Can the apparent transverse relaxation rate (R2(*)) evaluate the efficacy of concurrent chemoradiotherapy in locally advanced nasopharyngeal carcinoma? a preliminary experience

BACKGROUND: The use of the apparent transverse relaxation rate (R2(*)) in nasopharyngeal carcinoma (NPC) has not been previously reported in the literature. The aim of this study was to investigate the role of the R2(*) value in evaluating response to concurrent chemoradiotherapy (CCRT) in patients with NPC. METHODS: Forty-one patients with locoregionally advanced NPC confirmed by pathology were examined by blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) before and after CCRT, and conventional MRI was performed 3 months after the completion of CCRT. All patients were divided into a responding group (RG) and a nonresponding group (NRG), according to MRI findings 3 months after the end of treatment. The R2(*) values before (R2*(preT)) and after (R2(*)(postT)) CCRT and the ΔR2(*) (ΔR2(*)=R2(*)(postT) – R2(*)(preT)) were calculated in the tumor. RESULTS: Among the 41 patients, 26 were in the RG and 15 were in the NRG. There was no statistical difference in the R2(*)(preT) between RG and NRG (P = 0.307); however, there were significant differences in R2(*)(postT) and ΔR2(*) (P < 0.001). The area under the curve of R2(*)(postT) and ΔR2(*) for predicting the therapeutic response of NPC was 0.897 and 0.954, respectively, with cutoff values of 40.95 and 5.50 Hz, respectively. CONCLUSION: The R2(*) value can be used as a potential imaging indicator to evaluate the therapeutic response of locoregionally advanced NPC.