scholarly journals Sodium-23 Magnetic Resonance Imaging Has Potential for Improving Penumbra Detection but Not for Estimating Stroke Onset Time

2014 ◽  
Vol 35 (1) ◽  
pp. 103-110 ◽  
Author(s):  
Friedrich Wetterling ◽  
Lindsay Gallagher ◽  
Jim Mullin ◽  
William M Holmes ◽  
Chris McCabe ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Onset Time ◽  
Sodium Concentration ◽  
Artery Occlusion ◽  
Stroke Onset ◽  
Resonance Imaging ◽  
Sodium Mri ◽  
The Core ◽  
Tissue Sodium

Tissue sodium concentration increases in irreversibly damaged (core) tissue following ischemic stroke and can potentially help to differentiate the core from the adjacent hypoperfused but viable penumbra. To test this, multinuclear hydrogen-1/sodium-23 magnetic resonance imaging (MRI) was used to measure the changing sodium signal and hydrogen-apparent diffusion coefficient (ADC) in the ischemic core and penumbra after rat middle cerebral artery occlusion (MCAO). Penumbra and core were defined from perfusion imaging and histologically defined irreversibly damaged tissue. The sodium signal in the core increased linearly with time, whereas the ADC rapidly decreased by >30% within 20 minutes of stroke onset, with very little change thereafter (0.5–6 hours after MCAO). Previous reports suggest that the time point at which tissue sodium signal starts to rise above normal (onset of elevated tissue sodium, OETS) represents stroke onset time (SOT). However, extrapolating core data back in time resulted in a delay of 72±24 minutes in OETS compared with actual SOT. At the OETS in the core, penumbra sodium signal was significantly decreased (88±6%, P=0.0008), whereas penumbra ADC was not significantly different (92±18%, P=0.2) from contralateral tissue. In conclusion, reduced sodium-MRI signal may serve as a viability marker for penumbra detection and can complement hydrogen ADC and perfusion MRI in the time-independent assessment of tissue fate in acute stroke patients.

Influence of Gadolinium-Based Contrast Agents on Tissue Sodium Quantification in Sodium Magnetic Resonance Imaging

2018 ◽  
Vol 53 (9) ◽  
pp. 555-562 ◽  
Author(s):  
Nadia Karina Paschke ◽  
Wiebke Neumann ◽  
Tanja Uhrig ◽  
Manuel Winkler ◽  
Eva Neumaier-Probst ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Contrast Agents ◽  
Resonance Imaging ◽  
Tissue Sodium

scholarly journals Magnetic Resonance Imaging of Methane Hydrate Formation and Dissociation in Sandstone with Dual Water Saturation

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3231
Author(s):  
Stian Almenningen ◽  
Per Fotland ◽  
Geir Ersland
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Methane Hydrate ◽  
Water Saturation ◽  
High Water ◽  
Growth Patterns ◽  
Resonance Imaging ◽  
Initial Water ◽  
Hydrate Dissociation ◽  
The Core

This paper reports formation and dissociation patterns of methane hydrate in sandstone. Magnetic resonance imaging spatially resolved hydrate growth patterns and liberation of water during dissociation. A stacked core set-up using Bentheim sandstone with dual water saturation was designed to investigate the effect of initial water saturation on hydrate phase transitions. The growth of methane hydrate (P = 8.3 MPa, T = 1–3 °C) was more prominent in high water saturation regions and resulted in a heterogeneous hydrate saturation controlled by the initial water distribution. The change in transverse relaxation time constant, T2, was spatially mapped during growth and showed different response depending on the initial water saturation. T2 decreased significantly during growth in high water saturation regions and remained unchanged during growth in low water saturation regions. Pressure depletion from one end of the core induced a hydrate dissociation front starting at the depletion side and moving through the core as production continued. The final saturation of water after hydrate dissociation was more uniform than the initial water saturation, demonstrating the significant redistribution of water that will take place during methane gas production from a hydrate reservoir.

scholarly journals Spectacular Shrinking Deficit: Insights from Multimodal Magnetic Resonance Imaging after Embolic Middle Cerebral Artery Occlusion in Sprague—Dawley Rats

2007 ◽  
Vol 27 (10) ◽  
pp. 1756-1763 ◽  
Author(s):  
Nils Henninger ◽  
Kenneth M Sicard ◽  
Marc Fisher
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Middle Cerebral Artery ◽  
Artery Occlusion ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Cerebral Artery Occlusion

Almost no data is available on the serial changes in the brain after spectacular shrinking deficit (SSD) that may help understand this relatively rare clinical phenomenon. Quantitative diffusion-(DWI), perfusion-(PWI), T1-(T1WI), T2-weighted (T2WI), and functional magnetic resonance imaging (fMRI) were performed before, during, and up to 7 days after embolic middle cerebral artery occlusion (eMCAO) in male Sprague—Dawley rats ( n = 9). Region of interest (ROI) analysis was used to evaluate structural and functional MR signal changes within three ROIs defined by the apparent diffusion coefficient (ADC), cerebral blood flow (CBF) signatures, and final tissue viability. DWI, PWI, and T2WI lesion volumes were calculated using previously established viability thresholds and final infarct volumes ascertained with 2,3,5-triphenyltetrazolium chloride (TTC) staining. Serial MRI demonstrated spontaneous reperfusion of initially hypoperfused MCA regions accompanied by substantial reduction of initial ADC and CBF lesions and gradual recovery of neurological outcome. Recovery rates of CBF/ADC abnormalities differed among ROIs. Functional magnetic resonance imaging showed persistent tissue dysfunction after the recovery of the CBF/ADC lesions. This study may facilitate our understanding of the pathophysiological mechanisms by which early, spontaneous reperfusion affects tissue fate and neurological function.

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