نتایج جستجو برای: gradient echo sequences

تعداد نتایج: 358924  

Journal: :AJNR. American journal of neuroradiology 2015
A E Tyan A M McKinney T J Hanson C L Truwit

SUMMARY A prior clinical report of 3T MR imaging in subsequently healthy very premature neonates imaged at term-equivalent age found that both gradient recalled-echo-T1WI and spin-echo-T2WI showed higher rates of myelinated structures, compared with spin-echo-T1WI. The current study set out to assess those rates on the same sequences at 3T in term neonates and thus consisted of 16 term neonates...

Journal: :Archives of neurology 2005
Fritz-Georg Lehnhardt Ulrich von Smekal Benedikt Rückriem Werner Stenzel Michael Neveling Wolf-Dieter Heiss Andreas H Jacobs

BACKGROUND Cerebral cavernous malformations (CCMs) are congenital vascular anomalies that can cause seizures, intracranial hemorrhages, focal neurological deficits, and migrainelike headaches. Magnetic resonance (MR) imaging has substantially facilitated diagnosis of CCM. It is now widely accepted that familial clustering with an autosomal dominant inheritance pattern should be suspected in cas...

Journal: :AJNR. American journal of neuroradiology 1988
J F Norfray J R Couch R J Elble D C Good B V Manyam J L Patrick

Brain iron was visualized on a mid-field (0.5 T) scanner using a spin-echo pulse sequence. Methemoglobin was hyperintense on T1- and T2-weighted images. Deoxyhemoglobin, hemosiderin, and ferritin were seen as decreased intensity on T2-weighted images. The spin-echo pulse sequences were improved for identification of deoxyhemoglobin, hemosiderin, and ferritin by prolonging the TR to 3000 msec an...

2009
I. Drobnjak B. Siow D. C. Alexander

Introduction: Measuring microstructure parameters of brain tissue, such as axon radius, in vivo is a challenge in diffusion MRI. Current approaches typically use pulsed-gradient spin-echo (PGSE) [1] or stimulated-echo (STEAM) [2] sequences, both of which use a rectangular diffusion-gradient pulse. However other shapes of diffusion-gradient pulses such as oscillating [3] or chirped [4] may provi...

Journal: :AJNR. American journal of neuroradiology 2002
Kei Yamada R Gilberto Gonzalez Leif ØStergaard Suzanne Komili Robert M Weisskoff Bruce R Rosen Walter J Koroshetz Tsunehiko Nishimura A Gregory Sorensen

BACKGROUND AND PURPOSE Age-related iron accumulation in extrapyramidal nuclei causes T2 shortening, which may result in decreased signal intensity in these areas on MR images. Because the dynamic susceptibility contrast-enhanced technique uses heavily T2*- or T2-weighted images, the iron-induced susceptibility may have direct impact on perfusion imaging. The purpose of this study was to assess ...

Journal: :NeuroImage 2005
Conny F Schmidt Peter Boesiger Alumit Ishai

In this study, we compared fMRI activation measured with gradient- and spin-echo-based fMRI during visual perception of faces, which is mediated by neural activation within a distributed cortical network. With both fMRI techniques, bilateral activation was observed in multiple regions including the inferior occipital gyrus, fusiform gyrus, superior temporal sulcus, amygdala, inferior frontal gy...

Journal: :Magnetic resonance in medicine 2003
Klaus Scheffler Jürgen Hennig

It is commonly accepted that TrueFISP (balanced FFE, FIESTA) belongs to the class of gradient-echo (GRE) sequences. GRE sequences are sensitive to dephasing effects of the transverse magnetization between the excitation pulse and echo acquisition, and phase coherence is only established directly after and before excitation pulses. However, an analysis of the phase evolution of transverse magnet...

2010
John P Ridgway

There are many excellent specialised texts and articles that describe the physical principles of cardiovascular magnetic resonance (CMR) techniques. There are also many texts written with the clinician in mind that provide an understandable, more general introduction to the basic physical principles of magnetic resonance (MR) techniques and applications. There are however very few texts or arti...

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