A preliminary study of murine walker-256 tumor hypoxia detected by blood oxygen level dependent-MR / 中华放射学杂志

ABSTRACT

Objective To establish Walker-256 transplantation tumor model in SD Rats.To study of R2 * signal changes on murine Walker-256 tumor after inhaling Carbogen by blood oxygen level dependent (BOLD)-MR,and to explore the feasibility of BOLD-MRI on detecting tumor hypoxia.Methods Walker-256 tumor cell implanted subcutaneously in right lower abdomen of 95 female SD rats.MR was performed on the tumor-forming rats when the maximum diameter of tumor reached 1-3 cm,using a 3.0 T MR scanner equipped with a 3 inch animal surface coil BOLD-MRI was done by using a multiecho SPGR sequence during inhaling air and at 10 minute after inhaling Carbogen,respectively.All images were transferred to GE ADW 4.3 workstation,then a baseline R2* (R2 * a) and R2 * (R2 * b) after inhaling Carbogen of tumor was calculated using R2 Star analysis software and △R2 * was calculated through △R2 * =R2 * b-R2 * a,meanwhile the volume of tumor were calculated as well.The difference of R2 * signal preand post-inhaling of Carbogen was compared with a paired t test,Pearson correlation was calculated between R2 * a,△R2 * and the volume of tumor,respectively.The correlation between △R2 * and R2 * a was also assessed by Pearson correlation.Results Sixty-eight of ninety-five female SD rats formed the tumor (71.6％).The volume of tumor was from 352 to 13 173 mm3.Mean △R2* decreased significantly (-2.26 ±3.90) s-1 from (41.18 ±22.29) s-1 during breathing air to(38.91 ±21.35) s-1 10 min after inhaling Carbogen (t =4.01,P ＜ 0.01).△R2 * was inversely correlated with R2 * (r =-0.32,P ＜ 0.05).The △R2 * was well correlated with volume of tumor (r =0.35,P ＜ 0.05),but R2 * a was not correlated with volume of tumor(r =-0.03,P ＞ 0.05).Conclusions BOLD-MRI can detect the R2 * signal change of murine Walker-256 tumor pre-and post-inhaling of Carbogen.The R2 * signal showed significant decrease after inhaling Carbogen,however,the individual variation was remarkable.