Magnetic field dependence of solvent proton relaxation induced by Gd<sup>3+</sup> and Mn<sup>2+</sup> complexes

Koenig, Seymour H.; Baglin, Coral M.; Brown, Rodney D.; Brewer, C. Fred

doi:10.1002/mrm.1910010408

Cited by 111 publications

(74 citation statements)

References 15 publications

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“…This effect is even more noticeable in phosphonate complexes with no inner-sphere water, such as Gd(DOTMP) [26]. This observation was in agreement with the X-ray crystal structure of the same complex [27] and further confirmed by proton nuclear magnetic relaxation dispersion studies [28]. The same technique was applied to MnL 1 , giving a value of q = 1.20; this was corrected to q = 1.32 or 1.44 assuming one or two unbound phosphonate groups at a time [26].…”

Section: Proton Relaxivitiessupporting

confidence: 86%

Hydroxy double salts intercalated with Mn(II) complexes as potential contrast agents

Jin

Spillane

et al. 2016

Solid State Sciences

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Section: Proton Relaxivitiessupporting

confidence: 86%

Hydroxy double salts intercalated with Mn(II) complexes as potential contrast agents

Jin

Spillane

et al. 2016

Solid State Sciences

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“…[1]- [5], is reenforced by the values derived for the parameters of the theory; it is unequivocal that the parameters of the Mn3+(TPPS4) complex, and none of the other complexes, are anomalous.…”

Section: Discussionmentioning

confidence: 99%

The anomalous relaxivity of Mn³⁺(TPPS₄)

Koenig

Brown

Spiller

1987

Magnetic Resonance in Med

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105

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It was recently reported (C-W. Chen et al., FEBS Lett. 168, 70 (1984)) that water solutions of Mn3+ (TPPS4) have a surprisingly high relaxivity at 20 MHz and 37 degrees C, greater than most Mn2+ complexes including the hexaaquoion. Because Mn3+ (TPPS4) is highly stable, and porphyrins in general are tumor-seeking, we have sought to understand the origin of the large relaxivity by comparing the 1/T1 NMRD profiles (magnetic field dependence of 1/T1 of solvent protons) of Mn3+ (TPPS4) solutions with those of a number of other small Fe3+ and Mn2+ complexes. By relating the measured NMRD profiles to the theory of relaxation by magnetic dipolar interactions, in a form appropriate for small paramagnetic solute molecules, we establish that the theory affords an excellent quantitative description of the relaxation behavior of all the samples, and confirm that the relaxivity of Mn3+ (TPPS4) is anomalously high. The effect is attributed, in part, to the anisotropy of the ground-state wavefunction of Mn3+ in the porphyrin complex, effectively bringing the spin density of the Mn3+ ions closer to the protons of the coordinated water molecules than would a spherically symmetric S-state ion. In addition, the paramagnetic relaxation time of the Mn3+ spins, though short, is longer than would be anticipated for a non-S-state ion, and increases substantially with magnetic field above about 2 MHz. In this regard, Mn3+ (TPPS4) may be one of a class of molecules with properties particularly favorable for use as contrast-enhancing agents in magnetic resonance imaging.

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“…The 1 H longitudinal relaxation rate of Gd-DTPA solution (1/T 1 ) is the sum of the intrinsic relaxation rate of CSF (1/T csf ) and the relaxivity of the Gd-DTPA (R gd ), which is proportional to the Gd-DTPA concentration ([Gd]), and the relaxivity value of the Gd-DTPA (K 1 ) [19]. 1/T 1 is given by…”

Section: Methodsmentioning

confidence: 99%

Effects of pCO2 on the CSF Turnover Rate in Rats Monitored by Gd-DTPA Enhanced T1-Weighted Magnetic Resonance Imaging.

