Dataset Information

Relaxation measurements of an MRI system phantom at low magnetic field strengths.

ABSTRACT:

Objective

Temperature controlled T₁ and T₂ relaxation times are measured on NiCl₂ and MnCl₂ solutions from the ISMRM/NIST system phantom at low magnetic field strengths of 6.5 mT, 64 mT and 550 mT.

Materials and methods

The T₁ and T₂ were measured of five samples with increasing concentrations of NiCl₂ and five samples with increasing concentrations of MnCl₂. All samples were scanned at 6.5 mT, 64 mT and 550 mT, at sample temperatures ranging from 10 °C to 37 °C.

Results

The NiCl₂ solutions showed little change in T₁ and T₂ with magnetic field strength, and both relaxation times decreased with increasing temperature. The MnCl₂ solutions showed an increase in T₁ and a decrease in T₂ with increasing magnetic field strength, and both T₁ and T₂ increased with increasing temperature.

Discussion

The low field relaxation rates of the NiCl₂ and MnCl₂ arrays in the ISMRM/NIST system phantom are investigated and compared to results from clinical field strengths of 1.5 T and 3.0 T. The measurements can be used as a benchmark for MRI system functionality and stability, especially when MRI systems are taken out of the radiology suite or laboratory and into less traditional environments.

SUBMITTER: Martin MN

PROVIDER: S-EPMC10386925 | biostudies-literature | 2023 Jul

REPOSITORIES: biostudies-literature

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Publications

Relaxation measurements of an MRI system phantom at low magnetic field strengths.

Martin Michele N MN Jordanova Kalina V KV Kos Anthony B AB Russek Stephen E SE Keenan Kathryn E KE Stupic Karl F KF

Magma (New York, N.Y.) 20230520 3

<h4>Objective</h4>Temperature controlled T<sub>1</sub> and T<sub>2</sub> relaxation times are measured on NiCl<sub>2</sub> and MnCl<sub>2</sub> solutions from the ISMRM/NIST system phantom at low magnetic field strengths of 6.5 mT, 64 mT and 550 mT.<h4>Materials and methods</h4>The T<sub>1</sub> and T<sub>2</sub> were measured of five samples with increasing concentrations of NiCl<sub>2</sub> and five samples with increasing concentrations of MnCl<sub>2</sub>. All samples were scanned at 6.5 mT, ...[more]

PMID: 37209233

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Project description:The key criteria to optimize the relaxivity of a Gd(III) contrast agent at high fields (defined as the region ≥ 1.5 T) can be summarized as follows: (i) the occurrence of a rotational correlation time τR in the range of ca. 0.2-0.5 ns; (ii) the rate of water exchange is not critical, but a τM < 100 ns is preferred; (iii) a relevant contribution from water molecules in the second sphere of hydration. In addition, the use of macrocycle-based systems ensures the formation of thermodynamically and kinetically stable Gd(III) complexes. Binuclear Gd(III) complexes could potentially meet these requirements. Their efficiency depends primarily on the degree of flexibility of the linker connecting the two monomeric units, the absence of local motions and the presence of contribution from the second sphere water molecules. With the aim to maximize relaxivity (per Gd) over a wide range of magnetic field strengths, two binuclear Gd(III) chelates derived from the well-known macrocyclic systems DOTA-monopropionamide and HPDO3A (Gd2L1 and Gd2L2, respectively) were synthesized through a multistep synthesis. Chemical Exchange Saturation Transfer (CEST) experiments carried out on Eu2L2 at different pH showed the occurrence of a CEST effect at acidic pH that disappears at neutral pH, associated with the deprotonation of the hydroxyl groups. Then, a complete 1H and 17O NMR relaxometric study was carried out in order to evaluate the parameters that govern the relaxivity associated with these complexes. The relaxivities of Gd2L1 and Gd2L2 (20 MHz, 298 K) are 8.7 and 9.5 mM-1 s-1, respectively, +77% and +106% higher than the relaxivity values of the corresponding mononuclear GdDOTAMAP-En and GdHPDO3A complexes. A significant contribution of second sphere water molecules was accounted for the strong relaxivity enhancement of Gd2L2. MR phantom images of the dinuclear complexes compared to GdHPDO3A, recorded at 7 T, confirmed the superiority of Gd2L2. Finally, ab initio (DFT) calculations were performed to obtain information about the solution structure of the dinuclear complexes.

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Dataset Information

Relaxation measurements of an MRI system phantom at low magnetic field strengths.

Objective

Materials and methods

Results

Discussion

Publications

Relaxation measurements of an MRI system phantom at low magnetic field strengths.

Similar Datasets

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