scholarly journals On restoring motion-induced signal loss in single-voxel magnetic resonance spectra

2006 ◽  
Vol 56 (4) ◽  
pp. 754-760 ◽  
Author(s):  
Refaat E. Gabr ◽  
Shashank Sathyanarayana ◽  
Michael Schär ◽  
Robert G. Weiss ◽  
Paul A. Bottomley
Keyword(s):  
Magnetic Resonance ◽  
Signal Loss ◽  
Single Voxel ◽  
Induced Signal ◽  
Magnetic Resonance Spectra

scholarly journals in Vivo Monitoring of Macrophage Infiltration in Experimental Ischemic Brain Lesions by Magnetic Resonance Imaging

2003 ◽  
Vol 23 (11) ◽  
pp. 1356-1361 ◽  
Author(s):  
Christoph Kleinschnitz ◽  
Martin Bendszus ◽  
Marco Frank ◽  
Laszlo Solymosi ◽  
Klaus V Toyka ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Brain Lesions ◽  
Macrophage Infiltration ◽  
Signal Loss ◽  
Resonance Imaging ◽  
Ischemic Brain ◽  
Induced Signal ◽  
Local Accumulation

Although macrophages represent the major inflammatory cells in cerebral ischemia, the kinetics of macrophage infiltration are largely unknown. To address this issue, we injected superparamagnetic iron oxide (SPIO) particles into the circulation of rats at different time points after focal photothrombotic cerebral infarction and performed magnetic resonance imaging (MRI) 24 hours later. Infarcts appeared as hyperintense lesions on T2-w and CISS MR images during all stages. At days 5.5 and 6, an additional rim of signal loss indicative of local accumulation of SPIO particles appeared at the outer margin of the hyperintense ischemic lesions, which was not present at days 1 to 5. Areas of signal loss corresponded to local accumulation of iron-loaded macrophages in histologic sections. At day 8, signal loss became restricted to the inner core of the lesions and ceased thereafter. Macrophages, however, were still present in late ischemic brain lesions, but they were iron-negative. Thus SPIO-induced signal loss indicates active macrophage transmigration into ischemic infarcts but not their mere presence. SPIO-induced signal loss was independent from the disturbance of the blood-brain barrier. In conclusion, we have shown by in vivo monitoring that macrophages enter photothrombotic infarcts at late stages of infarct development, suggesting a role in tissue remodeling rather than neuronal injury.

scholarly journals Robust Conditional Independence maps of single-voxel Magnetic Resonance Spectra to elucidate associations between brain tumours and metabolites

PLoS ONE ◽  
2020 ◽  
Vol 15 (7) ◽  
pp. e0235057
Author(s):  
Raúl Vicente Casaña-Eslava ◽  
Sandra Ortega-Martorell ◽  
Paulo J. Lisboa ◽  
Ana Paula Candiota ◽  
Margarida Julià-Sapé ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Brain Tumours ◽  
Conditional Independence ◽  
Single Voxel ◽  
Magnetic Resonance Spectra

The preparation of 2-Fluoro-5-nitrobenzonitrile and the proton magnetic resonance spectra of some compounds containing the N-(2-Cyano-4-nitrophenyl) group

1967 ◽  
Vol 20 (8) ◽  
pp. 1663 ◽  
Author(s):  
JFK Wilshire
Keyword(s):  
Amino Acids ◽  
Magnetic Resonance ◽  
Nitro Group ◽  
Proton Magnetic Resonance ◽  
Cyano Group ◽  
Aromatic Nucleus ◽  
Heteroaromatic Compounds ◽  
Magnetic Resonance Spectra

2-Fluoro-5-nitrobenzonitrile, an analogue of 1-fluoro-2,4- dinitrobenzene, in which the 2-nitro group has been replaced by a cyano group, has been prepared and made to react with several amines, amino acids, and NH-heteroaromatic compounds. The proton magnetic resonance spectra of some of the resultant N-(2-cyano-4-nitrophenyl) derivatives were compared with the spectra of the corresponding N-(2,4- dinitrophenyl) derivatives and furnish further evidence that the ortho nitro group of the latter derivatives is rotated out of the plane of the aromatic nucleus.

Comparison of metal artifact reduction techniques in magnetic resonance imaging of carbon-reinforced PEEK and titanium spinal implants

2021 ◽  
pp. 028418512110290
Author(s):  
Georg Osterhoff ◽  
Florian A Huber ◽  
Laura C Graf ◽  
Ferdinand Erdlen ◽  
Hans-Christoph Pape ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Pedicle Screws ◽  
Artifact Reduction ◽  
Metal Artifact ◽  
Metal Artifact Reduction ◽  
Signal Loss ◽  
Resonance Imaging ◽  
Spinal Implants ◽  
Titanium Screws

Background Carbon-reinforced PEEK (C-FRP) implants are non-magnetic and have increasingly been used for the fixation of spinal instabilities. Purpose To compare the effect of different metal artifact reduction (MAR) techniques in magnetic resonance imaging (MRI) on titanium and C-FRP spinal implants. Material and Methods Rod-pedicle screw constructs were mounted on ovine cadaver spine specimens and instrumented with either eight titanium pedicle screws or pedicle screws made of C-FRP and marked with an ultrathin titanium shell. MR scans were performed of each configuration on a 3-T scanner. MR sequences included transaxial conventional T1-weighted turbo spin echo (TSE) sequences, T2-weighted TSE, and short-tau inversion recovery (STIR) sequences and two different MAR-techniques: high-bandwidth (HB) and view-angle-tilting (VAT) with slice encoding for metal artifact correction (SEMAC). Metal artifact degree was assessed by qualitative and quantitative measures. Results There was a much stronger effect on artifact reduction with using C-FRP implants compared to using specific MRI MAR-techniques (screw shank: P < 0.001; screw tulip: P < 0.001; rod: P < 0.001). VAT-SEMAC sequences were able to reduce screw-related signal loss artifacts in constructs with titanium screws to a certain degree. Constructs with C-FRP screws showed less artifact-related implant diameter amplification when compared to constructs with titanium screws ( P < 0.001). Conclusion Constructs with C-FRP screws are associated with significantly less artifacts compared to constructs with titanium screws including dedicated MAR techniques. Artifact-reducing sequences are able to reduce implant-related artifacts. This effect is stronger in constructs with titanium screws than in constructs with C-FRP screws.

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