Determining object boundaries from MR images with sub-pixel resolution: Towards in-line inspection with a mobile tomograph

Danieli, Ernesto; Berdel, Klaus; Perlo, Juan; Michaeli, Walter; Masberg, U.; Blümich, Bernhard; Casanova, Federico

doi:10.1016/j.jmr.2010.08.004

Cited by 19 publications

(10 citation statements)

References 11 publications

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“…It consists of multiple stacked rings of permanent magnets of a SmCo alloy arranged in a Halbach array so that the magnetic field B 0 of 0.57 T (24.2 MHz for the hydrogen atom) points perpendicular to the main axis of the magnet (Fig. 1a) (Danieli et al, 2010). Adjustable shim magnets are placed between the fixed building blocks and, together with the gradient system, homogeneity of <6 ppm for a working volume of 40 by 40 by 40 mm is achievable.…”

Section: Methodsmentioning

confidence: 99%

Combination of Magnetic Resonance Imaging and Neutron Computed Tomography for Three‐Dimensional Rhizosphere Imaging

Haber‐Pohlmeier

Tötzke

Lehmann

et al. 2019

Vadose Zone Journal

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Core Ideas 3D MRI relaxation time maps reflect water mobility in root, rhizosphere, and soil. 3D NCT water content maps of the same plant complement relaxation time maps. The relaxation time T1 decreases from soil to root, whereas water content increases. Parameters together indicate modification of rhizosphere pore space by gel phase. The zone of reduced T1 corresponds to the zone remaining dry after rewetting. In situ investigations of the rhizosphere require high‐resolution imaging techniques, which allow a look into the optically opaque soil compartment. We present the novel combination of magnetic resonance imaging (MRI) and neutron computed tomography (NCT) to achieve synergistic information such as water mobility in terms of three‐dimensional (3D) relaxation time maps and total water content maps. Besides a stationary MRI scanner for relaxation time mapping, we used a transportable MRI system on site in the NCT facility to capture rhizosphere properties before desiccation and after subsequent rewetting. First, we addressed two questions using water‐filled test capillaries between 0.1 and 5 mm: which root diameters can still be detected by both methods, and to what extent are defined interfaces blurred by these imaging techniques? Going to real root system architecture, we demonstrated the sensitivity of the transportable MRI device by co‐registration with NCT and additional validation using X‐ray computed tomography. Under saturated conditions, we observed for the rhizosphere in situ a zone with shorter T1 relaxation time across a distance of about 1 mm that was not caused by reduced water content, as proven by successive NCT measurements. We conclude that the effective pore size in the pore network had changed, induced by a gel phase. After rewetting, NCT images showed a dry zone persisting while the MRI intensity inside the root increased considerably, indicating water uptake from the surrounding bulk soil through the still hydrophobic rhizosphere. Overall, combining NCT and MRI allows a more detailed analysis of the rhizosphere's functioning.

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Section: Methodsmentioning

confidence: 99%

Combination of Magnetic Resonance Imaging and Neutron Computed Tomography for Three‐Dimensional Rhizosphere Imaging

Haber‐Pohlmeier

Tötzke

Lehmann

et al. 2019

Vadose Zone Journal

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“…Tabletop MRI instruments are mostly used to investigate the origin, proliferation and cure of disease on mice . They are also employed to study harvest quality, and their use as process‐control sensors is being tested to image the complex shape of rubber profiles during the extrusion process . Furthermore, they find applications in the analysis of transport, mixing, and separation phenomena in chemical engineering and process control .…”

Section: Fourier Nmrmentioning

confidence: 99%

Desktop NMR and Its Applications From Materials Science To Organic Chemistry

2017

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NMR spectroscopy is an indispensable method of analysis in chemistry, which until recently suffered from high demands for space, high costs for acquisition and maintenance, and operational complexity. This has changed with the introduction of compact NMR spectrometers suitable for small-molecule analysis on the chemical workbench. These spectrometers contain permanent magnets giving rise to proton NMR frequencies between 40 and 80 MHz. The enabling technology is to make small permanent magnets with homogeneous fields. Tabletop instruments with inhomogeneous fields have been in use for over 40 years for characterizing food and hydrogen-containing materials by relaxation and diffusion measurements. Related NMR instruments measure these parameters in the stray field outside the magnet. They are used to inspect the borehole walls of oil wells and to test objects nondestructively. The state-of-the-art of NMR spectroscopy, imaging and relaxometry with compact instruments is reviewed.

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“…Kleine MRT‐Geräte werden meist zur Untersuchung der Entstehung, Ausbreitung und Heilung von Krankheiten bei Mäusen eingesetzt . Sie werden auch zur Kontrolle der Erntequalität eingesetzt, und ihre Verwendung als Sensoren für komplexe Formen von Gummiprofilen zur Kontrolle des Extrusionsprozesses wird getestet . Darüber hinaus finden sie Anwendung für die Analyse von Transport‐, Misch‐ und Trennphänomenen in der chemischen Verfahrenstechnik und Prozesskontrolle .…”

Section: Fourier‐nmrunclassified

NMR mit Tischgeräten und deren Anwendungen von der Materialwissenschaft bis zur organischen Chemie

Blümich

Singh

2017

Angewandte Chemie

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Die NMR‐Spektroskopie ist eine unverzichtbare Analysemethode. Bis vor kurzem erforderten die Geräte viel Platz, waren teuer und schwer zu bedienen. Dies hat sich mit der Einführung kompakter NMR‐Spektrometer geändert, die sich für die Analyse kleiner Moleküle auf der Laborbank eignen. Solche Spektrometer sind mit Permanentmagneten für 1H‐NMR‐Frequenzen zwischen 40 und 80 MHz ausgestattet. Erst seit wenigen Jahren gibt es kleine Permanentmagnete mit homogenen Magnetfeldern für hochaufgelöste Spektroskopie. Tischgeräte mit inhomogenen Feldern werden schon seit 40 Jahren zur Charakterisierung von Lebensmitteln und Materialien über Relaxations‐ und Diffusionsmessungen genutzt. Ähnliche NMR‐Geräte messen diese Parameter im Streufeld außerhalb des Magneten. Sie werden zur Untersuchung von Bohrlochwänden in Ölquellen sowie für zerstörungsfreie Analysenverwendet. Der gegenwärtige Stand von NMR‐Spektroskopie, ‐Bildgebung und ‐Relaxometrie wird hier anhand repräsentativer Beispiele beschrieben.

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Determining object boundaries from MR images with sub-pixel resolution: Towards in-line inspection with a mobile tomograph

Cited by 19 publications

References 11 publications

Combination of Magnetic Resonance Imaging and Neutron Computed Tomography for Three‐Dimensional Rhizosphere Imaging

Combination of Magnetic Resonance Imaging and Neutron Computed Tomography for Three‐Dimensional Rhizosphere Imaging

Desktop NMR and Its Applications From Materials Science To Organic Chemistry

NMR mit Tischgeräten und deren Anwendungen von der Materialwissenschaft bis zur organischen Chemie

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