Takamata

Seo²,

Ogino³

et al. 2001

JJP

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Hypercapnia produces a vasodilatation of the cerebral vasculature with an increase in cerebral blood flow and hypocapnia causes vasoconstriction with a decrease in cerebral blood flow. The cerebrospinal fluid (CSF) pressure was increased by hypercapnia and decreased by hypocapnia [1]. This suggested that the formation of CSF might be altered by carbon dioxide. However, we have seen conflicting results in regard to the influence of hypercapnia and hypocapnia on CSF formation [2][3][4][5][6]. To confirm the effects of CO 2 , we developed a new method to measure local CSF turnover rate in the lateral ventricle of the rat brain.Several methods have been developed to measure the rate of CSF production, based on (i) drainage of CSF from the cisterna magna or aqueduct; (ii) clearance of injected substances, such as inulin or dextran; and (iii) ventriculocisternal perfusion. The drainage technique was the earliest, and it was a direct attempt to measure the CSF production rate [7]. This method was applied in experiments using large animals such as dogs and cats, but it is not suitable for small animals such as rats and mice. The ventriculocisternal perfusion method [8] employs an inflow-cannula, inserted into a lateral ventricle, and an outflow-cannula in the cisterna magna. An artificial CSF is pumped in Key words: 1 H MRI, production of cerebrospinal fluid, hypocapnia, hypercapnia, carbonic anhydrase inhibitor. Abstract:The cerebrospinal fluid (CSF) secretion of rat was monitored by longitudinal relaxation time-weighted magnetic resonance imaging (T 1 -weighted MRI) in combination with a ventricular injection of a T 1 -relaxation reagent: gadolinium-diethylene triamine-N,N,NЈ,NЉ,NЉ-pentaacetic acid (Gd-DTPA). A cannula was inserted in the left lateral ventricle, and 5 l of 8.5 mM Gd-DTPA was injected as a CSF marker. Changes in the image intensity of the CSF were measured every 30 s, and the turnover rate of CSF (k) in the left lateral ventricle was obtained from the dilution of Gd-DTPA, based on the assumption of a single compartment model. In the control conditions, k was 0.158Ϯ0.009 min Ϫ1 at an arterial blood CO 2 tension (pCO 2 ) of 38.6Ϯ2.2 mmHg (nϭ10), which corresponds to the CSF secretion rate of 3.6 l min Ϫ1. The k value was decreased (0.078Ϯ0.010 min Ϫ1, nϭ4) by a carbonic-anhydrase inhibitor (acetazolamide). The turnover rate was decreased by hypocapnia (0.094Ϯ0.019 min Ϫ1, pCO 2 ϭ24.7Ϯ 2.9 mmHg, nϭ4), and it increased gradually and reached a plateau level as a result of hypercapnia (0.194Ϯ0.011 min Ϫ1, pCO 2 ϭ104.5Ϯ7.1 mmHg, nϭ10). These results suggested that CO 2 upregulates the secretion of CSF in the rat.

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Magnetic field dependence of solvent proton relaxation induced by Gd³⁺ and Mn²⁺ complexes

Cited by 111 publications

References 15 publications

Hydroxy double salts intercalated with Mn(II) complexes as potential contrast agents

Hydroxy double salts intercalated with Mn(II) complexes as potential contrast agents

The anomalous relaxivity of Mn³⁺(TPPS₄)

Effects of pCO2 on the CSF Turnover Rate in Rats Monitored by Gd-DTPA Enhanced T1-Weighted Magnetic Resonance Imaging.

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Magnetic field dependence of solvent proton relaxation induced by Gd3+ and Mn2+ complexes

Cited by 111 publications

References 15 publications

Hydroxy double salts intercalated with Mn(II) complexes as potential contrast agents

Hydroxy double salts intercalated with Mn(II) complexes as potential contrast agents

The anomalous relaxivity of Mn3+(TPPS4)

Effects of pCO2 on the CSF Turnover Rate in Rats Monitored by Gd-DTPA Enhanced T1-Weighted Magnetic Resonance Imaging.

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Magnetic field dependence of solvent proton relaxation induced by Gd³⁺ and Mn²⁺ complexes

The anomalous relaxivity of Mn³⁺(TPPS₄)