Hypercapnia‐induced effects on image contrast based on intermolecular double‐quantum coherences

Schäfer, Andreas; Zysset, Stefan; Heinke, Wolfgang; Möller, Harald E.

doi:10.1002/mrm.21768

Cited by 4 publications

(2 citation statements)

References 37 publications

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“…To such principle, it can be predicted that quantification of DTI parameters might be interfered by the presence of cerebral vasculature which would contaminate the diffusion signals from cellular fluid as well as other pathology-derived diffusivity changes [17][18][19][20][21]. However, the degree of blood signal from vasculature affects diffusivity has not been verified yet.…”

Section: Introductionmentioning

confidence: 94%

The effects of hypercapnia on DTI quantification in anesthetized rat brain

Ding

Hui

2009

2009 Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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Diffusion Tensor Imaging (DTI) offers a valuable in vivo tool to characterize water diffusion behavior in biological tissues, particularly brain tissues. The accuracy of DTI derived parameters can directly affect the interpretation of underlying microstructures, physiology or pathologies. It is anticipated that measurement of apparent diffusion coefficient (ADC) using DTI could be influenced and complicated by the presence of water molecules in brain vasculature. However, little is known about to what degree does blood signal from vasculature affect the diffusion quantitation. In this study, we examined the effects of hypercapnia on DTI quantification in rat brains using inhalation of 5% carbon dioxide (CO2). It was found that statistically significant changes occurred in parametric DTI maps in response to cerebrovascular challenges, indicating that vascular factors could interfere with in vivo DTI characterization of neural tissues. Consequently, hemodynamic alterations can potentially affect the DTI quantitation and detection of tissue microstructures and pathological alterations. Therefore, cautions must be taken when interpreting DTI parameters in vivo.

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Section: Introductionmentioning

confidence: 94%

The effects of hypercapnia on DTI quantification in anesthetized rat brain

Ding

Hui

2009

2009 Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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“…Intermolecular multiple quantum coherences (iMQCs) originated from distant dipolar field (DDF) possess numerous interesting properties (1–3). They have been developed for many important applications in spectroscopy (4, 5) and imaging (2, 6–9). However, a more general utilization of iMQCs is hindered by the poor signal‐to‐noise ratio inherent to current methodologies (10).…”

mentioning

confidence: 99%

Highly efficient square wave distant dipolar field and its application for in vivo MRI

Cai¹,

Gao²,

Cai³

et al. 2010

Magnetic Resonance in Med

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Intermolecular multiple quantum coherences generated by distant dipolar field (DDF) have some attractive properties, but the intrinsic weak signal intensity prevents their widespread applications. Recently, Branca et al. (J Chem Phys 2008;129:054502) suggested that square wave DDF was more efficient than conventional sinusoidal DDF because it could simultaneously produce intermolecular multiple quantum coherences signal with various major orders. In this article, instead of a series of adiabatic inversion pulses proposed previously, a more efficient composite adiabatic inversion pulse was applied to create square wave DDF. The square wave DDF was applied to in vivo MRI for the first time, and the corresponding simulations were performed. Both experimental and simulated results show that square wave DDF with composite adiabatic inversion pulse improves over the original Z-modulation enhanced to binary for self-refocused acquisition implementation and can enhance the signal intensity to about 2-fold of that from conventional correlation spectroscopy (COSY) revamped with asymmetric Z-gradient echo detection sequence for in vivo MRI, close to the theoretical prediction. Magn Reson Med 64:1128-1134, 2010. V C 2010 Wiley-Liss, Inc. Key words: magnetic resonance imaging; signal enhancement; intermolecular double-quantum coherence; distant dipolar field; square wave modulation Intermolecular multiple quantum coherences (iMQCs) originated from distant dipolar field (DDF) possess numerous interesting properties (1-3). They have been developed for many important applications in spectroscopy (4,5) and imaging (2,6-9). However, a more general utilization of iMQCs is hindered by the poor signal-tonoise ratio inherent to current methodologies (10). This problem is especially serious for clinical MRI, which is often operated at a relatively low field because the iMQC signal scales as the square of magnetization density, which in turn is proportional to the magnetic field strength. Several methods have been suggested recently to improve the signal-to-noise ratio of iMQC signals (11,12).In almost all published results to date, the DDF in all kinds of iMQC applications came from magnetization sinusoidally modulated in space by coherence selection gradients (6). Recently, Branca and coworkers (13) suggested using square wave DDF to enhance the iMQC signal intensity. A variant of correlation spectroscopy (COSY) revamped with asymmetric Z-gradient echo detection (CRAZED) sequence was proposed, which was called Z-modulation enhanced to binary for selfrefocused acquisition (ZEBRA) sequence (Fig. 1b,c). The basic strategy of this method is to convert the equilibrium magnetization into stripes (a square wave) instead of sinusoidal modulation used in the original CRAZED and similar sequences. Signals of different coherence orders can be obtained simultaneously with the sequence. A series of slice-selective off-resonance inversion pulses were applied to convert the equilibrium magnetization into stripes, which was realized experimentally...

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