We are presenting a software tool developed for the purpose of atherosclerotic plaque study in hi... more We are presenting a software tool developed for the purpose of atherosclerotic plaque study in high resolution Magnetic Resonance Images. A new implementation of balloon-type active contour model used for segmentation and quantification of blood vessel lumen is described. Its originality resides in a dynamic scaling process which makes the influence of the balloon force independent of the current size of the contour. The contour can therefore be initialized by single point.
Introduction: High resolution diffusion-weighted imaging (DWI) and therefore fiber tractography i... more Introduction: High resolution diffusion-weighted imaging (DWI) and therefore fiber tractography is a challenge at ultra-high field strength. With higher field strength and resolution, susceptibility effects and T2* decay cause increased distortions, drop-outs and image degradation of single-shot EPI (ss-EPI) acquisitions. Parallel imaging can be used to improve the image quality of ss-EPI [1].
Abstract: bundles in the embedding tissue structures. White matter fiber tractography from diffus... more Abstract: bundles in the embedding tissue structures. White matter fiber tractography from diffusion tensor imaging (DTI) is, in general, visualized as 3D lines or tubes together with 2D anatomical MR slices or surfaces. However, determining the exact location of the fiber tracts in their surrounding anatomy is still unsolved. Rendering the embedding anatomy of fiber tracts provides new insight into the exact spatial arrangement of fiber bundles, their spatial relation, and tissue properties surrounding the tracts [SSA* 08].
Atherosclerosis is the most common cause of myocardial infarction. To study the atherosclerotic p... more Atherosclerosis is the most common cause of myocardial infarction. To study the atherosclerotic plaque in high resolution Magnetic Resonance images we developed a software tool called ATHER. An active contour model is used for segmentation and quantification of blood vessel lumen.
Methods: Experiments were performed on a 7 Tesla whole-body MR scanner (MAGNETOM 7T, Siemens Heal... more Methods: Experiments were performed on a 7 Tesla whole-body MR scanner (MAGNETOM 7T, Siemens Healthcare, Germany) with a 70 mT/m gradient coil. We used a 32-Channel head coil (Nova Medical, USA)(Luetzkendorf, 2010). All scans were performed on a healthy volunteer in a single session. An optimized Stesjkal Tanner sequence scheme (Morelli 2010) was used. Imaging parameters were kept the same except the resolution.
Method: We performed magnetic resonance and diffusion tensor imaging in a longitudinal design at ... more Method: We performed magnetic resonance and diffusion tensor imaging in a longitudinal design at four different time points before, during (after two and four weeks) and immediately after a six weeks period of motor skill learning in 14 adult human subjects. Learning consisted of only one weekly training session (45 minutes) in a complex dynamic balancing task (DBT). Stability of the acquired motor skill was assessed with a retention test three months after the end of the six weeks learning period.
Introduction. Diffusion MR imaging has made it possible to reveal the microgeometry of nervous ti... more Introduction. Diffusion MR imaging has made it possible to reveal the microgeometry of nervous tissue in vivo. The axonal mem4 branes of the nerve fibers, which are coherently oriented in the white matter of the brain and spinal cord, seem to form the major de4 terminant of anisotropic water diffusion [1]. The well4known diffusion tensor model [2] however proved inadequate for describing crossings and branchings of fiber tracts within a voxel.
A large body of evidence indicates that the hypothalamus is involved in pathogenetic mechanisms o... more A large body of evidence indicates that the hypothalamus is involved in pathogenetic mechanisms of mood disorders. It has been suggested that functional abnormalities of the hypothalamus are associated with structural hypothalamic changes. Structural neuroimaging allows in vivo investigation of the hypothalamus that may shed light on the underlying pathogenetic mechanisms of unipolar and bipolar disorder.
This paper presents a new approach for visual-based image retrieval method with respect to the MP... more This paper presents a new approach for visual-based image retrieval method with respect to the MPEG-7 still image description scheme. A segmentation method based on a multivariate minimum cross entropy is used hierarchically for partitioning the color image in classes and regions. Local and global descriptors are defined in order to characterize the color feature of these regions. The local descriptors provide information about the local activity in the image, and the global ones evaluate the qualitative image content.
Abstract To achieve a deeper understanding of language processing in the human brain, scientists ... more Abstract To achieve a deeper understanding of language processing in the human brain, scientists and clinicians use Electroencephalography (EEG) and Magnetoencephalography (MEG) inverse methods to reconstruct sources of Event Related Potentials. There exists a persistent uncertainty regarding the influence of volume conduction effects such as the anisotropy of tissue conductivity of the skull and the white matter layers on the inverse results.
Diffusion MR imaging has enabled the in vivo exploration of the connectional architecture in huma... more Diffusion MR imaging has enabled the in vivo exploration of the connectional architecture in human brain. This method particularly reveals the complex system of long-range nerve fibers that integrate the functionally distinct areas of the cerebral cortex. Since the fibers are not directly observed but the diffusion process of water molecules in the underlying material, a forward model is established that maps the microgeometry of nervous tissue onto the diffusion-weighted signals.
