# MASiVar: Multisite, Multiscanner, and Multisubject Acquisitions for Studying Variability in Diffusion Weighted Magnetic Resonance Imaging ## Authors and Reference [Leon Y. Cai](mailto:leon.y.cai@vanderbilt.edu), Qi Yang, Praitayini Kanakaraj, Vishwesh Nath, Allen T. Newton, Heidi A. Edmonson, Jeffrey Luci, Benjamin N. Conrad, Gavin R. Price, Colin B. Hansen, Cailey I. Kerley, Karthik Ramadass, Fang-Cheng Yeh, Hakmook Kang, Eleftherios Garyfallidis, Maxime Descoteaux, Francois Rheault, Kurt G. Schilling, and Bennett A. Landman. MASiVar: Multisite, Multiscanner, and Multisubject Acquisitions for Studying Variability in Diffusion Weighted Magnetic Resonance Imaging. bioRxiv, 2020. Preprint. [Medical-image Analysis and Statistical Interpretation (MASI) Lab](https://my.vanderbilt.edu/masi), Vanderbilt University, Nashville, TN, USA ## Overview MASiVar is a dataset designed to promote investigation of diffusion MRI variability consisting of 319 diffusion scans acquired at 3T from b = 1000 to 3000 s/mm2 across 97 different healthy subjects and four different scanners at three different sites. Cohort I consists of one subject scanned repeatedly on one scanner. This subject underwent three separate imaging sessions and acquired 3-4 scans per session. Cohort II consists of 5 subjects each scanned on 3-4 different scanners across 3 institutions. Each subject underwent 1-2 sessions on each scanner and had one scan acquired per session. Cohort III consists of 91 subjects all scanned on one scanner. Each subject underwent 1-5 sessions on the scanner and had two scans acquired per session. The acquisitions acquired per scan are as follows: | Cohort | Shell (b-value) | Number of Directions| |--------|-----------------|---------------------| | I | 1000 | 96 | | | 1500 | 96 | | | 2000 | 96 | | | 2500 | 96 | | | 3000 | 96 | | II | 1000 | 30 to 33 | | | 1000 | 96 | | | 1500 | 96 | | | 2000 | 96 | | | 2465 or 2500 | 96 | | III | 1000 | 40 | | | 2000 | 56 | ## Naming Scheme MASiVar is in BIDS format with the following naming scheme: * Subject: __sub-c__\__s__\ * For cohort III, subjects with prefix A are adults and those with prefix C are children. * Session: __ses-s__\__x__\ * Acquisition: __acq-b__\__n__\__r__\__pe__\ * Shells are indicated by b-value (s/mm2) * Resolutions are presented in 10-1 mm to maintain BIDS compliance. * Phase encoding direction APP indicates posterior-to-anterior and APA indicates anterior-to-posterior. * Run: __run-__ Example: `sub-cIs1_ses-s1Ax2_acq-b3000n96r25x25x25peAPP_run-105_dwi.nii.gz` is the fifth acquisition in the first scan of session 2 at site 1A for subject 1 of cohort I acquired with 96 directions at b = 3000 s/mm2 and a resolution of 2.5mm isotropic in the posterior-to-anterior phase encoding direction. Note: Most of the sessions in MASiVar are named sequentially, however, some are not due to missed or truncated imaging sessions. ## Derivatives Both raw and preprocessed MASiVar data are available de-faced and de-identified. Diffusion images were preprocessed with PreQual v1.0.0 under default settings. More information about PreQual can be found here: https://github.com/MASILab/PreQual. In short, all acquisitions per scan were denoised with the Marchenko-Pastur technique, intensity normalized such that the average b = 0 s/mm2 intensity distributions within the brain maximally intersected, and distortion corrected. Distortion correction included susceptibility-induced distortion correction using APA b = 0 s/mm2 volumes when available and the Synb0-DisCo deep learning framework when not, eddy current-induced distortion correction, intervolume motion correction, and slice-wise signal drop out imputation. ## Changelog * v1.0.0: Initial Release