To predict the radiosensitivity of nasopharyngeal carcinoma using intravoxel incoherent motion MRI at 3.0 T.

Purpose: To investigate intravoxel incoherent motion (IVIM) MRI for evaluating the sensitivity of radiotherapy on nasopharyngeal carcinoma (NPC).

Results: The reproducibility between intra-observer and inter-observer was relatively good. (0.72×10 mm/s±0.14 . 0.54×10 mm/s±0.23; < 0.001) and * (157.92×10 mm/s±15.21 . 120.36×10 mm/s±10.22; < 0.0001) were significantly higher in effective group than poor-effective group, whereas the difference of (18.79%±2.51 . 16.47%±1.51) and (1.21×10 mm/s±0.11 . 1.33×10 mm/s±0.23) could not reach statistical significant between the 2 groups ( > 0.05).

Conclusions: IVIM may be potentially useful in assessing the radiosensitivity of NPC. The higher value combining with higher * value might indicate the more radiosensitive of NPC, and increased * might reflect increased blood vessel generation and parenchymal perfusion in NPC.

Materials And Methods: Sixty consecutive patients (20 female, range, 27-83 years, mean age, 52 years) newly diagnosed NPC in the stage of T3 or T4 were enrolled. Forty-two of them were divided into effective group clinically after a standard radiotherapy according to the RECIST criteria. IVIM with 13 b-values (range, 0-800 s/mm) and general MRI were performed at 3.0T MR scanner before and after radiotherapy. The parameters of IVIM including perfusion fraction (), perfusion-related diffusion (*), pure molecular diffusion () and apparent diffusion coefficient () were calculated. Two radiologists major in MRI diagnose analyzed all images independently and placed regions of interest (ROIs). Intra-class correlation coefficient (ICC) was used to evaluate intra-observer and inter-observer agreement. And Mann-Whitney test was used to assess the differences between the two groups.