Value of magnetic resonance diffusion-weighted imaging for the prediction of radiosensitivity in nasopharyngeal carcinoma

Abstract

Objective: The effectiveness of radiotherapy in nasopharyngeal carcinoma (NPC) is closely related to the radiosensitivity of the carcinoma; however, there is currently no effective method to predict radiosensitivity in NPC. We explored the predictive value of magnetic resonance diffusion-weighted imaging (MR-DWI) for radiosensitivity in NPC. Study Design Prospective cohort study. Setting Single hospital.

Subjects and methods: Patients with NPC who received intensity-modulated radiotherapy (IMRT) with or without chemotherapy were enrolled from April 2010 through November 2011. Primary tumor apparent diffusion coefficient (ADC) was measured before treatment (ADC0) and 2 weeks after the start of IMRT (ADC1). ADC change (ΔADC) was calculated as (ADC1 - ADC0)/ADC0 * 100%. Three months after the end of radiotherapy, the short-term effect of radiotherapy was assessed using the World Health Organization's response evaluation criteria in solid tumors.

Results: Of 134 eligible NPC patients, 121 received combination chemotherapy. Three months after radiotherapy, residual local tumors were detected in 23 (17.2%) cases, and no residual tumors were detected in 111 (82.8%) cases. There was no significant difference in the residual tumor rates of patients receiving combination chemotherapy vs those who did not (P = 1.000). There were no significant differences in the ADC0 or ADC1 values of patients with and without residual tumors (P = .083 and .262). The ΔADC values of patients with (49.77% ± 31.02%) and without (68.35% ± 34.22%) residual tumors were significantly different (t = -2.406, P = .017). Logistic regression analysis indicated that ΔADC was an independent prognostic factor for the short-term effect of IMRT in NPC.

Conclusion: Magnetic resonance diffusion-weighted imaging may potentially have value for predicting radiosensitivity in NPC.

Keywords: apparent diffusion coefficient; diffusion-weighted imaging; nasopharyngeal carcinoma; radiosensitivity.