptake alone, thus suggesting that 18F-FDG–11C-methionine uptake decoupling analysis is a powerful imaging modality for assessing glioma invasion.