meta-DENSE complex acquisition for reduced intravoxel

Individuell kartläggning av hjärnan, ett fmri-datasæt med hög

(1999) Chen, Wyrwicz. Magnetic Resonance in Medicine. A technique is proposed to compensate for the slice dephasing artifact and improve the signal-to-noise ratio (SNR) of gradient-echo images. In MRI, intravoxel dephasing causes signal loss in regions of magnetic field inhomogeneity and at interfaces of tissues having different magnetic susceptibilities. In MRA, signal loss due to intravoxel dephasing also occurs when nuclei having different velocities are present in the same voxel. of intravoxel dephasing among flowing spins that have large intravoxel veloc-ity variability.

Intravoxel dephasing

However, distribution of smaller magnetic particles over a PURPOSE: In 3D gradient echo magnetic resonance imaging (MRI), strong field gradients B0macro are visually observed at air/tissue interfaces. At low spatial resolution in particular, the respective field gradients lead to an apparent increase in intravoxel dephasing, and subsequently, to signal loss or inaccurate R2* estimates. Moreover, the difference in magnetic susceptibility ([chi]) of tumors and normal tissues accelerates intravoxel dephasing of transverse magnetization in tumor and creates off-resonance effects or [T.sup.*sub.2] contrast, a combination of spin-spin relaxation ([T.sub.2]) and [B.sub.0] magnetic field inhomogeneity. On the other hand, intravascular-dephasing effects scale with dHb concentration and are therefore most prominent in the draining veins.

Individuell kartläggning av hjärnan, ett fmri-datasæt med hög

/ Aletras, Anthony; Arai, A E. In: Journal of Magnetic Resonance, Vol. 169, No. 2, 2004, p. 246-249.

Software Simulation of Magnetic Resonance Imaging - Ca Da Alt N

Figure 2 a) linear PE, b) meta-DENSE complex acquisition for reduced intravoxel dephasing. Aletras, Anthony LU and Arai, A E ( 2004 ) In Journal of Magnetic Resonance 169 (2) . p.246-249 Mark A technique is proposed to compensate for the slice dephasing artifact and improve the signal‐to‐noise ratio (SNR) of gradient‐echo images. This method is composed of two components: mapping of the internal gradient and design of the slice‐selective radiofrequency (RF) pulse.

During the last decade modern scanners have overcome these limitations making bSSFP a viable and useful sequence on most mid- and high-field systems. Start Forskningsoutput meta-DENSE complex acquisition for reduced intravoxel dephas meta-DENSE complex acquisition for reduced intravoxel dephasing. Signal loss due to flow is induced via intravoxel dephasing which, according to Eq. 1, is dependent on velocity profile and m1. For a certain velocity profile, the flow suppression capability of FSD-preparation is determined by m1. Haacke et al.
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Each cylinder contributed to the intravoxel dephasing and associated signal loss occurring in the ROI ROI MGL decay on simulated and experimental images for the network of air-filled cylinders. Intravoxel dephasing causes signal loss and thus intensity attenuation in the images. The new rephasing factor we introduce, which changes the intensity of a voxel in images during the registration, is used to improve the accuracy of the intensity-based nonrigid registration method and mitigate the intensity attenuation effect.

A new sequence incorporating velocity-dependent slice excitation and ultrashort TE (UTE) centric radial readout trajectories is proposed that reduces TE from 2.85 to 0.65 ms. How to decrease intravoxel dephasing and increase SNR: Decrease the voxel size (increase spatial resolution), either by increasing the matrix (trade-off: will reduce signal-to-noise ratio ) or by reducing the FOV (trade-off: may cause wraparound). Only gold members can continue reading.
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meta-DENSE complex acquisition for reduced intravoxel

Signal decay over echo time was assessed at different pixel sizes on real and simulated images. This dephasing is due to static magnetic field inhomogeneities intrinsic (i.e.

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Real-time fMRI Biofeedback Targeting the Orbitofrontal Cortex

The arterial images with suppressed background and venous signals were obtained by means of sub-traction of a dark artery measurement (Fig 1, A) and a bright artery measure-ment (Fig 1, B), both of which were in one single image. The bright artery and Displacement encoding with stimulated echoes (DENSE) with a meta-DENSE readout and RF phase cycling to suppress the STEAM anti-echo is described for reducing intravoxel dephasing signal loss. This RF phase cycling scheme, when combined with existing meta-DENSE suppression of the T1 recovering signal, yields higher quality DENSE myocardial strain maps.