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Acquisition Protocols (acquisition + protocol)
Selected AbstractsRadiation dose optimized lateral expansion of the field of view in synchrotron radiation X-ray tomographic microscopyJOURNAL OF SYNCHROTRON RADIATION, Issue 5 2010David Haberthür Volumetric data at micrometer level resolution can be acquired within a few minutes using synchrotron-radiation-based tomographic microscopy. The field of view along the rotation axis of the sample can easily be increased by stacking several tomograms, allowing the investigation of long and thin objects at high resolution. On the contrary, an extension of the field of view in the perpendicular direction is non-trivial. This paper presents an acquisition protocol which increases the field of view of the tomographic dataset perpendicular to its rotation axis. The acquisition protocol can be tuned as a function of the reconstruction quality and scanning time. Since the scanning time is proportional to the radiation dose imparted to the sample, this method can be used to increase the field of view of tomographic microscopy instruments while optimizing the radiation dose for radiation-sensitive samples and keeping the quality of the tomographic dataset on the required level. This approach, dubbed wide-field synchrotron radiation tomographic microscopy, can increase the lateral field of view up to five times. The method has been successfully applied for the three-dimensional imaging of entire rat lung acini with a diameter of 4.1,mm at a voxel size of 1.48,µm. [source] Predicting and monitoring cancer treatment response with diffusion-weighted MRIJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2010Harriet C. Thoeny MD Abstract An imaging biomarker that would provide for an early quantitative metric of clinical treatment response in cancer patients would provide for a paradigm shift in cancer care. Currently, nonimage based clinical outcome metrics include morphology, clinical, and laboratory parameters, however, these are obtained relatively late following treatment. Diffusion-weighted MRI (DW-MRI) holds promise for use as a cancer treatment response biomarker as it is sensitive to macromolecular and microstructural changes which can occur at the cellular level earlier than anatomical changes during therapy. Studies have shown that successful treatment of many tumor types can be detected using DW-MRI as an early increase in the apparent diffusion coefficient (ADC) values. Additionally, low pretreatment ADC values of various tumors are often predictive of better outcome. These capabilities, once validated, could provide for an important opportunity to individualize therapy thereby minimizing unnecessary systemic toxicity associated with ineffective therapies with the additional advantage of improving overall patient health care and associated costs. In this report, we provide a brief technical overview of DW-MRI acquisition protocols, quantitative image analysis approaches and review studies which have implemented DW-MRI for the purpose of early prediction of cancer treatment response. J. Magn. Reson. Imaging 2010. © 2010 Wiley-Liss, Inc. [source] Conventional MRI in Multiple SclerosisJOURNAL OF NEUROIMAGING, Issue 2007Massimo Filippi MD ABSTRACT During the past 10 years, conventional magnetic resonance imaging (cMRI) has become an established tool for the assessment of patients with multiple sclerosis (MS) and to monitor treatment trials. This is mainly due to the sensitivity and reproducibility of cMRI in the detection of MS-related damage. A large effort has also been devoted to develop imaging strategies capable of providing accurate estimates of the extent of disease-related damage not only in the brain, but also in the spinal cord and optic nerve. Guidelines have been defined to integrate MR findings in the diagnostic evaluation of patients at presentation with clinically isolated syndromes suggestive of MS, and specific acquisition protocols have been offered for monitoring longitudinal changes in patients with established disease. Despite the fact that the role of cMRI in MS has been profoundly obviated by the advent of modern and quantitative MR techniques, several issues are still unresolved. Technical development in acquisition and postprocessing, as well as the introduction of high-field magnets in the clinical arena, are likely to increase our understanding of disease pathobiology, mainly through an increased ability to quantify the extent of gray matter damage. [source] MRI of atherosclerosis in clinical trialsNMR IN BIOMEDICINE, Issue 6 2006Chun Yuan Abstract Magnetic resonance imaging (MRI) of the arterial wall has emerged as a viable technology for characterizing atherosclerotic lesions in vivo, especially within carotid arteries and other large vessels. This capability has facilitated the use of carotid MRI in clinical trials to evaluate therapeutic effects on atherosclerotic lesions themselves. MRI is specifically able to characterize three important aspects of the lesion: size, composition and biological activity. Lesion size, expressed as a total wall volume, may be more sensitive than maximal vessel narrowing (stenosis) as a measure of therapeutic effects, as it reflects changes along the entire length of the lesion and accounts for vessel remodeling. Lesion composition (e.g. lipid, fibrous and calcified content) may reflect therapeutic effects that do not alter lesion size or stenosis, but cause a transition from a vulnerable plaque composition to a more stable one. Biological activity, most notably inflammation, is an emerging target for imaging that is thought to destabilize plaque and which may be a systemic marker of vulnerability. The ability of MRI to characterize each of these features in carotid atherosclerotic lesions gives it the potential, under certain circumstances, to replace traditional trials involving large numbers of subjects and hard end-points , heart attacks and strokes , with smaller, shorter trials involving imaging end-points. In this review, the state of the art in MRI of atherosclerosis is presented in terms of hardware, image acquisition protocols and post-processing. Also, the results of validation studies for measuring lesion size, composition and inflammation will be summarized. Finally, the status of several clinical trials involving MRI of atherosclerosis will be reviewed. Copyright © 2006 John Wiley & Sons, Ltd. [source] Application of automated matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the measurement of enzyme activitiesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 15 2001Min-Jung Kang Sample preparation methods and data acquisition protocols were optimized for the application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) to high-throughput quantitative analysis of low molecular mass substrates and products of an enzyme-catalyzed reaction. Using a deuterlum-labeled internal standard, precise standard curves were obtained (r2,=,0.9998) over two orders of magnitude of concentration of rac -1-phenylethylamine (PEA), which is converted to 2-methoxy- N -[(1R)-1-phenylethyl]acetamide (MET) by a lipase-catalyzed reaction with ethylmethoxyacetate (EMA) as second substrate. Reliable relative standard deviations were achieved (,5%) using automated analysis with peak intensity ratios between 0.2 and 5 of analyte to internal standard. This method permitted quantitative analysis of the lipase reaction, producing results comparable to those from gas chromatographic (GC) analysis in the dynamic range of GC. This work shows that MALDI-TOFMS can be applied for the high-throughput screening of enzymes. Copyright © 2001 John Wiley & Sons, Ltd. [source] | |||||||||||||