Feasibility of diffusion weighted MR imaging in differentiating recurrent laryngeal carcinoma from radionecrosis

To assess the feasibility of apparent diffusion coefficient (ADC) generated from diffusion weighted magnetic resonance imaging as a non invasive technique to differentiate tumor recurrence from radionecrosis in patients with laryngeal carcinoma. Twenty one patients suspected of tumor recurrence underwent MRI including diffusion weighted imaging (DWI) (b 0 and 1000). ADC maps were generated and ADC values were measured at the lesion sites and the normal laryngeal tissues, and were compared with the histopathological results. The mean ADC of tumor recurrence {1.04 ± 0.34 × 10−3 mm2/s (SD)} was significantly lower (p < 0.0001) than the mean ADC of the normal laryngeal tissues in the same patient (1.48 ± 0.099 × 10−3 mm2/s) while the mean ADC of radionecrosis (1.79 ± 0.41 × 10−3 mm2/s) was significantly higher (p < 0.04) than the mean ADC of the normal laryngeal tissues (1.49 ± 0.095 × 10−3 mm2). The mean ADC of tumor recurrence is significantly lower (p < 0.0001) than the mean ADC of radionecrosis with 1.16 × 10−3 mm2/s is the best cut value for differentiating tumor recurrence from radionecrosis. ADC can differentiate tumor recurrence from radionecrosis in laryngeal carcinoma.