ABSTRACT NUMBER: ESOC2026A2159 DYNAMIC CHANGES IN APPARENT DIFFUSION COEFFICIENT SURROUNDING CEREBRAL MICROINFARCTS IN CANCER PATIENTS: A LONGITUDINAL MRI STUDY

Abstract Background and aims Acute incidental cerebral microinfarcts (CMIs) are small cortical/subcortical ischemic lesions that appear as diffusion-restricted-foci on MRI-DWI and are detectable only briefly after onset. While uncommon in the general population, CMIs are more frequent in patients with cerebrovascular disease and cancer. The temporal evolution of apparent diffusion coefficient(ADC) values in CMIs remains incompletely understood Methods We performed a retrospective cohort study. Patients with lung, breast, pancreatic, or colorectal cancer underwent brain MRI with DWI before and/or after cancer diagnosis were included. CMIs were manually segmented as regions of interest(ROIs) and coregistered across baseline,acute,and follow-up scans. Homologous contralateral ROIs served as controls. ADC values were analyzed using mixed-effects linear models with timepoint and ROI as factors, followed by post-hoc paired t-tests Results Twenty-eight CMIs from 17 patients (mean-age 64 years) were analyzed, most with lung cancer. A significant interaction between timepoint and ROI was observed(p<0.001). No ADC difference was detected at baseline. At the acute CMI timepoint, ADC values were significantly reduced in lesions compared with controls, whereas at follow-up ADC values were significantly increased. This biphasic pattern was consistent across cancer types and tissue classes. Conclusions CMIs show a biphasic ADC trajectory with acute reduction followed by subsequent elevation, paralleling the diffusion behavior of larger ischemic infarcts. This likely reflects cytotoxic edema followed by tissue disintegration or gliosis. ADC dynamics appear to be a robust marker of microinfarct evolution and may have potential value for cerebrovascular risk stratification in oncology populations. Conflict of interest nothing to disclose"