Sodium MR Imaging of Acute and Subacute Stroke for Assessment of Tissue Viability

Thulborn, Keith R.; Davis, Denise; Snyder, James V.; Yonas, Howard; Kassam, Amin

doi:10.1016/j.nic.2005.08.003

Cited by 104 publications

(102 citation statements)

References 24 publications

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“…The potential diagnostic benefits of 23 Na-MR imaging have recently been demonstrated for common pathological conditions such as tumor [5,6], stroke [7][8][9], Alzheimer disease [10], paramyotonia [11], arthritis [12], multiple sclerosis [13] and functional renal imaging [14] in humans. In addition, pre-clinical in vivo 23 Na MRI enables one to temporally follow pathological progression in animal models of common human disease [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

The design of a double-tuned two-port surface resonator and its application to in vivo Hydrogen- and Sodium-MRI

Wetterling

Högler

Molkenthin

et al. 2012

Journal of Magnetic Resonance

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The design and construction of a two-port surface transceiver resonator for both 1 H-and 23 Na-MRI in the rodent brain at 7T is described. Double-tuned resonators are required for accurately co-registering multi-nuclei data sets, especially when the time courses of 1 H and 23 Na signals are of interest as, for instance, when investigating the pathological progression of ischaemic stroke tissue in vivo. In the current study, a single-element two-port surface resonator was developed wherein both frequency components were measured with the same detector element but with each frequency signal routed along different output channels.This was achieved by using the null spot technique, allowing for optimal variable tuning and matching of each channel in situ within the MRI scanner. The 23 Na signal to noise ratio, measured in the ventricles of the rat brain, was increased by a factor of four compared to recent state-of-the-art rat brain studies reported in the literature. The resonator's performance was demonstrated in an in vivo rodent stroke model, where regional variations in 1 H apparent diffusion coefficient maps and the 23 Na signal were recorded in an interleaved fashion as a function of time in the acute phase of the stroke without having to exchange, re-adjust, or re-connect resonators between scans. Using the practical construction steps described in this paper, this coil design.

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Section: Introductionmentioning

confidence: 99%

The design of a double-tuned two-port surface resonator and its application to in vivo Hydrogen- and Sodium-MRI

Wetterling

Högler

Molkenthin

et al. 2012

Journal of Magnetic Resonance

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“…Brain neoplasia and sustained cell depolarization, a precursor of cell division, lead to an increase of the intracellular sodium concentration and to a rise in the average tissue sodium concentration (2). Furthermore, the application of sodium MRI has been shown to be valuable for muscular channelopathies (3,4), brain tumors (5), the human kidney (6), myocardial infarction (7), and cerebral ischemia (8,9) diagnostics.…”

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confidence: 99%

Sodium MRI using a density‐adapted 3D radial acquisition technique

Nagel

Laun

Weber

et al. 2009

Magnetic Resonance in Med

239

256

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A density-adapted three-dimensional radial projection reconstruction pulse sequence is presented which provides a more efficient k-space sampling than conventional three-dimensional projection reconstruction sequences. The gradients of the density-adapted three-dimensional radial projection reconstruction pulse sequence are designed such that the averaged sampling density in each spherical shell of k-space is constant. Due to hardware restrictions, an inner sphere of k-space is sampled without density adaption. This approach benefits from both the straightforward handling of conventional three-dimensional projection reconstruction sequence trajectories and an enhanced signal-to-noise ratio (SNR) efficiency akin to the commonly used three-dimensional twisted projection imaging trajectories. Benefits for low SNR applications, when compared to conventional three-dimensional projection reconstruction sequences, are demonstrated with the example of sodium imaging. In simulations of the point-spread function, the SNR of small objects is increased by a factor 1.66 for the densityadapted three-dimensional radial projection reconstruction pulse sequence sequence. Using analytical and experimental phantoms, it is shown that the density-adapted three-dimensional radial projection reconstruction pulse sequence allows higher resolutions and is more robust in the presence of field inhomogeneities. High-quality in vivo images of the healthy human leg muscle and the healthy human brain are acquired. For equivalent scan times, the SNR is up to a factor of 1.8 higher and anatomic details are better resolved using density-adapted three-dimensional radial projection reconstruction pulse sequence. Key words: sodium magnetic resonance imaging; densityadapted sampling; radial imaging; projection reconstruction; sampling density; field inhomogeneities Sodium ( 23 Na) ions play an important role in cellular homeostasis and cell viability. In healthy tissue, the extracellular sodium concentration ([Na ϩ ] ex ϭ 145 mM) is about 10 times higher than the intracellular concentration ([Na ϩ ] in ϭ 10-15 mM) (1). Using sodium MRI, volume-and relaxation-weighted signal of these compartments can be measured. Thus, sodium MRI is a promising diagnostic tool since pathologic processes can alter this ion gradient.Many studies investigating the usefulness of sodium MRI in human pathologies have been performed recently. Brain neoplasia and sustained cell depolarization, a precursor of cell division, lead to an increase of the intracellular sodium concentration and to a rise in the average tissue sodium concentration (2). Furthermore, the application of sodium MRI has been shown to be valuable for muscular channelopathies (3,4), brain tumors (5), the human kidney (6), myocardial infarction (7), and cerebral ischemia (8,9) diagnostics.However, sodium MRI remains a challenging technique for several reasons. The sodium nucleus exhibits a fast biexponential transversal relaxation in the extreme narrowing limit, i.e., if the correlation time is much shorter...

