MR Diffusion-weighted imaging(DWI) of Malignant Melanoma in Head and Neck after Accelerated Carbon-Ion Radiotherapy

PURPOSE: To report change of diffusion weighted imaging(DWI) of malignant melanoma in head and neck after carbon-ion radiotherapy. MATERIAL and METHOD: Eighteen patients having malignant melanoma in head and neck regions undertook carbon-ion radiotherapy at the National Institute of Radiological Sciences, Chiba, Japan. We examined using DWIBS (diffusion-weighted imaging with background body signal suppression) method before and after the treatment. ADC (apparent diffusion coefficient) value was measurable in nine of 18 cases (mean age:65yrs,age range:56-78,5 males and 4 females). We compared the ADC value before the treatment with the after one. Intera Achieva 1.5T Nova Dual system (Philips Medical) was used for the examination. The EPI-based diffusion-weighted imaging sequence with SPIR fat suppression was applied at the settings of two b-values, namely 0 and 1000 sec/mm^2, respectively. Results: Average ADC value for all clinical cases were 0.897x10^-3 (S.D.: 0.142x10^-3) at pre-treatment and 1.355x10^-3 (S.D.: 0.573x10^-3) at post-treatment. ADC values were increased in eight of 9 cases and decreased in one. There was a significant difference in ADC value between pre- and post-treatment (P