Diffusion Kurtosis as an in vivo Imaging Marker of Early Radiation-Induced Changes in Radiation-Induced Temporal Lobe Necrosis in Nasopharyngeal Carcinoma Patients.

PURPOSE

Diffusion kurtosis imaging (DKI), an extension of the popular diffusion tensor imaging (DTI) model, has been applied in clinical studies of brain tissue changes. We explored the value of DKI for the early detection of radiation-induced changes in temporal lobe necrosis (TLN) after radiotherapy (RT) for nasopharyngeal carcinoma (NPC).

METHODS

A total of 400 patients with NPC were retrospectively enrolled; all participants underwent MRI scans 0-7 days before RT, at 4 weeks during RT, and 1 month after completing RT. DKI-derived kurtosis parameters (mean kurtosis [MK], axial kurtosis [K], radial kurtosis [K]), and DKI-derived diffusion parameters (fractional anisotropy [FA], mean diffusivity [MD], axial diffusivity [λ], radial diffusivity [λ]) were assessed in temporal lobe white matter.

RESULTS

Analysis was performed for 20 patients with temporal lobe necrosis following long-term follow-up. No brain abnormalities were visible on conventional MRI in any patient at 4 weeks during RT and 1 month after RT. Of all DKI-derived parameters, MK was significantly lower at 1 month after RT than before RT (P < 0.05).

CONCLUSION

This study indicates DKI can detect the early presence of relatively subtle RT-induced brain abnormalities before TLN in patients with NPC and may provide a sensitive imaging technique for temporal white matter microstructural abnormalities that are silent on conventional modalities but precede TLN after RT.