MESA Exam 6 Brain MRI

The Multi-Ethnic Study of Atherosclerosis (MESA) is a US community cohort of 6,814 adults aged 45 to 84 at enrolment in 2000 to 2002, free of known cardiovascular disease at the time. During its sixth exam, an ancillary study on atrial fibrillation combined ambulatory heart rhythm monitoring with a research brain MRI. This entry covers that brain MRI collection. It is not a downloadable dataset: outside researchers submit a proposal to the MESA Coordinating Center, need a senior MESA author as sponsor, and sign a Data and Materials Distribution Agreement for the approved project.

Composition

1,062 participants completed brain MRI in 2018 and 2019, 32 of them without the cardiac monitoring. After excluding scans with large structural lesions, failed quality control or missing images, 1,036 had complete measures. In that group the mean age was 72 years (SD 8), 549 were women, and participants identified as Black (259), Chinese-American (155), Hispanic (199) or White (423).

Acquisition

Scans were done at six MESA field centres on 3 T Siemens Prisma and Skyra systems with a common protocol supervised by the University of Pennsylvania Brain MRI Reading Center. Sequences include 1 mm isotropic 3D T1w, T2w and FLAIR, 2D diffusion tensor imaging, 3D pseudo-continuous ASL, 3D multi-echo gradient echo for SWI and quantitative susceptibility mapping, and resting-state and breath-hold fMRI.

Annotations

The protocol paper reports derived brain, grey and white matter volumes, white matter hyperintensity volume and fractional anisotropy. The DEEPMIR study (Rashid et al. 2021) manually segmented cerebral microbleeds and non-haemorrhagic basal ganglia iron deposits on SWI, QSM and T2w in a convenience sample of 24 participants, chosen for suspected microbleeds, and published code but not the labels. No source says these labels are distributed. The DMDA forbids recipients to pass on data or derivatives and asks them to return Resultant Data to MESA, so the subset is not a separate entry.

Known limitations

• Which image files the Coordinating Center releases for an approved project is not published.
• The two papers describe the scanners differently: DEEPMIR names two Skyra and four Prisma Fit systems at six sites, the protocol paper names Prisma at five centres and Skyra at two.
• Sex and age are reported only for the 1,036 participants with complete measures.
• The sample is not a clinical cohort, so microbleeds and other lesions are sparse.