Dr. Leuze is working on techniques for visualization of MRI data using virtual and augmented reality devices. He has developed an MRI viewer for the Samsung Gear VR and has presented projects on MRI data volumetric visualization and registration to the real world using the Microsoft Hololens and the Intel RealSense camera. Dr. Leuze is furthermore refining MRI techniques for measuring brain circuits by validation with tissue clearing and optical imaging methods.
Honors & Awards
Stanford Neuroscience Insitute Interdisciplinary Scholar Awards, Stanford Neuroscience Insitute (2015)
Otto-Hahn-Medal, Max Planck Society (2014)
Education & Certifications
PhD, Max Planck Institute for Human Cognitive and Brain Sciences & University of Leipzig, Physics (2013)
MS, University of Leipzig, Physics (2008)
BrainVR (5/2016 - 10/2016)
VR app about the brain for the Samsung Gear VR
For More Information:
Ars Electronica (7/2013 - 9/2013)
Production of a 3D movie about the brain for the Ars Electronica 2013 in Linz/Austria
For More Information:
- Holographic Visualization of Brain MRI with Real-Time Alignment to a Human Subject 25th Annual meeting of the International Society for Magnetic Resonance in Medicine
- Marker-less co-registration of MRI data to a subject’s head via a mixed reality device 26th Annual meeting of the International Society for Magnetic Resonance in Medicine
The separate effects of lipids and proteins on brain MRI contrast revealed through tissue clearing.
Despite the widespread use of magnetic resonance imaging (MRI) of the brain, the relative contribution of different biological components (e.g. lipids and proteins) to structural MRI contrasts (e.g., T1, T2, T2*, proton density, diffusion) remains incompletely understood. This limitation can undermine the interpretation of clinical MRI and hinder the development of new contrast mechanisms. Here, we determine the respective contribution of lipids and proteins to MRI contrast by removing lipids and preserving proteins in mouse brains using CLARITY. We monitor the temporal dynamics of tissue clearance via NMR spectroscopy, protein assays and optical emission spectroscopy. MRI of cleared brain tissue showed: 1) minimal contrast on standard MRI sequences; 2) increased relaxation times; and 3) diffusion rates close to free water. We conclude that lipids, present in myelin and membranes, are a dominant source of MRI contrast in brain tissue.
View details for DOI 10.1016/j.neuroimage.2017.04.021
View details for PubMedID 28411157
Early Non-invasive Detection of Acute 1,2-Dichloroethane-induced Toxic Encephalopathy in Rats.
2016; 30 (6): 787-793
To assess the acute effect of 1,2-dichloroethane (1,2-DCE) on rat brain using diffusion magnetic resonance imaging (dMRI).We performed dMRI on 30 male Sprague-Dawley rats, microstructural alterations were investigated by calculating the mean fractional anisotropy (FA) and apparent diffusion coefficient (ADC) changes in eight selected brain regions of interest. For the whole brain, clusters of 20+ voxels that differed significantly in FA and ADC between groups were marked. Hematoxylin-eosin staining was performed to confirm pathological changes.Brain images showed lesions with brain edema in the white matter in both hemispheres in all groups exposed to 1,2-DCE. Diffusivity values were significantly different after 1,2-DCE inhalation (p<0.05).Primarily cytotoxic edema occurred in acute 1,2-DCE-induced brain edema in rats. dMRI could be used for the early non-invasive detection of acute 1,2-DCE-induced toxic encephalopathy.
View details for PubMedID 27815462
Layer-Specific Intracortical Connectivity Revealed with Diffusion MRI
2014; 24 (2): 328-339
In this work, we show for the first time that the tangential diffusion component is orientationally coherent at the human cortical surface. Using diffusion magnetic resonance imaging (dMRI), we have succeeded in tracking intracortical fiber pathways running tangentially within the cortex. In contrast with histological methods, which reveal little regarding 3-dimensional organization in the human brain, dMRI delivers additional understanding of the layer dependence of the fiber orientation. A postmortem brain block was measured at very high angular and spatial resolution. The dMRI data had adequate resolution to allow analysis of the fiber orientation within 4 notional cortical laminae. We distinguished a lamina at the cortical surface where diffusion was tangential along the surface, a lamina below the surface where diffusion was mainly radial, an internal lamina covering the Stria of Gennari, where both strong radial and tangential diffusion could be observed, and a deep lamina near the white matter, which also showed mainly radial diffusion with a few tangential compartments. The measurement of the organization of the tangential diffusion component revealed a strong orientational coherence at the cortical surface.
View details for DOI 10.1093/cercor/bhs311
View details for Web of Science ID 000329840900005
View details for PubMedID 23099298
Myelin and iron concentration in the human brain: A quantitative study of MRI contrast.
