Ein Überblick zur digitalen Bildverarbeitung in der Lebensmittelwissenschaft 1. Mitt. Bestimmung geometrischer Merkmale an isolierten Objekten

I. Fromhold-Treu und W. Kozerke: A survey on digital picture processing in food science. Part 1. Determination of geometrical properties of isolated objects The aim of this series of articles is a summary of procedures and methods of the digital picture processing with the point of view of their special application in the science of nutrition and food. After a short introduction to the fundamentals of the digital picture processing some effective procedures of the recognition of isolated objects in binary pictures are given. Furthermore there are defined geometrical properties for these objects.     

Ramping down a clinical 3 T scanner: a journey into MRI and MRS at 0.75 T

Object

Lower-field MR is reemerging as a viable, potentially cost-effective alternative to high-field MR, thanks to advances in hardware, sequence design, and reconstruction over the past decades. Evaluation of lower field strengths, however, is limited by the availability of lower-field systems on the market and their considerable procurement costs. In this work, we demonstrate a low-cost, temporary alternative to purchasing a dedicated lower-field MR system.

Materials and Methods

By ramping down an existing clinical 3 T MRI system to 0.75 T, proton signals can be acquired using repurposed ¹³C transmit/receive hardware and the multi-nuclei spectrometer interface. We describe the ramp-down procedure and necessary software and hardware changes to the system.

Results

Apart from presenting system characterization results, we show in vivo examples of cardiac cine imaging, abdominal two- and three-point Dixon-type water/fat separation, water/fat-separated MR Fingerprinting, and point-resolved spectroscopy. In addition, the ramp-down approach allows unique comparisons of, e.g., gradient fidelity of the same MR system operated at different field strengths using the same receive chain, gradient coils, and amplifiers.

Discussion

Ramping down an existing MR system may be seen as a viable alternative for lower-field MR research in groups that already own multi-nuclei hardware and can also serve as a testing platform for custom-made multi-nuclei transmit/receive coils.

     

Cardiac- versus diaphragm-based respiratory navigation for proton spectroscopy of the heart

Magnetic Resonance Materials in Physics, Biology and Medicine - To study inter-individual differences of the relation between diaphragm and heart motion, the objective of the present study was to...     

Ein Überblick zur digitalen Bildverarbeitung in der Lebensmittelwissenschaft 2. Mitt. Rekonstruktion von Konturen isolierter Objekte

The boundaries of objects in digital binary pictures can be disturbed by several sources, so that it is impossible to detect the whole objects. In such cases methods for the reconstruction of the objects are needed. The approximation of objects by ellipsis, spline-functions and surrounding convex polygons are treated. Also a reconstruction of objects by dilatation and erosion is possible. Finally a method proposed by Toussaint and Donaldson is discribed.     

Ein Überblick zur digitalen Bildverarbeitung in der Lebensmittelwissenschaft 4. Mitt. Merkmalsbestimmung in Grauwertbildern

A survey on digital picture processing in food science. Part 4. Determination of properties in gray-reale pictures The efficient algorithms for the recognition of objects in binary pictures can easily transmitted to gray-scale pictures, if a decision rule is known, which is suitable to differentiate between the pixels of objects and background. For this three methods are discussed. Furthermore properties of objects are defined, which result from the gray value of the objects.     

Automatic accurate non-invasive quantitation of blood flow, cross-sectional vessel area, and wall shear stress by modelling of magnetic resonance velocity data

OBJECTIVES: To apply a new, automatic and non-invasive method for quantification of blood flow, dynamic cross-sectional vessel area, and wall shear stress (WSS) by in vivo magnetic resonance velocity mapping of normal subjects. DESIGN: Prospective, open study. MATERIALS: Six young volunteers. METHODS: A three-dimensional paraboloid model enabling automatic determination of blood flow, vessel distensibility and WSS was applied to blood velocity determinations in the common carotid artery. Blood flow was also determined by a manual edge detection method. RESULTS: Using the new method, the common carotid mean blood flow was 7.28 (5.61-9.63) (mean (range)) ml/s. By the manual-method blood flow was 7.21 (5.55-9.60) ml/s. Mean luminal vessel area was 26% larger in peak systole than in diastole. Mean/peak WSS was 0.82/2.28 N/m2. Manually and automatically determined flows correlated (r2 = 0.998, p < 0.0001). WSS and peak centre velocity were associated (r2 = 0.805, p < 0.0001). CONCLUSIONS: Blood flow, luminal vessel area dilatation, and WSS can be determined by the automatic three-dimensional paraboloid method. The hypothesis of association between peak centre velocity and WSS was not contradicted by the results of the present study.