نتایج جستجو برای: bold signal

تعداد نتایج: 426650  

Journal: :iranian journal of medical physics 0
mohammad ali oghabian neuroimaging and analysis group, research center of molecular and cellular imaging, tehran university of medical sciences, tehran, iran

introduction echo-planar imaging (epi) is a group of fast data acquisition methods commonly used in fmri studies. it acquires multiple image lines in k-space after a single excitation, which leads to a very short scan time. a well-known problem with epi is that it is more sensitive to distortions due to the used encoding scheme. source of distortion is inhomogeneity in the static b0 field that ...

Journal: :iranian journal of medical physics 0
ali mirzajani optometry department, rehabilitation faculty, tehran university of medical sciences, tehran, iran. medical physics department, tehran university of medical sciences, tehran, iran

introduction as functional magnetic resonance imaging (fmri) is too expensive and time consuming, its frequent implementation is difficult. the aim of this study is to evaluate repeatability of detecting visual cortex activity in fmri. materials and methods in this study, 15 normal volunteers (10 female, 5 male; mean age±sd: 24.7±3.8 years) attended. functional magnetic resonance images were ob...

2018
Alexander D Cohen Andrew S Nencka Yang Wang

Typical simultaneous blood oxygenation-level dependent (BOLD) and arterial spin labeling (ASL) sequences acquire two echoes, one perfusion-sensitive and one BOLD-sensitive. However, for ASL, spatial resolution and brain coverage are limited due to the T1 decay of the labeled blood. This study applies a sequence combining a multiband acquisition with four echoes for simultaneous BOLD and pseudo-...

Journal: :Journal of Magnetic Resonance Imaging 2006

Journal: :Annual review of physiology 2004
Nikos K Logothetis Brian A Wandell

The development of functional magnetic resonance imaging (fMRI) has brought together a broad community of scientists interested in measuring the neural basis of the human mind. Because fMRI signals are an indirect measure of neural activity, interpreting these signals to make deductions about the nervous system requires some understanding of the signaling mechanisms. We describe our current und...

Journal: :EURASIP Journal on Advances in Signal Processing 2009

Journal: :AJNR. American journal of neuroradiology 2003
Paul J Laurienti Aaron S Field Jonathan H Burdette Joseph A Maldjian Yi-Fen Yen Dixon M Moody

BACKGROUND AND PURPOSE Recent interest has emerged in the use of pharmacologic methods to maximize blood oxygenation level-dependent (BOLD) signal intensity changes in functional MR imaging (fMRI). Adenosine antagonists, such as caffeine and theophylline, have been identified as potential agents for this purpose. The present study was designed to determine whether caffeine-induced decreases in ...

Journal: :Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism 2002
Noam Harel Sang-Pil Lee Tsukasa Nagaoka Dae-Shik Kim Seong-Gi Kim

Functional magnetic resonance imaging (fMRI) techniques are based on the assumption that changes in spike activity are accompanied by modulation in the blood oxygenation level-dependent (BOLD) signal. In addition to conventional increases in BOLD signals, sustained negative BOLD signal changes are occasionally observed and are thought to reflect a decrease in neural activity. In this study, the...

Introduction As functional magnetic resonance imaging (fMRI) is too expensive and time consuming, its frequent implementation is difficult. The aim of this study is to evaluate repeatability of detecting visual cortex activity in fMRI. Materials and Methods In this study, 15 normal volunteers (10 female, 5 male; Mean age±SD: 24.7±3.8 years) attended. Functional magnetic resonance images were ob...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید