Magnetic resonance imaging (MRI) data were collected from 4 imaging centers located in Cheadle, Reading, Newcastle, and Bristol. Information about image acquisition and processing is available at the UK Biobank website in the brain scan protocol and brain imaging documentation (35 (link),36 ). Briefly, participants were scanned with a Siemens Skyra 3T scanner with a standard Siemens 32-channel head coil. T1-weighted imaging (resolution: 1.0 × 1.0 × 1.0 mm; field-of-view: 208 × 256 × 256 matrix) and T2 FLAIR imaging (resolution: 1.05 × 1.0 × 1.0 mm; field-of-view: 192 × 256 × 256 matrix) were performed to provide volumes of brain tissues and structures. Summary measures of brain structure were generated by an image-processing pipeline developed and run on behalf of the UK Biobank, using publicly available image-processing tools (the FMRIB Software Library, version 5.0.10 and FreeSurfer, version 6.0) (37 (link)).
In this study, the volumes (in cubic millimeters) of total brain, gray matter, white matter, hippocampus, and WMH were assessed. Extreme outlying data points (further than ±4 standard deviations [SD] from the mean) were excluded (0.002% of the total imaging-derived phenotype data analyzed). All MRI parameters were converted to z-scores, and WMH volume was log-transformed due to its skewed distribution.
In this study, the volumes (in cubic millimeters) of total brain, gray matter, white matter, hippocampus, and WMH were assessed. Extreme outlying data points (further than ±4 standard deviations [SD] from the mean) were excluded (0.002% of the total imaging-derived phenotype data analyzed). All MRI parameters were converted to z-scores, and WMH volume was log-transformed due to its skewed distribution.
Free full text: Click here
