Objective To explore the clinical value of follow-up MRI before and after chemoradiotherapy for patients with non-surgical laryngeal or hypopharyngeal carcinoma. Methods Twenty five patients with non-surgical laryngeal or hypopharyngeal squamous cell carcinoma were analyzed. These patients had pathologically confirmed disease and underwent routine contrast-enhanced MRI examination before chemoradiotherapy and at 3，6，9，and 12 months afterwards. Change in the largest area of the primary lesion was monitored， and edema status was assessed using the signal-to-noise ratio（SNR） and contrast-to-noise ratio （CNR） of non-tumor tissue on T2-weighted images. Diffusion-weighted imaging（DWI） were obtained for 10 patients，and the apparent diffusion coefficient（ADC） parameter was monitored in this subgroup. Results In all patients，the largest area of the primary lesion decreased significantly during follow-up（P<0.05），and the primary lesion could not be detected in 17 patients by 3 months after chemoradiotherapy，in another 4 patients by 6 months afterwards， and in another 4 patients by 9 months afterwards. SNR of non-tumor tissue was similar before chemoradiotherapy and at 3 months afterwards，and it was significantly higher than pre-therapy at all other time points. CNR of non-tumor tissue was significantly higher at all post-therapy time points than before therapy（P＜0.05）. ADC in the subgroup of 10 patients was significantly higher after therapy（P＜0.05）. Conclusion MRI can clearly detect changes in the primary lesion of laryngeal and hypopharyngeal carcinoma. Most lesions were undetectable within 3 months after therapy. Monitoring SNR and CNR may help evaluate changes in non-tumor tissue edema， and monitoring the ADC parameter may help assess treatment response.
