نتایج جستجو برای: gradient echo sequences
تعداد نتایج: 358924 فیلتر نتایج به سال:
Steady-state sequences are a class of rapid magnetic resonance (MR) imaging techniques based on fast gradient-echo acquisitions in which both longitudinal magnetization (LM) and transverse magnetization (TM) are kept constant. Both LM and TM reach a nonzero steady state through the use of a repetition time that is shorter than the T2 relaxation time of tissue. When TM is maintained as multiple ...
PURPOSE To investigate the utility of dynamic contrast-enhanced gradient-echo MR imaging of head and neck lesions and to compare this technique with the commonly used spin-echo contrast-enhanced fat-saturation technique. METHODS Twenty-two patients with a total of 23 head and neck neoplasms underwent dynamic gradient-echo and spin-echo MR imaging studies. The spin-echo and dynamic gradient-ec...
PURPOSE To assess the most effective magnetic resonance imaging (MRI) sequence for the visualization of the 9th, 10th, and 11th cranial nerves (glossopharyngeal, vagus, and accessory nerves, respectively) in their intraforaminal/canalicular courses. MATERIALS AND METHODS Balanced fast-field echo (b-FFE), 3D-T2W DRIVE, T2W 2D TSE and post-contrast T1W MRI sequences were all applied and we trie...
BACKGROUND AND PURPOSE A novel quantitative susceptibility mapping (QSM) processing technology has been developed to map tissue susceptibility property without blooming artifacts. We hypothesize that hematoma volume measurement on QSM is independent of imaging parameters, eliminating its echo time dependence on gradient echo MRI. METHODS Gradient echo MRI of 16 patients with intracerebral hem...
Accurate assessment of myocardial viability is a central goal in clinical diagnosis of ischemic heart disease, as well as in basic research into the underlying mechanisms of cardiac pathology. Clinical assessment of myocardial viability would have a significant impact on the management of patients with ischemic heart disease, by avoiding unnecessary revascularization procedures, as well as asse...
Background: Hypointense lesions on T1-weighted images have important clinical relevance in multiple sclerosis patients. Traditionally, spin-echo (SE) sequences are used to assess these (termed black holes), but Fast Spoiled Gradient-Echo (FSPGR) provide an excellent alternative. Objective: To determine whether the contrast difference between T1 hypointense and surrounding normal white matter is...
Conventional functional magnetic resonance imaging (fMRI) technique known as gradient-recalled echo (GRE) echo-planar imaging (EPI) is sensitive to image distortion and degradation caused by local magnetic field inhomogeneity at high magnetic fields. Non-EPI sequences such as spoiled gradient echo and balanced steady-state free precession (bSSFP) have been proposed as an alternative high-resolu...
Background When imaging the airway by MRI, the traditional technique turbo spin echo (TSE) results in high quality 2D images of the airway. However, planning and acquisition times are often lengthy. An alternative technique for airway image acquisition, delayed volume interpolated breath hold examination or VIBE, is a 3D gradient echo technique that produces high spatial resolution imaging of t...
A novel spin-echo-based refocusing strategy called a hyperecho mechanism is introduced by which the full coherence of magnetization submitted to a sequence of arbitrary RF pulses can be reinstalled. First implementations illustrate the potential of hyperecho formation-especially for Rapid Acquisition with Relaxation Enhancement (RARE) imaging, in which the full image intensity can be retrieved ...
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