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Background: As the usage of MRI for biomedical research increases, an ongoing goal for extending the usefulness of MRIs has been the increase of the magnet's field strength to 3T, 7T, and beyond. The 7T field strength has recently been given FDA‐approval for clinical use, due to recognition of its safety and ability to characterize "smaller structures and subtle pathologies" 1 when compared to 3T (Fig. 1.) Technological developments at the 7 Tesla Bioengineering Research Program (7TBRP) at University of Pittsburgh is currently enabling neuroimaging translational research for 35 active 7T‐based NIH research projects with projected ∼ 7000 7T scan sessions that focus on studying aging, AD, COVID‐19 among several other neurodegenerative diseases. Methods: We have developed a new (Fig. 2 and 3) device (Version 2 of Tic Tac Toe radiofrequency (RF) coil system) composed of 60 transmit channels – first of a kind ‐ and 32 receive channels. The coil has been deployed to Pittsburgh's Imaging Community and is currently being used in a wide variety of NIH‐funded studies. Results: Compared to other commercially available coils, this new RF coil system provides more homogeneous excitation, signal/contrast to noise ratio, and extended coverage of hard‐to‐reach regions at 7T (brain stem/temporal lobes/cerebellum.) Furthermore, the new RF coil system is also an anti‐claustrophobia solution at 7T as it provides a face opening in the front of the head resulting in more comfortable breathing, less claustrophobia, and a better overall 7T MRI experience for the participants. Conclusion: Among several other neurodegenerative diseases, advances in 7T MRI technology have allowed us to explore the common biology underlying aging, Alzheimer disease as well as the neurological sequelae following infection with SARS‐CoV‐2 (from imaging data harmonized across 3 different 7T sites) Funding: R56AG074467, R01MH111265 and R01AG063525 1. https://www.fda.gov/news-events/press-announcements/fda-clears-first-7t-magnetic-resonance-imaging-device [ABSTRACT FROM AUTHOR]

Background: White matter hyperintensities (WMHs) are neuroimaging features associated with Alzheimer's disease (AD). Ex‐vivo studies may enable better characterization of WMHs pathological substrates. In this work, we present a novel method that leverages in‐vivo and ex‐vivo MRIs and histopathology to analyze the progression of WMHs in AD. Method: A single subject's in‐vivo MRI scans at four different time points were analyzed. Ex‐vivo scans of the brain left hemisphere were done using 16‐Tx and 32‐Rx TicTacToe coil3 and a 3‐D printed enclosure with integrated cutting guides1 (Fig. 1). The WMHs were segmented on the T2‐weighted FLAIR in‐vivo MRI 2, and registered onto the final time point via SPM's normalized mutual information‐based algorithm. All four WMH segmentations were warped to the ex‐vivo MRI's space by applying the deformation field from the ITK in‐vivo to ex‐vivo registration. Result: The 3D printed enclosure achieved an accurate alignment between gross pathology, ex‐vivo and in‐vivo MRI (Fig. 1). Then, we computed the WMHs' growth over time warped onto the ex‐vivo MRI (Fig. 2). This growth was quantified as the total number of voxels in each segmentation longitudinally with a quadratic fit with an R2 =0.99 (Fig. 2). Lastly, we found a significant change in the distribution of WMH segmentations over time as evident by their normalized histograms (Fig. 3). Conclusion: We present a novel method to track the progression of WMHs in‐vivo to ex‐vivo MRI and gross pathology. Future studies will perform a voxel‐wise analysis on the WMHs in MRI scans, both in‐vivo and ex‐vivo, along with its histological correlates to gain insight into the underlying cellular mechanisms during the biomarker's development. References: 1. Nadim Farhat et al. "Reusable 3D printed enclosure with integrated cutting guides for the alignment of high resolution ex‐vivo MRI with ex‐vivo gross brain photographs." 2021 ISMRM Meeting (Under revision). 2. Wu, M. et al (2006). "A fully automated method for quantifying and localizing white matter hyperintensities on MR images." Psychiatry Research: Neuroimaging, 148(2‐3), 133‐142. 3. T. Santini et al., "In‐vivo and numerical analysis of the eigenmodes produced by a multi‐level Tic‐Tac‐Toe head transmit array for 7 Tesla MRI," PLoS One, vol. 13, no. 11, p. e0206127, Nov. 2018. [ABSTRACT FROM AUTHOR]