NMR angiography with enhanced quasi-half-echo scanning

Guo, Qi; Kashmar, G.; Nalcioğlu, Orhan

doi:10.1016/0730-725x(91)90001-3

Cited by 9 publications

(1 citation statement)

References 15 publications

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“…First and most important, they cannot accurately determine the degree of luminal stenosis in the presence of turbulent flow due to an artifactual darkening of regions within the lumen that can mimic complete vessel interruption. This phenomenon, which is commonly referred to as poststenotic signal loss, is a form of flow void that is caused by transverse magnetization incoherences (intravoxel phase dispersion) secondary to turbulent fluctuation velocities (1)(2)(3)(4)(5)(6)(7)(8). Second, since the WB-MRA contrast principle involves magnetization satura-tion of the static tissues surrounding the vessel, these techniques predominantly delineate the peripheral surface of the flowing blood and consequently provide limited information about the morphology and the internal characteristics of mural thrombus and plaque.…”

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confidence: 99%

Voxel sensitivity function description of flow‐induced signal loss in MR imaging: Implications for black‐blood MR angiography with turbo spin‐echo sequences

Jara

Caruthers

et al. 1999

Magn. Reson. Med.

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The conditions in which the image intensity of vessels transporting laminar flow is attenuated in black-blood MR angiography (BB-MRA) with turbo spin-echo (TSE) and conventional spin-echo (CSE) pulse sequences are investigated experimentally with a flow phantom, studied theoretically by means of a Bloch equation-voxel sensitivity function (VSF) formalism, and computer modeled. The experiments studied the effects of: a) flow velocity, b) imaging axes orientation relative to the flow direction , and c) phase encoding order of the TSE train. The formulated Bloch equation-VSF theory describes flow effects in two-dimensional (2D)-and 3D-Fourier transform magnetic resonance imaging. In this theoretical framework, the main attenuation mechanism instrumental to BB-MRA, i.e., transverse magnetiza-tion dephasing caused by flow in the presence of the imaging gradients, is described in terms of flow-induced distortions of the individual voxel sensitivity functions. The computer simulations predict that the intraluminal homogeneity and extent of flow-induced image intensity attenuation increase as a function of decreasing vessel diameter, in support of the superior image quality achieved with TSE-based BB-MRA in the brain. Magn Reson Med 41:575-590, 1999. 1999 Wiley-Liss, Inc.

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mentioning

confidence: 99%

Voxel sensitivity function description of flow‐induced signal loss in MR imaging: Implications for black‐blood MR angiography with turbo spin‐echo sequences

Jara

Caruthers

et al. 1999

Magn. Reson. Med.

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show abstract

Voxel sensitivity function description of flow-induced signal loss in MR imaging: Implications for black-blood MR angiography with turbo spin-echo sequences

Jara

Caruthers

et al. 1999

Magn. Reson. Med.

View full text Add to dashboard Cite

The conditions in which the image intensity of vessels transporting laminar flow is attenuated in black‐blood MR angiography (BB‐MRA) with turbo spin‐echo (TSE) and conventional spin‐echo (CSE) pulse sequences are investigated experimentally with a flow phantom, studied theoretically by means of a Bloch equation‐voxel sensitivity function (VSF) formalism, and computer modeled. The experiments studied the effects of: a) flow velocity, b) imaging axes orientation relative to the flow direction, and c) phase encoding order of the TSE train. The formulated Bloch equation‐VSF theory describes flow effects in two‐dimensional (2D)‐ and 3D‐Fourier transform magnetic resonance imaging. In this theoretical framework, the main attenuation mechanism instrumental to BB‐MRA, i.e., transverse magnetization dephasing caused by flow in the presence of the imaging gradients, is described in terms of flow‐induced distortions of the individual voxel sensitivity functions. The computer simulations predict that the intraluminal homogeneity and extent of flow‐induced image intensity attenuation increase as a function of decreasing vessel diameter, in support of the superior image quality achieved with TSE‐based BB‐MRA in the brain. Magn Reson Med 41:575–590, 1999. © 1999 Wiley‐Liss, Inc.

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Mechanisms of flow‐induced signal loss in MR angiography

Urchuk

Plewes

1992

Magnetic Resonance Imaging

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Mechanisms of signal loss in magnetic resonance angiography were studied with a stenotic flow phantom. The results indicate that while signal loss induced by mean fluid motions is localized about the stenosis, the fluctuating component of fluid motion induces signal loss over a much larger region, primarily distal to the stenosis. For both motion components, use of gradient moment nulling (GMN) above first order was found to be an ineffective means of reducing signal loss. In contrast, shortened gradient durations were found to reduce signal loss substantially. However, though a zeroth-order gradient is generally of the shortest duration, use of a slightly longer, first-order gradient was found to be the most robust means of reducing signal loss.

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NMR angiography with enhanced quasi-half-echo scanning

Cited by 9 publications

References 15 publications

Voxel sensitivity function description of flow‐induced signal loss in MR imaging: Implications for black‐blood MR angiography with turbo spin‐echo sequences

Voxel sensitivity function description of flow‐induced signal loss in MR imaging: Implications for black‐blood MR angiography with turbo spin‐echo sequences

Voxel sensitivity function description of flow-induced signal loss in MR imaging: Implications for black-blood MR angiography with turbo spin-echo sequences

Mechanisms of flow‐induced signal loss in MR angiography

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