Dose-related microstructural changes in metastatic patients measured with diffusion MRI: First insights of the APRICOT trial

Abstract

ABSTRACT:

Background: Radiotherapy (RT) is one of the most common therapeutic intervention for cerebral tumor, which also promotes changes in healthy brain structures, leading to cognitive decline in the majority of the patients. In this study, we aim to evaluate the changes in brain microstructure as a result of radiation delivery by means of diffusion MRI (dMRI). Methods: We selected 9 metastatic patients from the APRICOT trial who underwent both pre-RT and post-RT DWI and T1 scans. We estimated the diffusion metrics for a total of 31 white matter pathways and then evaluated their change as a function of the received dose (%/Gy). Results: The largest FA and AFD decreases were recorded in the Right Inferior Longitudinal Fasciculus, 7,84 %/Gy and the Left Uncinate Fasciculus, 61,09 %/Gy. Regarding the diffusivities, the Right Corticospinal Tract increased the most for all three metrics, MD, AD and RD 4,76 %/Gy, and 5,02 %/Gy and 7,47 %/Gy respectively. Conclusion: Diffusion metrics are susceptible to radiation delivery, AFD presenting the most notable changes. These findings imply the use of dMRI in better understanding the mechanisms behind structural changes, which may lead to cognitive decline.