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Magnetic resonance imaging (MRI) plays an important role in research on Alzheimers disease (AD). This includes studies in both transgenic mouse models as well as in humans. In this special hot topic issue in CMIR we aim to give an overview on “Prospects of Magnetic Resonance Imaging for Alzheimers Disease”. This issue has been classified into three main sections based on the type of MRI methods exploited in the field of AD: (1) Structural MRI, (2) Vascular MRI and (3) MR spectroscopy. In this way the issue provides a comprehensive coverage of the applications of MRI for AD. STRUCTURAL MRI Using structural MRI methods, two types of information can be generated in AD in vivo: changes induced by specific histological hallmarks of AD (amyloid plaques) on the one hand, and specific tissue changes (atrophy) that are associated with AD on the other hand. This section includes three papers on qualitative and three on quantitative structural MRI methods. Imaging of amyloid plaques is one of the current challenges of MRI in the field of Alzheimers disease. In qualitative structural MRI sub-section, Ryan Chamberlain and co workers focus on advances made in visualization of amyloid beta (A) plaques with magnetic resonance imaging using different lines of transgenic mouse models of AD with emphasis on the recent longitudinal studies that enabled the visualization of plaque development in the same animals with age and their future impact on drug discovery. In addition, potential applications and challenges in the translation of these methods for visualizing plaques in humans are discussed. Alexandra Petiet and Marc Dhenain present an overview of plaque visualization using MR contrast agent. They also discuss the current issues related to amyloid specific and non-specific contrast agents such as their concentrations and difficulties to pass through the blood brain barrier. In addition to plaque visualization, the axonal function can be evaluated by structural MRI tools. Zaim Wadghiri and Anne Bertrand discuss the use of manganese enhanced MRI for in vivo evaluation of axonal function in transgenic mouse model of AD. Kejal Kantarci and colleagues discuss the application of diffusion tensor imaging as a sensitive, quantitative, tool to get access to the tissue microstructures, such as the disruption of myelin and axons in the white matter and neuronal cell bodies in the grey matter during the progression of AD. The quantitative measurements of regional atrophy in MR images and its application to AD diagnosis are reviewed by Faiza Admiraal-Behloul and co-workers. The prospective of mathematical modeling and feature extraction in MR images for probing crucial quantitative changes associated with AD is discussed by Michael Muskulus and Sjoerd Verduyn Lunel. VASCULAR MRI Vascular abnormalities are commonly observed in association with the parenchymal changes in AD. Nicolau Beckmann discusses the use of MRI to detect cerebrovascular alterations in both mouse models and in human patients. Application of cerebral blood volume measurements, arterial spins labeling for perfusion assessment, and MR angiography for probing vascular architecture are addressed. Arterial spins labeling (ASL) provides a non-invasive measurement of cerebral blood flow at a very high resolution by magnetically labeling the blood in the main brain-feeding arteries and subsequently detecting the labeled spins in the cerebral tissue after a delay. The use of arterial spin labeling perfusion MRI in AD is discussed in detail by Matthias van Osch and Hanzhang Lu. The added value of ASL perfusion studies and its future prospective for distinguishing between AD and other forms of dementia is critically reviewed by Norbert Schuff. MR SPECTROSCOPY Magnetic resonance spectroscopy (MRS) is a powerful tool for non invasive monitoring of the disease progression at a molecular level. Longitudinal and non-longitudinal single voxel MRS studies in AD patients and transgenic mouse models are summarised by Firat Kara and co-workers. The potential use of MRS for therapeutic studies in AD mice is also discussed. Furthermore, the future prospective in using 2D MRS for unearthing new biomarkers of AD is addressed. Chemical shift imaging has the ability to simultaneously measure metabolite concentrations in multiple areas of the brain. Although CSI has been available for nearly a decade, it has not been widely used for AD research. Christopher Scott and co-workers present an introduction to chemical shift imaging and examined the current state of chemical shift imaging in the investigation of AD and highlights the technological advances that will drive future developments and its applications to AD. CONCLUDING COMMENTS The organization of this special issue on “Prospects of Magnetic Resonance Imaging for Alzheimers Disease” began with the idea of making a special effort to compile the scattered information into a full comprehensive journal issue on the application of MRI to AD. In this special issue a number of experts have written papers reviewing the application of MRI to AD and further discuss the future prospects of using MRI for improved diagnosis and prediction of AD. Every paper underwent a standard peer review by two independent referees, in addition to review by one of the Guest Editors or the Editor-in-Chief. We hope that the article in this special issue can form a useful reference and will help to stimulate and disseminate further research and clinical applications of MRI for diagnosis and understanding the AD and its widespread adoption into clinical practice. |
