量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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Objectives:
In management after carbon-ion radiotherapy (CIRT) in patients with non-small cell lung cancer (NSCLC, LC), differentiation of local recurrence or presence of the tumor and radiation pneumonitis (RP) is one of paramount importance for the following clinical therapeutic strategy. 18F-FDG PET/CT (FDG-PET/CT) is playing a key metabolic imaging in management of CIRT for LC patients, however PET/CT diagnosis using SUVmax parameter often encounters cases where it is difficult to distinguish between LC and RP. The aim of this study is to assess FDG-PET/CT metabolic parameters such as SUVpeak, MTV and TLG for differentiating LC and RP after CIRT.
Methods:
We retrospectively analyzed FDG-PET/CT image data of histopathologically proven 19 LC patients who were scheduled to undergo CIRT and 28 patients who were diagnosed having RP after CIRT (50.0 Gy / 1 fraction). RP was diagnosed by biopsy or by clinical follow-up more than 1 year after CIRT. Volumes of interest (VOI) on tumors were delineated using a threshold of 40% of the maximum standard uptake value (SUVmax) in each lesion. SUVmax, SUVpeak, MTV and TLG which were metabolic parameters of FDG-PET/CT were determined using an image-analysis software. Statistical analysis was performed between LC and RP using nonparametric Wilcoxon rank sum test. The diagnostic accuracy by ROC analysis was also assessed.
Results:
As a result of the test, SUVmax: LC 4.446 ± 0.552, RP 2.329 ± 0.255 (p <0.001), MTV: LC 10.59 ± 1.333, RP 46.94 ± 6.073 (p <0.0001), TLG: LC 30.66 ± 7.096, RP 63.35 ± 9.177 p <0.005), and significant differences were observed in all indices.
The area under the ROC curve (area under curve, AUC) was SUVmax: 0.80, MTV: 0.96, TLG: 0.77, and the diagnostic accuracy of MTV was the highest among these FDG-PET/CT metabolic parameters.
Conclusions:
In differentiation between NSCLC and radiation pneumonitis after CIRT, FDG-PET/CT metabolic parameters were useful, and MTV in particular would be an appropriate parameter with high diagnostic accuracy.
Differentiation between non-small cell lung cancer and radiation pneumonitis after carbon-ion radiotherapy by FDG-PET/CT metabolic parameters
