MRI and Computational Modelling of Current Flow for taVNS Dataset
We performed a high-resolution T1 and T2 weighted magnetization prepared gradient echo (MPRAGE) MRI scans at the Advanced Science Research Center (ASRC), The Graduate Center, City University of New York (CUNY), using a 3-T Siemens Prisma scanner (Siemens Healthineers, Germany). Ear scan was acquired using ZOOMit technology for high-resolution zoomed FOV imaging allowing high contrast and less artifact for region of interest with 0.47 voxel size. Based on optimized high-resolution (0.47 mm) T1 and T2 weighted images from a single healthy adult female (age: 30) subject, we developed an anatomical model of the left ear and the surrounding head tissues including brain/grey-matter, CSF/meninges skull, muscle, blood vessels, fat, cartilage, and skin, included here as RAW files, we developed an anatomical model of the left ear and the surrounding head tissues including brain, CSF/meninges, skull, muscle, blood vessels, fat, cartilage, and skin. Six regions of interest (ROIs): cavum concha, cymba concha, crus of helix, tragus, antitragus, and earlobe were also segmented and are all within the folder 'Segmentation Masks Raw Files'. A range of taVNS electrode montages were reproduced spanning varied electrodes sizes and placements over the tragus, cymba concha, earlobe, cavum concha, and crus of helix. Electric field across the ear (for both skin and cartilage) for each montage at 1 mA or 2 mA taVNS, assuming an activation threshold of 6.15 V/m, 12.3 V/m or 24.6 V/m, was predicted using a Finite element method (FEM). These are also included here in 'STL and MPHTXT Files of Montage FE Models'. Relative targeting was robust across assumptions of activation threshold and tissue properties. Computational models provide additional insight on how details in electrode shape and placement impact sensitivity, current density distribution, selectivity, and location, thereby supporting analysis of existing approaches and optimization of new devices. Our result suggest taVNS current patterns and relative target are robust across individuals, through (variance in) axon morphology were not represented. Also included here is the full Simpleware ScanIP (Synopsys, CA, USA) file containing all of the FE models and tissue masks. RAW files of the tissue masks and STL and MPHTXT files are included within their respective folders. All files are labeled for their MRI sequence description, what tissue is contained within the mask, and what montage is within the STL or MPHTXT respectively in their folders.
Steps to reproduce
After exporting every FE model from ScanIP or using the corresponding STL or MPHTXT files given here, the file can be imported into current flow simulating software of choice such as COMSOL, Abaqus, Mimics, etc.