Cerebral MRI in a prospective cohort study on depression and atherosclerosis: the BiDirect sample, processing pipelines, and analysis tools

Abstract

Background: The use of cerebral magnetic resonance imaging (MRI) in observational studies has increased exponentially in recent years, making it critical to provide details about the study sample, image processing, and extracted imaging markers to validate and replicate study results. This article reviews the cerebral MRI dataset from the now-completed BiDirect cohort study, as an update and extension of the feasibility report published after the first two examination time points.

Methods: We report the sample and flow of participants spanning four study sessions and twelve years. In addition, we provide details on the acquisition protocol; the processing pipelines, including standardization and quality control methods; and the analytical tools used and markers available.

Results: All data were collected from 2010 to 2021 at a single site in Münster, Germany, starting with a population of 2,257 participants at baseline in 3 different cohorts: a population-based cohort (n = 911 at baseline, 672 with MRI data), patients diagnosed with depression (n = 999, 736 with MRI data), and patients with manifest cardiovascular disease (n = 347, 52 with MRI data). During the study period, a total of 4,315 MRI sessions were performed, and over 535 participants underwent MRI at all 4 time points.

Conclusions: Images were converted to Brain Imaging Data Structure (a standard for organizing and describing neuroimaging data) and analyzed using common tools, such as CAT12, FSL, Freesurfer, and BIANCA to extract imaging biomarkers. The BiDirect study comprises a thoroughly phenotyped study population with structural and functional MRI data.

Relevance statement: The BiDirect Study includes a population-based sample and two patient-based samples whose MRI data can help answer numerous neuropsychiatric and cardiovascular research questions.

Key points: • The BiDirect study included characterized patient- and population-based cohorts with MRI data. • Data were standardized to Brain Imaging Data Structure and processed with commonly available software. • MRI data and markers are available upon request.

Keywords: Longitudinal studies; Magnetic resonance imaging; Medical image processing; Population health; Standardization.

Fig. 1

MRI sequences recorded during the four examination sessions. The different protocols are arranged from top to bottom, while the sessions are represented by four columns. The plus cohort was carried out only in sessions 4 and 6 within subcohorts from the population and depression cohorts

Fig. 2

Distribution of age-stratified by session on the x-axis, cohort on the horizontal subplots, and available data on the vertical subplots (“all”—all BiDirect participants; “with MRI”—subset of BiDirect participants with MRI data; “with MRI Plus”—subset of BiDirect participants with MRI plus protocol data. Shown are boxplots with the median at each session and dotplots with a bin width of 0.5 years on the left. The color intensity of the distributions shows a confidence interval from 66 to 95%

Fig. 3

Bar chart of available MRI data stratified by session on the x-axis and cohort by horizontal subplot. The bars show the proportion of available or missing data per cohort and session from Table 1 on the y-axis. The numbers show the numbers of observations from each category. The data availability coloring of the bars shows loss to follow-up (orange), study participation without acquisition of MRI data (blue), and available MRI data (current session, light green; all four sessions, green)

Fig. 4

Alluvial plot of available data stratified by session on the x-axis and cohort by horizontal subplot. The bars (strata) show the proportion of available or missing data per cohort and session from Table 1 on the y-axis. The numbers in the strata show the observations in each category. The alluvia are lines that extend from s0 to s6 and contain the number of observations that fall into each category. The data availability coloring of the bars shows loss to follow-up (orange), study participation without acquisition of MRI data (blue), and available MRI data (green)

Fig. 5

Neuroimaging pipelines: input sequence types, frameworks, and functions used