Chu-Yu Lee1, Leland Hu2, Leslie C. Baxter3, Josef P. Debbins3
1Electrical Engineering, Arizona State University, Tempe, AZ, United States; 2Department of Radiology, Mayo Clinic Arizona, Phoenix, AZ, United States; 3Neuroimaging Research, Barrow Neurological Institute, Phoenix, AZ, United States
Resolving the regions of recurrent tumor from post-treatment radiation effects (PTRE) can be challenging, because both can appear enhancing on the contrast enhanced T1 imaging, as shown in Fig. 1a and 1e. Diffusion-weighted Imaging (DWI) was shown to correlate with tumor cellularity . Recently, DWI with a higher b-value was found to have greater sensitivity to the changes in tumor cellularity [2, 3]. While the complications of treatment-bed changes involve tumor growth, radiation- and operation-induced lesions [4, 5], the intra-voxel diffusion heterogeneity measured by the high b-value DWI may be useful in differentiating between pathological mechanisms. In this study, two multiple b-value diffusion models: the stretched exponential model (α-DWI)  and diffusion kurtosis imaging (DKI)  were used to assess the recurrent tumor and the PTRE. Their fitted parameters: α and Kapp quantify the diffusion heterogeneity without information about the number of water compartments.