弯弯曲曲
发表于 2025-3-26 21:13:09
Introduction,t NIH and at the Centre for Magnetic Resonance Research in Minnesota (CMRR). For more than a decade, the research teams working on these systems produced a constant stream of papers on the benefits, and the challenges of high field MR. Some of the early work—most notably early results on fMRI at 4T
PAN
发表于 2025-3-27 04:51:05
High-Field Superconducting Magnets,medical diagnosis and many kinds of scientific research. MRI and MRS, however, remain fields characterized by a great deal of innovation. The main goal of this innovation is the improvement in the basic signal to noise ratio. One way whereby the signal to noise ratio can be improved is by increasing
amnesia
发表于 2025-3-27 07:10:29
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Grievance
发表于 2025-3-27 11:37:37
Radiofrequency Coils,gnificantly less than the body dimensions. An associated problem is the spatially inhomogeneous electric field that can produce localized thermal hot-spots. The use of transmit array coils, in which the magnitude and phase of the inputs to each element of the array are individually controlled, can s
Diskectomy
发表于 2025-3-27 16:54:17
Safety,g, and the radiofrequency fields used for signal transmission. The physical mechanisms are identical to those at conventional MR. Exposure levels in UHF-MR nevertheless reach values of concern necessitating appropriate measures to ensure safety of patients, volunteers, and operating and technical pe
伤心
发表于 2025-3-27 19:17:35
Contrasts, Mechanisms and Sequences,ging systems and clinical MRI. The obvious motivation is the higher signal-to-noise ratio achievable. However, other effects that result from changes in the relaxation times, the ratio of the object extensions with respect to the RF wave length, or the deposited energy have to be considered. The bas
怕失去钱
发表于 2025-3-27 23:51:05
What to do with All that Signal? Issues of High-resolution MRI,neity and SAR, has been given in ., together with some of the consequences and remedies for major MR imaging methods. In this chapter, a few general aspects and possible exploitations of the increased SNR at high field are described. In addition, limitations of improvements at high field strength an
Firefly
发表于 2025-3-28 03:45:23
Neuroscientific Applications of High-Field MRI in Humans,e. Neuroscientists are interested in the spatial organisation of brain grey matter, in cortex and deep brain structures, and in the connectivity of white matter neuronal fibres. At lower field, it is very hard to distinguish cortical areas purely by their anatomical differences, or to discriminate s
photophobia
发表于 2025-3-28 06:58:40
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NICE
发表于 2025-3-28 13:19:05
Oncology,ponse and early detection of recurrence. For all applications high field MRI can be advantageous, because the spatial resolution of the MR images is increasing with field strength, and thus smaller lesions become detectable. Furthermore, functional imaging techniques benefit from the higher field st