Automated deep learning segmentation of high-resolution 7 T postmortem MRI for quantitative analysis of structure-pathology correlations in neurodegenerative diseases

Postmortem MRI allows brain anatomy to be examined at high resolution and to link pathology measures with morphometric measurements. However, automated segmentation methods for brain mapping in postmortem MRI are not well developed, primarily due to limited availability of labeled datasets, and heterogeneity in scanner hardware and acquisition protocols. In this work, we present a high resolution of 135 postmortem human brain tissue specimens imaged at 0.3 mm$^{3}$ isotropic using a T2w sequence on a 7T whole-body MRI scanner. We developed a deep learning pipeline to segment the cortical mantle by benchmarking the performance of nine deep neural architectures, followed by post-hoc topological correction. We then segment four subcortical structures (caudate, putamen, globus pallidus, and thalamus), white matter hyperintensities, and the normal appearing white matter. We show generalizing capabilities across whole brain hemispheres in different specimens, and also on unseen images acquired at 0.28 mm^3 and 0.16 mm^3 isotropic T2*w FLASH sequence at 7T. We then compute localized cortical thickness and volumetric measurements across key regions, and link them with semi-quantitative neuropathological ratings. Our code, Jupyter notebooks, and the containerized executables are publicly available at: https://pulkit-khandelwal.github.io/exvivo-brain-upennComment: Preprint submitted to NeuroImage Project website: https://pulkit-khandelwal.github.io/exvivo-brain-upen

Microelectronics, nanoelectronics:step behind the red brick wall using the thermal domain

Abstract The More-than-Moore Grand Challenge is a hot topic of present day solid state electronics: one way to step behind the “red brick wall” is the 3D heterogeneous integration of different systems with the conventional (standard) CMOS-technology. The aim of this study is to summarize the different bit representation methods, especially possibilities of our new, patented phonsistor (phonon transistor) based thermal-electronic logic system or thermal-electronic logic circuit (TELC). TELC is the first logic gate approach using two different physical quantities, i.e. electrical and thermal for bit representation within one system

Neuromorphic thermal-electric circuits based on phase-change VO2 thin-film memristor elements

Abstract The basis of the powerful operation of the brain is the variability of neuron operation, i.e., it can be digital or analog, and the logic operation of a neuron-based system can be parallel and series. The challenge is to set up an artificial intelligent architecture that mimics neuro-biological architectures present in the nervous system. Our proposed new active device (phonon transistor = phonsistor) and thermal electric logic circuit (TELC) seem to be appropriate devices for neuron modeling. Key elements of the phonsistor and TELC are memristors realized by VO2 phase change output resistors integrated with dissipating elements as inputs. These components are coupled to each other by thermal and/or electrical effects. On short distances, the information can be carried by heat diffusion and on longer distances by electrical signals. This is a similarity with human neurons where the information is carried by diffusing neurotransmitter molecules on short distances and electrically by the axons on longer distances. For example, very new ideas are presented of neuromorphic circuits for mimicking the biological neuron synapse operation and the action potential generation. Further similarities with biological neural systems are the auto-oscillation phenomenon with chaotic properties, the ability of integrating subthreshold excitations within the thermal time constant, and the memory effect of the memristive components. The TELC should be compatible with CMOS technology, as the realization of both systems utilizes conventional thin-film technology steps at similar temperature ranges. The physical appearance and construction of the TELC gate are also similar to the neuron

Real time magnetic resonance guided endomyocardial local delivery

Objective: To investigate the feasibility of targeting various areas of left ventricle myocardium under real time magnetic resonance (MR) imaging with a customised injection catheter equipped with a miniaturised coil. Design: A needle injection catheter with a mounted resonant solenoid circuit (coil) at its tip was designed and constructed. A 1.5 T MR scanner with customised real time sequence combined with in-room scan running capabilities was used. With this system, various myocardial areas within the left ventricle were targeted and injected with a gadolinium-diethylenetriaminepentaacetic acid (DTPA) and Indian ink mixture. Results: Real time sequencing at 10 frames/s allowed clear visualisation of the moving catheter and its transit through the aorta into the ventricle, as well as targeting of all ventricle wall segments without further image enhancement techniques. All injections were visualised by real time MR imaging and verified by gross pathology. Conclusion: The tracking device allowed real time in vivo visualisation of catheters in the aorta and left ventricle as well as precise targeting of myocardial areas. The use of this real time catheter tracking may enable precise and adequate delivery of agents for tissue regeneration

Real time magnetic resonance guided endomyocardial local delivery

Objective: To investigate the feasibility of targeting various areas of left ventricle myocardium under real time magnetic resonance (MR) imaging with a customised injection catheter equipped with a miniaturised coil. Design: A needle injection catheter with a mounted resonant solenoid circuit (coil) at its tip was designed and constructed. A 1.5 T MR scanner with customised real time sequence combined with in-room scan running capabilities was used. With this system, various myocardial areas within the left ventricle were targeted and injected with a gadolinium-diethylenetriaminepentaacetic acid (DTPA) and Indian ink mixture. Results: Real time sequencing at 10 frames/s allowed clear visualisation of the moving catheter and its transit through the aorta into the ventricle, as well as targeting of all ventricle wall segments without further image enhancement techniques. All injections were visualised by real time MR imaging and verified by gross pathology. Conclusion: The tracking device allowed real time in vivo visualisation of catheters in the aorta and left ventricle as well as precise targeting of myocardial areas. The use of this real time catheter tracking may enable precise and adequate delivery of agents for tissue regeneration

Lipid lowering by simvastatin induces regression of human atherosclerotic lesions: two years' follow-up by high-resolution noninvasive magnetic resonance imaging

BackgroundStatins are widely used to treat hypercholesterolemia and atherosclerotic disease. Noninvasive MRI allows serial monitoring of atherosclerotic plaque size changes. Our aim was to investigate the effects of lipid lowering with simvastatin on atherosclerotic lesions.Methods and resultsA total of 44 aortic and 32 carotid artery plaques were detected in 21 asymptomatic hypercholesterolemic patients at baseline. The effects of statin on these atherosclerotic lesions were evaluated as changes versus baseline in lumen area (LA), vessel wall thickness (VWT), and vessel wall area (VWA) by MRI. Maximal reduction of plasma total and LDL cholesterol by simvastatin (23% and 38% respectively; PConclusionThe present study demonstrates that maintained lipid-lowering therapy with simvastatin is associated with significant regression of established atherosclerotic lesions in humans. Our observations indicate that lipid-lowering therapy is associated with sustained vascular remodeling and emphasize the need for longer-term treatment.Roberto Corti, Valentin Fuster, Zahi A. Fayad, Stephen G. Worthley, Gerard Helft, Donald Smith, Jesse Weinberger, Jolanda Wentzel, Gabor Mizsei, Michele Mercuri, and Juan J. Badimo