Dose-dependent degeneration of non-cancerous brain tissue in post-radiotherapy patients: A diffusion tensor imaging study

Abstract

Background and purpose: Radiation-induced changes in brain tissue may relate to post-radiotherapy (RT) cognitive decline. Our aim is to investigate changes of the brain microstructural properties after exposure to radiation during clinical protocols of RT using diffusion MRI (dMRI). Methods and Materials: The susceptibility of tissue changes to radiation was investigated in a clinically heterogenic cohort (age, pathology, tumor location, type of surgery) consisting of 121 scans of 18 patients (10 females). The imaging dataset included 18 planning CTs and 103 dMRI scans (range 2-14, median = 6 per patient) assessing pre-operative, post-operative pre-RT and post-RT states. Diffusion tensor imaging (DTI) metrics were estimated from all scans for a region-of-interest based linear relation analysis between mean dose and change in DTI metrics, while partial volume effects were regressed out. Results: The largest regional dose dependency with mean diffusivity appear in the white matter of the frontal pole in the left hemisphere by an increase of 2.61 %/(Gy x year). Full brain-wise, pooled results for white matter show fractional anisotropy to decrease by 0.85 %/(30Gy x year); mean diffusivity increase by 9.17 %/(30Gy x year); axial diffusivity increase by 7.30%/(30Gy x year) and radial diffusivity increases by 10.63%/(30Gy x year). Conclusions: White matter is susceptible to radiation with some regional variability where diffusivity metrics demonstrate the largest relative sensitivity. This suggests that dMRI is a promising tool in assessing microstructural changes after RT, which can help in understanding treatment-induced cognitive decline.

Dose-dependent volume loss in subcortical deep grey matter structures after cranial radiotherapy

“…Thinning rates are found to be dose-dependent, meaning that a higher dose leads to a further diminished cortex. Similarly, diffusion tensor imaging has shown that white matter shows dose-dependent changes in several metrics after RT [7] . Finally, two grey matter structures, the hippocampus [8] , [9] and the amygdala [10] , show susceptibility to radiation damage, again with higher volume changes with increasing dose.…”

Dose-dependent volume loss in subcortical deep grey matter structures after cranial radiotherapy

“…Thinning rates are found to be dosedependent, meaning that a higher dose leads to a further diminished cortex. Similarly, diffusion tensor imaging has shown that white matter shows dose-dependent changes in several metrics after RT [7].…”

Morphological changes after cranial fractionated photon radiotherapy: localized loss of white matter and grey matter volume with increasing dose

“…Tail approximation was used for faster calculations (27). Significant DBM changes were expressed as relative volume changes per received radiation dose (%/Gy), while significant VBM changes are expressed in mm 3 is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint…”

“…MR images were acquired on the same 3T scanner (Philips Ingenia, Philips Medical Systems, Best, The Netherlands) as part of routine clinical care. T1-weighted MR images were acquired with a 3D spoiled gradient (TFE) sequence without gadolinium enhancement with the following parameters: TR = 8.1 ms, TE = 3.7 ms, flip angle = 8°, 213 axial slices, matrix: 207 x 289, voxel resolution 0.96 × 0.96 x 1.00 mm 3 . The planning CT scans were acquired on a Brilliance Big bore scanner (Philips Medical Systems, Best, The Netherlands), with a tube potential of 120 kVp, with use of a matrix size of 512 × 512 and 0.65 × 0.65 × 3.0 mm 3 voxel size.…”

“…Advances in imaging techniques have allowed the examination of the precise morphological changes in the brain after RT. Changes of white matter (WM) (3), cerebral cortex (4–7), and subcortical grey matter (GM) structures (8–10) have already been linked to received dose in several studies. However, these investigations have focused on specific parts or structures of the brain, which may limit the generalizability of the acquired knowledge.…”