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*) and after (R2) CCRT and the ΔR2 (ΔR2=R2 - R2) 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 between RG and NRG (P = 0.307); however, there were significant differences in R2 and ΔR2 (P < 0.001). The area under the curve of R2 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.