Abstract:
:Fe(III)meso-tetra(4-sulfonatophenyl)porphine (Fe-TPPS4) has been investigated as a potential pH-sensitive nuclear magnetic resonance (NMR) proton image contrast agent. Relaxation rates (1/T1 and 1/T2) of water protons were measured as a function of pH and concentration of Fe-TPPS4 in phosphate-buffered isotonic saline. Transverse relaxation rates (1/T2) did not change appreciably with pH above 6.0. Longitudinal relaxation rates (1/T1) increased significantly between pH 7.75 and 5.75. This effect was more pronounced with the increasing concentration of Fe-TPPS4 from 0.1 to 1.5 mM and is attributed to a pH-dependent equilibrium between the high-spin (S = 5/2) Fe-TPPS4 monomer at low pH and the antiferromagnetically coupled mu-oxodimer O-(FeTPPS4)2 at high pH. The efficacy of this pH-dependent contrast agent is demonstrated in vitro.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Helpern JA,Curtis JC,Hearshen D,Smith MB,Welch KMdoi
10.1002/mrm.1910050313subject
Has Abstractpub_date
1987-09-01 00:00:00pages
302-5issue
3eissn
0740-3194issn
1522-2594journal_volume
5pub_type
杂志文章abstract::In several applications, MRI is used to monitor the time behavior of the signal in an organ of interest; e.g., signal evolution because of physiological motion, activation, or contrast-agent accumulation. Dynamic applications involve acquiring data in a k-t space, which contains both temporal and spatial information. ...
journal_title:Magnetic resonance in medicine
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journal_title:Magnetic resonance in medicine
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更新日期:1996-01-01 00:00:00
abstract::The purpose of the study was to test a newly developed, MR-compatible, liquid nitrogen-cooled cryoprobe. The probe has an outer diameter of 3.5 mm and was specifically developed for percutaneous, MR-guided, interstitial cryotherapy. The probe was inserted percutaneously into the livers of 10 rabbits. The cryotherapy p...
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更新日期:1998-03-01 00:00:00
abstract::Chemical exchange saturation transfer (CEST), arterial spin labeling (ASL), and magnetization transfer contrast (MTC) methods generate different contrasts for MRI. However, they share many similarities in terms of pulse sequences and mechanistic principles. They all use RF pulse preparation schemes to label the longit...
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更新日期:2018-10-01 00:00:00
abstract::The intra-individual and inter-individual variations of the global N-acetylaspartate (NAA) concentration were measured in a cohort of five 42+/-5 year-old normal females. The total NAA signal from the whole head was obtained with non-localized non-echo proton spectroscopy (1H-MRS) and converted into absolute mole amou...
journal_title:Magnetic resonance in medicine
pub_type: 临床试验,杂志文章
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更新日期:1998-11-01 00:00:00
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更新日期:2011-01-01 00:00:00
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更新日期:2011-01-01 00:00:00
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更新日期:2019-12-01 00:00:00