During the last five years ultra-high-field magnetic resonance imaging (MRI) has enabled an unprecedented view of living human brain. Brain tissue contrast in most MRI sequences is known to reflect mainly the spatial distributions of myelin and iron. These distributions have been shown to overlap significantly in many brain regions, especially in the cortex. It is of increasing interest to distinguish and identify cortical areas by their appearance in MRI, which has been shown to be feasible in vivo. Parcellation can benefit greatly from quantification of the independent contributions of iron and myelin to MRI contrast. Recent studies using susceptibility mapping claim to allow such a separation of the effects of myelin and iron in MRI. We show, using post-mortem human brain tissue, that this goal can be achieved. After MRI scanning of the block with appropriate T1 mapping and T2* weighted sequences, we section the block and apply a novel technique, proton induced X-ray emission (PIXE), to spatially map iron, phosphorus and sulfur elemental concentrations, simultaneously with 1μm spatial resolution. Because most brain phosphorus is located in myelin phospholipids, a calibration step utilizing element maps of sulfur enables semi-quantitative ex vivo mapping of myelin concentration. Combining results for iron and myelin concentration in a linear model, we have accurately modeled MRI tissue contrasts. Conversely, iron and myelin concentrations can now be estimated from appropriate MRI measurements in post-mortem brain samples.
View details for DOI 10.1016/j.neuroimage.2014.02.026
View details for PubMedID 24607447
Systematic changes to the apparent diffusion tensor of in vivo rat brain measured with an oscillating-gradient spin-echo sequence
2013; 70: 10-20
As the oscillating gradient spin-echo sequence has shown promise as a means to probe tissue microstructure, it was applied here to diffusion-tensor imaging of in vivo rat brain. The apparent diffusion tensor (ADT) was estimated for motion-probing gradient (MPG) frequencies in the range 33.3-133.3 Hz, and regions-of-interest (ROIs) in the corpus callosum (CC), visual cortex (VC), cerebellar white matter (CBWM) and cerebellar grey matter (CBGM) were selected for detailed analysis. There were substantial, approximately linear changes to the ADT with increasing MPG frequency for all four ROIs. All ROIs showed clear increases in mean diffusivity. CBWM had a substantial decrease in fractional anisotropy, whereas the CC and VC had minor increases of the same parameter. All eigenvalues of the ADT tended to increase with frequency for the CBWM, CBGM and VC, but only the principal eigenvalue increased strongly for the CC. On the other hand, there was no evidence that the orientation of the principal eigenvector varied systematically with MPG frequency for any of the ROIs. The relationship between the behaviour of the eigenvalues and the behaviours of the mean diffusivity and fractional anisotropy is investigated in detail. Pixelwise linear fits to the MD from individual animals found elevated changes across the cerebellum. The data acquired for this work encompassed a range of effective diffusion-times from 7.5 ms down to 1.875 ms, and some ideas on how the results might be used to extract quantitative information about brain tissue microstructure are discussed.
View details for DOI 10.1016/j.neuroimage.2012.12.036
View details for Web of Science ID 000315703800002
View details for PubMedID 23274188
Quantitative measurement of changes in calcium channel activity in vivo utilizing dynamic manganese-enhanced MRI (dMEMRI)
2012; 60 (1): 392-399
The ability of manganese ions (Mn(2+)) to enter cells through calcium ion (Ca(2+)) channels has been used for depolarization dependent brain functional imaging with manganese-enhanced MRI (MEMRI). The purpose of this study was to quantify changes to Mn(2+) uptake in rat brain using a dynamic manganese-enhanced MRI (dMEMRI) scanning protocol with the Patlak and Logan graphical analysis methods. The graphical analysis was based on a three-compartment model describing the tissue and plasma concentration of Mn. Mn(2+) uptake was characterized by the total distribution volume of manganese (Mn) inside tissue (V(T)) and the unidirectional influx constant of Mn(2+) from plasma to tissue (K(i)). The measurements were performed on the anterior (APit) and posterior (PPit) parts of the pituitary gland, a region with an incomplete blood brain barrier. Modulation of Ca(2+) channel activity was performed by administration of the stimulant glutamate and the inhibitor verapamil. It was found that the APit and PPit showed different Mn(2+) uptake characteristics. While the influx of Mn(2+) into the PPit was reversible, Mn(2+) was found to be irreversibly trapped in the APit during the course of the experiment. In the PPit, an increase of Mn(2+) uptake led to an increase in V(T) (from 2.8±0.3 ml/cm(3) to 4.6±1.2 ml/cm(3)) while a decrease of Mn(2+) uptake corresponded to a decrease in V(T) (from 2.8±0.3 ml/cm(3) to 1.4±0.3 ml/cm(3)). In the APit, an increase of Mn(2+) uptake led to an increase in K(i) (from 0.034±0.009 min(-1) to 0.049±0.012 min(-1)) while a decrease of Mn(2+) uptake corresponded to a decrease in K(i) (from 0.034±0.009 min(-1) to 0.019±0.003 min(-1)). This work demonstrates that graphical analysis applied to dMEMRI data can quantitatively measure changes to Mn(2+) uptake following modulation of neural activity.
View details for DOI 10.1016/j.neuroimage.2011.12.030
View details for Web of Science ID 000301218700040
View details for PubMedID 22227885