Microvascular and microstructural brain abnormalities in paediatric haematological cancer survivors are related to cognitive deficits: An <scp>IVIM</scp> ‐ <scp>FWI MRI</scp> study

Microvascular, inflammatory and myelin pathologies may contribute to chemotherapy-related cognitive impairment (CRCI). This study applied a novel three-compartment intravoxel incoherent motion-free water imaging (IVIM-FWI) technique that estimates the perfusion fraction (PF), free water fraction (FW) and anisotropic diffusion of tissue (FAt) to study microvascular and microstructural changes in grey and white matter regions in 16 cancer survivor (CS) participants compared to 15 matched healthy controls (HCs). We found significantly decreased PF and increased FW in grey and white matter regions and significantly decreased FAt in white matter regions in the CS versus HC group. These changes were located in key regions involved in emotion, cognition and sensory processing. Furthermore, in both groups, decreased FAt and varying changes in PF and FW were significantly associated with poor performance on cognitive tests assessing general cognitive ability, fluid intelligence, inhibition and processing speed. Overall, the three-compartment IVIM-FWI model provides neuroinflammation, myelination and microvascular metrics that may be related to CRCI pathologies and are associated with cognition. This approach may facilitate targeted interventions aimed at preserving cognitive function and improving overall quality of life for paediatric haematological cancer survivors.