Whole-brain radiotherapy associated with structural changes resembling aging as determined by anatomic surface-based...

Area of Science:

• Neuroscience
• Radiotherapy Research
• Medical Imaging Analysis

Background:

• Brain metastases are common intracranial tumors linked to high morbidity and mortality.
• Whole-brain radiotherapy (WBRT) is a palliative treatment but can cause neurocognitive deficits.
• Previous studies show localized hippocampal injury after WBRT, but global structural changes are less understood.

Purpose of the Study:

• To investigate global structural shape changes in the brain after WBRT.
• To quantify the accelerated aging effect of WBRT on the brain and its substructures.
• To compare the effects of conventional WBRT versus hippocampal avoidance (HA)-WBRT on brain structure.

Main Methods:

• Utilized MRI brain anatomic surface data from healthy controls and patients with brain metastases.
• Implemented a graph convolutional neural network to estimate "brain age" from structural data.
• Employed a mixed-effects linear model to compare brain age before and after WBRT.

Main Results:

• Analyzed 4220 subjects (4148 controls, 72 patients).
• Found accelerated brain aging post-WBRT: whole brain (9.32x), cortex (8.05x), subcortical structures (12.57x), and hippocampus (10.14x).
• Hippocampus aged 8.88x faster after conventional WBRT compared to HA-WBRT.

Conclusions:

• WBRT induces structural brain changes resembling rapid aging, up to 13 times the normal pace.
• Hippocampal avoidance offers protection to the hippocampus structure against WBRT-induced aging.
• Future research should correlate these structural changes with neurocognitive outcomes.