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“…In particular, quantitative 23 Na-MRI (qNa-MRI) shows promise for investigating and assessing such tissue changes over time in acute stroke (1).…”

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confidence: 99%

“…The ability to measure elevated 23 Na levels (7,8) and to accurately quantify the tissue sodium concentration (TSC-a measure related to combined intracellular and extracellular 23 Na concentrations) in humans using 23 Na-MRI has demonstrated considerable potential to provide such a direct marker for tissue viability in stroke (1,9). However, the clinical role of 23 Na-MRI in assessing stroke patients remains unclear, due primarily to the lack of temporally resolved 23 Na data in these studies coupled with the difficulty in correlating the TSC measurements in man with histological data, and consequently, 23 Na-MRI is not an established diagnostic technique in hospitals.…”

mentioning

confidence: 99%

“…Furthermore, to our knowledge, no study to date has succeeded in quantifying the TSC in different ischemic subregions (i.e., penumbra and core) during the early hours of stroke. 23 Na-MRI studies in animal stroke models have made use of a variety of models, including: the intraluminal thread model (13,14), direct middle cerebral artery occlusion (MCAO) with combined bilateral common carotid artery occlusion (11,13) in the rat, and autologous embolic MCAO models in rabbit (15) and nonhuman primate (1,9). These models induced different severities of ischemic insult, depending on the addition of common carotid artery occlusion, the level of collateral blood supply in the model and the neuroanatomical location of the region of interest (ROI) (e.g., ischemic core versus penumbra) with resulting differences in TSC.…”

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confidence: 99%

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Regional and temporal variations in tissue sodium concentration during the acute stroke phase

Wetterling

Gallagher

Macrae

et al. 2011

Magnetic Resonance in Med

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A technique for noninvasively quantifying the concentration of sodium (23Na) ions was applied to the study of ischemic stroke. 23Na‐magnetic resonance imaging techniques have shown considerable potential for measuring subtle changes in ischemic tissue, although studies to date have suffered primarily from poor signal/noise ratio. In this study, accurate quantification of tissue sodium concentration (TSC) was achieved in 23Na images with voxel sizes of 1.2 μL acquired in 10 min. The evolution of TSC was investigated from 0.5 to 8 h in focal cortical and subcortical ischemic tissue following permanent middle cerebral artery occlusion in the rat (n = 5). Infarct volumes determined from TSC measurements correlated significantly with histology (P = 0.0006). A delayed linear model was fitted to the TSC time course data in each voxel, which revealed that the TSC increase was more immediate (0.2 ± 0.1 h delay time) in subcortical ischemic tissue, whereas it was delayed by 1.6 ± 0.5 h in ischemic cortex (P = 0.0002). No significant differences (P = 0.5) were measured between TSC slope rates in cortical (10.2 ± 1.1 mM/h) and subcortical (9.7 ± 1.1 mM/h) ischemic tissue. The data suggest that any TSC increase measured in ischemic tissue indicates infarction (core) and regions exhibiting a delay to TSC increase indicate potentially salvageable tissue (penumbra). Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.

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Sodium MR Imaging of Acute and Subacute Stroke for Assessment of Tissue Viability

Cited by 104 publications

References 24 publications

The design of a double-tuned two-port surface resonator and its application to in vivo Hydrogen- and Sodium-MRI

The design of a double-tuned two-port surface resonator and its application to in vivo Hydrogen- and Sodium-MRI

Sodium MRI using a density‐adapted 3D radial acquisition technique

Regional and temporal variations in tissue sodium concentration during the acute stroke phase

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