We are presenting a software tool developed for the purpose of atherosclerotic plaque study in hi... more We are presenting a software tool developed for the purpose of atherosclerotic plaque study in high resolution Magnetic Resonance Images. A new implementation of balloon-type active contour model used for segmentation and quantification of blood vessel lumen is described. Its originality resides in a dynamic scaling process which makes the influence of the balloon force independent of the current size of the contour. The contour can therefore be initialized by single point.
Introduction: High resolution diffusion-weighted imaging (DWI) and therefore fiber tractography i... more Introduction: High resolution diffusion-weighted imaging (DWI) and therefore fiber tractography is a challenge at ultra-high field strength. With higher field strength and resolution, susceptibility effects and T2* decay cause increased distortions, drop-outs and image degradation of single-shot EPI (ss-EPI) acquisitions. Parallel imaging can be used to improve the image quality of ss-EPI [1].
Abstract: bundles in the embedding tissue structures. White matter fiber tractography from diffus... more Abstract: bundles in the embedding tissue structures. White matter fiber tractography from diffusion tensor imaging (DTI) is, in general, visualized as 3D lines or tubes together with 2D anatomical MR slices or surfaces. However, determining the exact location of the fiber tracts in their surrounding anatomy is still unsolved. Rendering the embedding anatomy of fiber tracts provides new insight into the exact spatial arrangement of fiber bundles, their spatial relation, and tissue properties surrounding the tracts [SSA* 08].
Atherosclerosis is the most common cause of myocardial infarction. To study the atherosclerotic p... more Atherosclerosis is the most common cause of myocardial infarction. To study the atherosclerotic plaque in high resolution Magnetic Resonance images we developed a software tool called ATHER. An active contour model is used for segmentation and quantification of blood vessel lumen.
Methods: Experiments were performed on a 7 Tesla whole-body MR scanner (MAGNETOM 7T, Siemens Heal... more Methods: Experiments were performed on a 7 Tesla whole-body MR scanner (MAGNETOM 7T, Siemens Healthcare, Germany) with a 70 mT/m gradient coil. We used a 32-Channel head coil (Nova Medical, USA)(Luetzkendorf, 2010). All scans were performed on a healthy volunteer in a single session. An optimized Stesjkal Tanner sequence scheme (Morelli 2010) was used. Imaging parameters were kept the same except the resolution.
Method: We performed magnetic resonance and diffusion tensor imaging in a longitudinal design at ... more Method: We performed magnetic resonance and diffusion tensor imaging in a longitudinal design at four different time points before, during (after two and four weeks) and immediately after a six weeks period of motor skill learning in 14 adult human subjects. Learning consisted of only one weekly training session (45 minutes) in a complex dynamic balancing task (DBT). Stability of the acquired motor skill was assessed with a retention test three months after the end of the six weeks learning period.
Introduction. Diffusion MR imaging has made it possible to reveal the microgeometry of nervous ti... more Introduction. Diffusion MR imaging has made it possible to reveal the microgeometry of nervous tissue in vivo. The axonal mem4 branes of the nerve fibers, which are coherently oriented in the white matter of the brain and spinal cord, seem to form the major de4 terminant of anisotropic water diffusion [1]. The well4known diffusion tensor model [2] however proved inadequate for describing crossings and branchings of fiber tracts within a voxel.
A large body of evidence indicates that the hypothalamus is involved in pathogenetic mechanisms o... more A large body of evidence indicates that the hypothalamus is involved in pathogenetic mechanisms of mood disorders. It has been suggested that functional abnormalities of the hypothalamus are associated with structural hypothalamic changes. Structural neuroimaging allows in vivo investigation of the hypothalamus that may shed light on the underlying pathogenetic mechanisms of unipolar and bipolar disorder.
This paper presents a new approach for visual-based image retrieval method with respect to the MP... more This paper presents a new approach for visual-based image retrieval method with respect to the MPEG-7 still image description scheme. A segmentation method based on a multivariate minimum cross entropy is used hierarchically for partitioning the color image in classes and regions. Local and global descriptors are defined in order to characterize the color feature of these regions. The local descriptors provide information about the local activity in the image, and the global ones evaluate the qualitative image content.
Abstract To achieve a deeper understanding of language processing in the human brain, scientists ... more Abstract To achieve a deeper understanding of language processing in the human brain, scientists and clinicians use Electroencephalography (EEG) and Magnetoencephalography (MEG) inverse methods to reconstruct sources of Event Related Potentials. There exists a persistent uncertainty regarding the influence of volume conduction effects such as the anisotropy of tissue conductivity of the skull and the white matter layers on the inverse results.
Diffusion MR imaging has enabled the in vivo exploration of the connectional architecture in huma... more Diffusion MR imaging has enabled the in vivo exploration of the connectional architecture in human brain. This method particularly reveals the complex system of long-range nerve fibers that integrate the functionally distinct areas of the cerebral cortex. Since the fibers are not directly observed but the diffusion process of water molecules in the underlying material, a forward model is established that maps the microgeometry of nervous tissue onto the diffusion-weighted signals.
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Papers by Gabriele Lohmann