The goal of capturing imaging phenotypes relevant to the widest possible range of diseases and hypotheses meant that the protocol must deliver data with the broadest predictive power for neuropathology and mental health. We therefore included modalities that drive estimates of anatomical and neuropathological structure (“structural MRI”), brain activity (“functional MRI”, or fMRI), and local tissue microstructure (“diffusion MRI”, dMRI). The resulting imaging protocol (Supplementary Table 1) included: three structural modalities, T1-weighted, T2-weighted and susceptibility-weighted MRI (referred to here as T1, T2 and swMRI); dMRI; and both task and resting-state functional MRI (tfMRI and rfMRI). Recent advances in MRI acquisition technology8 enabled high spatial resolution dMRI and fMRI with high angular and temporal resolution, respectively, despite strict time constraints. For example, the protocol acquires dMRI data with 100 diffusion-encoding directions over two shells in just 7 minutes, enabling advanced model fitting of microstructural parameters that would not have been possible under these time constraints with previous generation technology. Following optimization of acquisition protocols, streamlining of participant preparation and minimization of scanner dead time (see Online Methods), UK Biobank was able to incorporate six neuroimaging modalities in just 36 minutes.
