A prospective clinical trial of tumor hypoxia imaging with 18f-fluoromisonidazole positron emission tomography and computed tomography (f-miso pet/ct) before and during radiation therapy

To visualize intratumoral hypoxic areas and their reoxygenation before and during fractionated radiation therapy (rt),18f-fluoromisonidazole positron emission tomography and computed tomography (f-misopet/ct) were performed. a total of 10 patients,consisting of four with head and neck cancers,four with gastrointestinal cancers,one with lung cancer,and one with uterine cancer,were included. f-miso pet/ct was performed twice,before rt and during fractionated rt of approximately 20 gy/10 fractions,for eight of the 10 patients. f-miso maximum standardized uptake values (suvmax) of normal muscles and tumors were measured. the tumor-to-muscle (t/m) ratios of f-miso suvmax were also calculated. mean suvmax ± standard deviation (sd) of normal muscles was 1.25 ± 0.17,and suvmax above the mean + 2 sd (=1.60 suv) was regarded as a hypoxic area. nine of the 10 tumors had an f-miso suvmax of =1.60. all eight tumors examined twice showed a decrease in the suvmax,t/m ratio,or percentage of hypoxic volume (f-miso =1.60) at approximately 20 gy,indicating reoxygenation. in conclusion,accumulation of f-miso of =1.60 suv was regarded as an intratumoral hypoxic area in our f-miso pet/ct system. most human tumors (90%) in this small series had hypoxic areas before rt,although hypoxic volume was minimal (0.0-0.3%) for four of the 10 tumors. in addition,reoxygenation was observed in most tumors at two weeks of fractionated rt. © the author 2013. published by oxford university press on behalf of the japan radiation research society and japanese society for therapeutic radiology and oncology.