Monitoring of brain potassium with rubidium flame photometry and MRI

Yushmanov, Victor E.; Kharlamov, Alexander; Boada, Fernando E.; Jones, Stephen C.

doi:10.1002/mrm.21155

Cited by 16 publications

(32 citation statements)

References 40 publications

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“…T 1 and T 2 relaxation times are well suited to magnetic resonance imaging using specialized coils, and this approach has been used to quantitatively assess K (using 87 Rb as a proxy) in the brains of ischemic rats [42, 43]. This approach uses chronic Rb loading via drinking water in the weeks preceding MRI scanning, which could be employed in a diagnostic workflow for AD, though the use of high field strength (e.g., 7 T) MRI systems may have the capacity to assess endogenous 87 Rb with sufficient sensitivity.…”

Section: Discussionmentioning

confidence: 99%

Rubidium and potassium levels are altered in Alzheimer’s disease brain and blood but not in cerebrospinal fluid

Roberts

Doecke

Rembach

et al. 2016

acta neuropathol commun

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Loss of intracellular compartmentalization of potassium is a biochemical feature of Alzheimer’s disease indicating a loss of membrane integrity and mitochondrial dysfunction. We examined potassium and rubidium (a biological proxy for potassium) in brain tissue, blood fractions and cerebrospinal fluid from Alzheimer’s disease and healthy control subjects to investigate the diagnostic potential of these two metal ions. We found that both potassium and rubidium levels were significantly decreased across all intracellular compartments in the Alzheimer’s disease brain. Serum from over 1000 participants in the Australian Imaging, Biomarkers and Lifestyle Flagship Study of Ageing (AIBL), showed minor changes according to disease state. Potassium and rubidium levels in erythrocytes and cerebrospinal fluid were not significantly different according to disease state, and rubidium was slightly decreased in Alzheimer’s disease patients compared to healthy controls. Our data provides evidence that contrasts the hypothesized disruption of the blood-brain barrier in Alzheimer’s disease, with the systemic decrease in cortical potassium and rubidium levels suggesting influx of ions from the blood is minimal and that the observed changes are more likely indicative of an internal energy crisis within the brain. These findings may be the basis for potential diagnostic imaging studies using radioactive potassium and rubidium tracers.Electronic supplementary materialThe online version of this article (doi:10.1186/s40478-016-0390-8) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Rubidium and potassium levels are altered in Alzheimer’s disease brain and blood but not in cerebrospinal fluid

Roberts

Doecke

Rembach

et al. 2016

acta neuropathol commun

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“…In contrast to MR imaging, a substantial drawback of these methods is the lack of information on the spatial potassium distribution. An alternative approach to assess the potassium homeostasis is the partial replacement of K + by ionic rubidium (Rb + ), because rubidium 87 MR imaging yields an approximately 20-fold higher SNR (19) compared with the SNR of 39 K MR imaging. However, this approach cannot be implemented in humans.…”

Section: Brain Imagingmentioning

confidence: 99%

In Vivo³⁹K MR Imaging of Human Muscle and Brain

Umathum¹,

Rösler²,

Nagel³

2013

Radiology

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“…The 87 Rb NMR methods for inferential studies of K + in cardiac metabolism and injury were significantly refined, and 87 Rb MRI was originally developed and used for detection of changes of K + balance in cardiac ischemia in the model of isolated perfused pig heart (12). To monitor K + in the rat brain in vivo, K/Rb substitution MRI was recently introduced (13). Partial K replacement with Rb was shown not to interfere with ion dynamics in ischemic brain over time and can be detected by 87 Rb MRI in vivo with custom-built radiofrequency (RF) coils (13).…”

Section: Introductionmentioning

confidence: 99%

“…To monitor K + in the rat brain in vivo, K/Rb substitution MRI was recently introduced (13). Partial K replacement with Rb was shown not to interfere with ion dynamics in ischemic brain over time and can be detected by 87 Rb MRI in vivo with custom-built radiofrequency (RF) coils (13). MRI quantification of 87 Rb in the brain still poses a significant challenge, however, because of its very short T 2 (~0.35 ms (9)), natural abundance of only 28%, and, therefore, relatively low tissue concentration.…”

Section: Introductionmentioning

confidence: 99%

K⁺ dynamics in ischemic rat brain in vivo by ⁸⁷Rb MRI at 7 T

et al. 2011

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The aims of the present study were 1) to perform the first 87Rb MRI in live rats with a focal ischemic stroke; and 2) to test the hypothesis that K+ egress from the brain in this model is quantifiable in individual animals by the high field (7 T) K/Rb substitution MRI. Rats pre-loaded with dietary Rb+ (resulting in replacement ratios Rb/(K+Rb) of 0.1 to 0.2 in the brain) were subjected to permanent occlusion of the middle cerebral artery, and 87Rb MRI was implemented with 13-min temporal resolution using a dedicated radiofrequency coil and a spiral ultrashort-TE sequence (TR/TE of 3/0.07 ms). The ischemic core was localized by apparent diffusion coefficient mapping, by microtubule-associated protein-2 immunohistochemistry, and by changes in surface reflectivity. [K], [Na] and [Rb] were independently determined in the micropunched samples by post-mortem flame photometry. Both techniques were generally in agreement in the non-ischemic cortex, however, the MRI-assessed [K++Rb+] drop in ischemic brain was less pronounced (average efflux rate of 4.8 ± 0.2 nEq/mm3/h, vs. 10 ± 1 nEq/mm3/h by flame photometry, P < 0.0001). The use of higher field gradients for better spatial resolution and, hence, more accurate quantitation, is suggested.

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Monitoring of brain potassium with rubidium flame photometry and MRI

Cited by 16 publications

References 40 publications

Rubidium and potassium levels are altered in Alzheimer’s disease brain and blood but not in cerebrospinal fluid

Rubidium and potassium levels are altered in Alzheimer’s disease brain and blood but not in cerebrospinal fluid

In Vivo³⁹K MR Imaging of Human Muscle and Brain

K⁺ dynamics in ischemic rat brain in vivo by ⁸⁷Rb MRI at 7 T

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Monitoring of brain potassium with rubidium flame photometry and MRI

Cited by 16 publications

References 40 publications

Rubidium and potassium levels are altered in Alzheimer’s disease brain and blood but not in cerebrospinal fluid

Rubidium and potassium levels are altered in Alzheimer’s disease brain and blood but not in cerebrospinal fluid

In Vivo39K MR Imaging of Human Muscle and Brain

K+ dynamics in ischemic rat brain in vivo by 87Rb MRI at 7 T

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Product

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In Vivo³⁹K MR Imaging of Human Muscle and Brain

K⁺ dynamics in ischemic rat brain in vivo by ⁸⁷Rb MRI at 7 T