Abstract:
:Spatiotemporally structured noise, such as physiological noise, is a potential source of artifacts in functional magnetic resonance imaging (fMRI) and is the main limiting factor for the detection of small blood oxygen level-dependent (BOLD) signal variations. fMRI was employed to detect low-frequency BOLD signal fluctuations, which are thought to be related to spontaneous neuronal activity in the resting human brain. The sensitivity to noise, that is, signal variations of non-BOLD origin, was investigated for two- (2D) and three-dimensional (3D) imaging techniques. Incomplete relaxation between subsequent scans increases the level of temporally and spatially correlated signal variations originating from physiological and/or systemic noise. Although inflow effects are suspected to be reduced in 3D echo-planar imaging (EPI) compared with multi-slice 2D EPI, the noise level was higher in the 3D technique. The noise level in 3D fMRI experiments was significantly increased by instabilities of the transverse steady-state magnetization as the repetition time was of the order of T(2). By implementing radiofrequency spoiling, temporal signal fluctuations and erroneous inter-regional correlation in connectivity maps were diminished to a level present in data sets acquired with 2D EPI.
journal_name
NMR Biomedjournal_title
NMR in biomedicineauthors
Goerke U,Möller HE,Norris DG,Schwarzbauer Cdoi
10.1002/nbm.987subject
Has Abstractpub_date
2005-12-01 00:00:00pages
534-42issue
8eissn
0952-3480issn
1099-1492journal_volume
18pub_type
杂志文章abstract::Wilms' tumours (WTs) are large heterogeneous tumours, which typically consist of a mixture of histological cell types, together with regions of chemotherapy-induced regressive change and necrosis. The predominant cell type in a WT is assessed histologically following nephrectomy, and used to assess the tumour subtype ...
journal_title:NMR in biomedicine
pub_type: 临床试验,杂志文章
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pub_type: 杂志文章
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journal_title:NMR in biomedicine
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abstract:INTRODUCTION:Sarcoidosis is a systemic granulomatous disease affecting in particular the respiratory tract. Cardiac magnetic resonance (CMR), including a measurement of T1 relaxation time, could potentially detect early stadia of sarcoidosis of the heart. The study aims to assess T1 mapping in the detection of early ca...
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pub_type: 杂志文章
doi:10.1002/nbm.4388
更新日期:2020-11-01 00:00:00
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journal_title:NMR in biomedicine
pub_type: 杂志文章,评审
doi:10.1002/nbm.1177
更新日期:2007-11-01 00:00:00
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journal_title:NMR in biomedicine
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更新日期:2006-02-01 00:00:00
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pub_type: 杂志文章
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更新日期:2007-08-01 00:00:00
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journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.2883
更新日期:2013-04-01 00:00:00
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journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/(SICI)1099-1492(199610)9:7<297::AID-NBM433
更新日期:1996-10-01 00:00:00
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更新日期:2014-02-01 00:00:00
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