Utility of respiratory-gated small-animal PET/CT in the chronologic evaluation of an orthotopic lung cancer transplantation mouse model

Our aim in this study was to clarify the effects of respiratory-gated PET in the evaluation of lung cancer according to the 18F-FDG uptake in an orthotopic transplantation mouse model. We created such a model, and we performed PET/CT. The mice were divided into two groups according to tumor volume: a small-tumor group (<20 mm3) and a large-tumor group (>20 mm3). We reconstructed the following conditions based on list-mode data: non-gated (3D) images and gated (4D) images, divided based on the respiratory cycle (expiration phase, stable phase, and inspiration phase). We calculated the maximum standardized uptake values (SUVmax) in each phase. We used the % difference [= (4D SUVmax – 3D SUVmax)/3D PET SUVmax × 100 (%)] to evaluate the differences in the 4D SUVmax and 3D SUVmax. The 4D SUVmax values were significantly higher than the 3D SUVmax, regardless of the tumor size. The % difference for the small tumors was greater than that for the large tumors, and it was highest in the stable phase. We conclude that the SUVmax in the stable phase under respiratory-gated PET are the most reliable. The SUVmax observed under non-gated PET are considered to be more frequently underestimated in cases involving small tumors than in those involving large tumors. In the chronologic study evaluating the time course of tumor development, the size of the tumor is small in early stage, and respiratory-gated PET is effective in reducing the underestimation of such tumors caused by respiratory motion.

内容要旨・審査要旨・論文本文の公開:
内容要旨 : LID201606131007.pdf
審査要旨 : LID201606131008.pdf
論文本文 : LID201704171011.pdf
著者の申請により要約(2016-06-13公開)に替えて論文本文を公開(2017-04-17)
本論文は, 著者Tamaki Otaniの学位論文として提出され, 学位審査・授与の対象となっている。
The final publication is available at Springer via https://doi.org/10.1007/s12194-015-0316-3