1,721,053 research outputs found
Correlation of cerebral magnetic resonance elastography with cognitive performance in patients with multiple sclerosis
No full textCorrelation of cerebral magnetic resonance elastography with cognitive performance in patients with multiple sclerosis
No full textMR Elastography (MRE) for the Differentiation of Intracranial Tumors - Results of a Histology Correlated Study
No full textMR Elastography (MRE) for the Differentiation of Intracranial Tumors - Results of a Histology Correlated Study
No full textQuantification of Biophysical Parameters in Medical Imaging
No full textThis book provides a selection of essential knowledge on the image-based quantification of biophysical parameters for the purpose of clinical diagnosis. The authors regard clinical imaging scanners as physical measurement systems capable of quantifying intrinsic parameters for depiction of the constitution and biophysical properties of in vivo tissue. On the one hand, this approach supports the development of new methods of imaging highly reproducible, system-independent, and quantitative biomarkers, and these methods receive detailed attention in the book. On the other hand, the reader will also gain a deeper understanding of how physical tissue properties interact with the generation of signals in medical imaging, opening new windows on the intricate and fascinating relationship between the structure and function of living tissues. The book will be of interest to all who recognize the limitations of basing clinical diagnosis primarily on visual inspection of images and who wish tolearn more about the diagnostic potential of quantitative and biophysics-based medical imaging markers and the challenges that the paucity of such markers poses for next-generation imaging technologies
Quantification of Biophysical Parameters in Medical Imaging
No full textThe second edition of this book offers six new chapters covering the latest developments in quantitative medical imaging, including artificial intelligence, MRI mapping, sonography, elastography and cardiac CT. All the other existing chapters have been updated and expanded, many with new text and figures, to reflect the rapid translation and advancement of technology in this exciting area of biomedical research. This updated edition presents fundamental knowledge on the imaging quantification of biophysical parameters for clinical diagnostic purposes. Clinical imaging scanners are considered by the authors as physical measurement systems capable of quantifying intrinsic parameters for the representation of the constitution and biophysical properties of tissues in vivo. In one respect, this approach fosters the development of new imaging methods for highly reproducible, system-independent, and quantitative biomarkers. These methods are greatly detailed in the book. Alternatively, this new edition equips the reader with a better understanding of how the physical properties of tissues interact with signal generation in medical imaging, opening up new insights into the complex and fascinating relationship between structure and function in living tissues. This updated edition is of interest to all those who recognize the limitations of clinical diagnosis based primarily on visual inspection of images, and who wish to learn more about the diagnostic potential of quantitative, biophysically-based medical imaging markers, as well as the challenges posed by the scarcity of such markers for next-generation imaging technologies
Erweiterung der fMRI durch Hyperscanning und Neurofeedback : Entwicklung und Anwendung
Get PDFDie Möglichkeiten, neuronale Aktivität während sozialer Interaktionen zu untersuchen, werden durch
echtzeitbasierte funktionelle Bildgebung (rt-fMRI) in Verbindung mit virtueller Realität (VR) erheblich er-
weitert. In dieser Arbeit wurde ein rt-fMRI Softwarepaket durch die Integration von Neurofeedback (NFB)-
Modulen erweitert und für den Einsatz in der Neurobildgebung validiert. Zur Untersuchung verschiedener
Aspekte und zur Validierung der neu entwickelten Methoden und Softwareanwendungen wurden vier
Pilotstudien durchgeführt. Eine zentrale Herausforderung bestand in der Kopplung eines Hochfeld- (3T)
mit einem Ultrahochfeld-MRT (7T), einer Technik, die als Hyperscanning bekannt ist und weltweit nur an
wenigen Standorten zur Verfügung steht. Eine Innovation dieser Arbeit besteht darin, dass die Interaktion
der Probanden in einer VR, die sowohl kooperativ als auch kompetitiv gesteuert werden kann, in Echtzeit
analysiert wird. Zusätzlich ermöglichte die Signalkalibrierung den direkten Vergleich verschiedener Mag-
netfeldstärken. Weitere Einflussfaktoren wie Emotionen und Aufmerksamkeit wurden ebenfalls unter-
sucht. In den NFB-Studien zeigte sich, dass Feedback über abstrakte, konventionelle Amplitudenanzeigen
als effektiver wahrgenommen wurde als über die Modifikation des emotionalen Ausdrucks computerge-
nerierter Gesichter. Es konnten Hirnareale identifiziert werden, die mit verschiedenen Emotionen in Re-
aktion auf interne und externe Stimuli assoziiert sind, wobei diese Areale individuelle Unterschiede auf-
weisen. Das Potenzial dieser Methoden geht über individuelles NFB hinaus und reicht bis zur direkten
Wahrnehmung der Gehirnaktivität eines Interaktionspartners in Echtzeit. Die entwickelte Infrastruktur
kann als erweiterte Gehirn-Computer-Schnittstelle genutzt werden. Durch den Einsatz fortgeschrittener
Echtzeit-Signalanalysemethoden und die Erhöhung der Anzahl der Probanden können die individuellen
Ergebnisse optimiert und die Gruppenanalyse verbessert werden
The influence of physiological aging and atrophy on brain viscoelastic properties in humans.
Get PDFPhysiological aging of the brain is accompanied by ubiquitous degeneration of neurons and oligodendrocytes. An alteration of the cellular matrix of an organ impacts its macroscopic viscoelastic properties which can be detected by magnetic resonance elastography (MRE)--to date the only method for measuring brain mechanical parameters without intervention. However, the wave patterns detected by MRE are affected by atrophic changes in brain geometry occurring in an individual's life span. Moreover, regional variability in MRE-detected age effects is expected corresponding to the regional variation in atrophy. Therefore, the sensitivity of brain MRE to brain volume and aging was investigated in 66 healthy volunteers aged 18-72. A linear decline in whole-brain elasticity was observed (-0.75%/year, R-square = 0.59, p<0.001); the rate is three times that determined by volume measurements (-0.23%/year, R-square = 0.4, p<0.001). The highest decline in elasticity (-0.92%/year, R-square = 0.43, p<0.001) was observed in a region of interest placed in the frontal lobe with minimal age-related shrinkage (-0.1%, R-square = 0.06, p = 0.043). Our results suggest that cerebral MRE can measure geometry-independent viscoelastic parameters related to intrinsic tissue structure and altered by age
Vibration-synchronized magnetic resonance imaging for the detection of myocardial elasticity changes
No full textVibration synchronized magnetic resonance imaging of harmonically oscillating tissue interfaces is proposed for cardiac magnetic resonance elastography. The new approach exploits cardiac triggered cine imaging synchronized with extrinsic harmonic stimulation (f = 22.83 Hz) to display oscillatory tissue deformations in magnitude images. Oscillations are analyzed by intensity threshold-based image processing to track wave amplitude variations over the cardiac cycle. In agreement to literature data, results in 10 volunteers showed that endocardial wave amplitudes during systole (0.13 ± 0.07 mm) were significantly lower than during diastole (0.34 ± 0.14 mm, P < 0.001). Wave amplitudes were found to decrease 117 ± 40 ms before myocardial contraction and to increase 75 ± 31 ms before myocardial relaxation. Vibration synchronized magnetic resonance imaging improves the temporal resolution of magnetic resonance elastography as it overcomes the use of extra motion encoding gradients, is less sensitive to susceptibility artifacts, and does not suffer from dynamic range constraints frequently encountered in phase-based magnetic resonance elastography
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