Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine
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Ultrafast sequences based on "Hybrid" spatiotemporal encoding (SPEN) replace echo-planar imaging's phase encoding "blips," while retaining a k-space readout acquisition. Hardware imperfections during acquisition may lead to ghosts and striped artifacts along the SPEN dimension; akin to echo-planar imaging's Nyquist ghosts, but weaker. A referenceless method to eliminate these artifacts in Hybrid SPEN is demonstrated. ⋯ The referenceless correction enables robust single-scan imaging under changing conditions-such as patient motion and changes in shimming over time-without the need of ancillary navigators. This opens new options for real-time MRI and interactive scanning.
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MR histology based on magnetic susceptibility can be used to visualize diamagnetic myelin (and its deterioration) in the central nervous system and is facilitated by the application of high magnetic field strengths and paramagnetic contrast agents. Characterizing the effect of these tools will aid in assessing white matter myelin content and microstructure. ⋯ Using contrast agents in MR histology facilitates white-gray matter susceptibility contrast modulation and the probing of white matter microstructure and orientation.
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Randomized Controlled Trial
Whole-brain three-dimensional T2-weighted BOLD functional magnetic resonance imaging at 7 Tesla.
A new acquisition scheme for T2-weighted spin-echo BOLD fMRI is introduced. ⋯ This approach is expected to be useful for ultra-high field fMRI, especially for regions near air cavities. The concept of using T2-preparation to generate BOLD contrast can be combined with many other sequences at any field strength.
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In this study, we aim to demonstrate the sensitivity of proton resonance frequency shift (PRFS) -based thermometry to heat-induced magnetic susceptibility changes and to present and evaluate a model-based correction procedure. ⋯ This study has shown the effects of magnetic susceptibility changes induced by heating of breast fatty tissue samples. The resultant errors can be reduced by the use of a model-based correction procedure.
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Magnetic resonance imaging (MRI), specifically late-enhanced MRI, is the standard clinical imaging protocol to assess cardiac viability. Segmentation of myocardial walls is a prerequisite for this assessment. Automatic and robust multisequence segmentation is required to support processing massive quantities of data. ⋯ The experimental validation with two magnetic resonance sequences demonstrates increased accuracy and versatility.