Search results for "aging"

Brain Aging in Insects

1986

The role of the central nervous system (CNS) in the modulation of homeostatic mechanisms and the aging process especially in mammals, has been well investigated by several authors (Blumenthal 1970, Ordy and Brizzee 1975, Hoffmeister and Muller 1979, Samorajski 1980, Buschmann 1982, Hoyer 1982, Frolkis et al. 1984). In insects the crucial role of the CNS in developmental processes is well established; however, it is an open question whether the brain also governs the aging processes.

Brain Structure MR Imaging Methods: Morphometry and Tractography

2013

Brain morphology is in constant change from the very beginning of the neurodevelopment in human beings. The characterization of the brain morphology and its biological implications on a specific subject is a complex task which requires efficient computational approaches. Radiology has traditionally assessed the main brain changes in different alterations from a macroscopic point of view, thus, not considering subtle changes as a results of neuronal plasticity. In conjunction with functional information, the structural neuroimaging methods have established as the key in the diagnosis of several central nervous system disorders, including tumours, neurodegenerative disorders and psychiatric d…

Die isolierte Fraktur des Hamulus ossis hamati - eine leicht zu übersehende Handwurzelverletzung

1993

Artificial Neural Network Based Abdominal Organ Segmentations: A Review

2015

There are many neural network based abdominal organ segmentation approaches from medical images. Computed tomography images were mostly used in these approaches. Applied techniques are usually based on prior information regarding position, shape, and size of organs in these methods. In the literature, there are only a few neural network based techniques that were implemented to segment abdominal organs from magnetic resonance based images. In this paper, we present these methods and their results.

Functional Magnetic Resonance Imaging (fMRI)

2017

Proton magnetic resonance imaging with para-hydrogen induced polarization.

2012

A major challenge in imaging is the detection of small amounts of molecules of interest. In the case of magnetic resonance imaging (MRI) their signals are typically concealed by the large background signal of e.g. the body. This problem can be tackled by hyperpolarization which increases the NMR signals up to several orders of magnitude. However, this strategy is limited for (1)H, the most widely used nucleus in NMR and MRI, because the enormous number of protons in the body screens the small amount of hyperpolarized ones. Here, we describe a method giving rise to high (1)H MRI contrast for hyperpolarized molecules against a large background signal. The contrast is based on the J-coupling i…

Direct radiofluorination of [18F]MH.MZ for 5-HT2A receptor molecular imaging with PET

2012

Imaging the serotonin 2A neuroreceptor with positron emission tomography has been carried out with [11C]MDL 100907 and [18F]altanserin for years. Recently, the MDL 100907 analogue [18F]MH.MZ was developed by combining the increased selectivity profile of MDL 100907 and the favourable radiophysical properties of fluorine-18. Here, we want to report the synthesis of [18F]MH.MZ via direct radiofluorination. Unfortunately, the direct radiofluorination did not have any significant benefits over the indirect labelling method. This is mainly because the precursor for the direct labelling approach is not completely stable and slowly decomposes. However, only one HPLC separation is necessary for the…

19F-MRI of perflubron for measurement of oxygen partial pressure in porcine lungs during partial liquid ventilation

2001

A method for in vivo measurement of oxygen partial pressure (pO2) in porcine lungs during partial liquid ventilation (PLV) with perflubron (PFOB) was developed. A pulse sequence for high-resolution MRI of the distribution of PFOB in the lung after intratracheal administration was developed as well. Moreover, quantitative measurements of longitudinal relaxation time T(1) of (19)F resonances for assessment of regional pO2 are described. Due to the need to acquire data during a single expiratory breathhold, only low SNRs were achieved in vivo. Therefore, simulations were performed to investigate the influence of background noise on T(1) values calculated from data with low SNR. Based on these …

Flip-angle measurement by magnetization inversion: Calibration of magnetization nutation angle in hyperpolarized 3 He magnetic resonance imaging lung…

2010

The aim of this work was to establish a new, fast, and robust method of flip-angle calibration for magnetic resonance imaging of hyperpolarized 3He. The method called flip-angle measurement with magnetization inversion is based on acquiring images from periodically inverted longitudinal magnetization created using the spatial modulation of magnetization technique. By measuring the width of the area where the magnetization was inverted by the spatial modulation of magnetization preparation in phase images, the flip angle can be generated using a simple equation. To validate and establish the limits of the proposed method, flip-angle measurement with magnetization inversion acquisitions were …

2020

Regular physical activity (PA) offers positive effects on the human body. However, the effects of PA on cognition and in the brain are less clear. In this paper, we narratively review the relationship of PA with cognition and dementia, first from general perspective and then through genetically informed studies on the topic. Then we move on to imaging studies on exercise and brain anatomy first by presenting an overall picture of the topic and then discussing brain imaging studies addressing PA and brain structure in twins in more detailed way. Regarding PA and cognition or dementia, genetically informed studies are uncommon, even though the relationship between PA and cognitive ageing has …