@article{oai:repo.qst.go.jp:00046732,
 author = {Saito, Shigeyoshi and Hasegawa, Sumitaka and Sekita, Aiko and Bakalova-Zheleva, Rumiana and Furukawa, Takako and Murase, Kenya and Saga, Tsuneo and Aoki, Ichio and 齋藤 茂芳 and 長谷川 純崇 and バカロバ ルミアナ and 古川 高子 and 村瀬 研也 and 佐賀 恒夫 and 青木 伊知男},
 issue = {11},
 journal = {Cancer Research},
 month = {May},
 note = {For tumor radiotherapy, the in vivo detection of early cellular responses is important for predicting therapeutic efficacy. Mn2+ is used as a positive contrast agent in manganese-enhanced MRI (MEMRI) and is expected to behave as a mimic of Ca2+ in many biologic systems. We conducted in vitro and in vivo MRI experiments with Mn2+ to investigate whether MEMRI can be used to detect cell alterations as an early-phase tumor response after radiotherapy. Colon-26 cells or a subcutaneously grafted colon-26 tumor model were irradiated with 20 Gy of X-rays. One day after irradiation, a significant augmentation of G2–M-phase cells, indicating a cell-cycle arrest, was observed in the irradiated cells in comparison with the control cells, although both early and late apoptotic alterations were rarely observed. The MEMRI signal in radiation-exposed tumor cells (R1: 0.77 +- 0.01 s−1) was significantly lower than that in control cells (R1: 0.82 +- 0.01 s−1) in vitro. MEMRI signal reduction was also observed in the in vivo tumor model 24 hours after irradiation (R1 of radiation: 0.97 +- 0.02 s−1, control: 1.10 +- 0.02 s−1), along with cell-cycle and proliferation alterations identified with immunostaining (cyclin D1 and Ki-67). Therefore, MEMRI after tumor radiotherapy was successfully used to detect cell alterations as an early-phase cellular response in vitro and in vivo.},
 pages = {3216--3224},
 title = {Manganese-Enhanced MRI Reveals Early-Phase Radiation-Induced Cell Alterations In Vivo.},
 volume = {73},
 year = {2013}
}