Neuroimaging

High-completeness brain imaging in SIGNAL enabled precise stroke subtyping and cerebrovascular phenotyping. The combination of imaging, cerebrospinal fluid markers, and clinical data supports head-to-head testing of biomarkers across dementia subtypes. SIGNAL's high MRI capture rate is a primary advantage enabling detailed small vessel disease phenotyping compared with prior UK registries. SIGNAL's MRI protocol included T1-weighted, T2-weighted, FLAIR, DWI, and SWI sequences, with a subset receiving diffusion tensor imaging. Relying on electronic health records to define cardiovascular risk factors introduces a risk of misclassification or detection bias in the registry. The neuroimaging protocol enabled detection and characterisation of features supporting phenotyping of cerebral small vessel disease.