Correlation study between DKI and conventional DWI in brain and head and neck tumors.

PURPOSE: To investigate the relationship between the Diffusion Kurtosis Imaging (DKI) parameters and conventional metrics provided by Diffusion-weighted imaging (DWI) in patients affected by Brain or Head and Neck (HN) cancer.

METHODS: Ten patients affected by brain tumor and nine patients with HN tumor underwent a pre-treatment MR examination at 3 T. The largest tumor section was manually contoured by two expert neuroradiologists. The apparent diffusion coefficient (Dapp ) and apparent diffusional kurtosis (Kapp ) parameters were determined at the voxel level by using the DKI model, and compared to the apparent diffusion coefficient (ADC) and the tissue diffusion coefficient (Dmono ) obtained from mono-exponential fitting methods. The Akaike Information Criteria (AIC) was calculated to assess the quality of the fitting methods. Cross-correlations between all the variables were assessed using the Spearman rank test.

RESULTS: Increased Kapp values were found in each lesion. All parameters were strongly related, in particular an inverse relationship emerged between median values of Kapp and Dapp /Dmono /ADC in both patient groups, while Dapp showed positive correlations with Dmono and ADC. From the analysis at the voxel level, significant inverse associations were found between Kapp and Dmono within the lesions, while a weak or moderate association emerged between Kapp and ADC or Dapp .

CONCLUSIONS: A significant association between the apparent diffusional kurtosis Kapp and the tissue diffusion coefficient Dmono emerged for both brain and HN tumors at 3 T, suggesting that both variables may consistently reflect deeper insight into the microstructural characteristics of tumors.