Field strength and dose dependence of contrast enhancement by gadolinium-based MR contrast agents

Rinck, Peter A.; Müller, Robert N.

doi:10.1007/s003300050781

Cited by 120 publications

(71 citation statements)

References 25 publications

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“…Furthermore, it can be used flexibly to reduce acquisition time, improve spatial resolution, or both (24 -26). Also, since the longitudinal relaxation time (T1) of unenhanced blood increases with field strength, sensitivity to injected Gd agents is heightened (5). In addition, the background noise is reduced at 3.0T because of the shortening of T2*, result in better discrimination of vascular segments.…”

Section: Discussionmentioning

confidence: 99%

Dynamic pulmonary perfusion and flow quantification with MR imaging, 3.0T vs. 1.5T: Initial results

Nael

Michaely

Lee

et al. 2006

Magnetic Resonance Imaging

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Purpose: To prospectively evaluate the technical feasibility and relative performance of pulmonary time-resolved MR angiography (MRA) and pulmonary artery (PA) flow quantification at 3.0T vs. 1.5T. Materials and Methods:Time-resolved contrast-enhanced (CE) MRA of the pulmonary circulation, and flow quantification of the main PA (MPA) were performed in 14 consecutive adult healthy volunteers at both 1.5 and 3.0 Tesla with nearly identical sequence parameters. Image quality, signal-to-noise ratio (SNR), and quantitative indices of pulmonary perfusion, flow, and velocity were evaluated and compared at both field strengths.Results: Time-resolved pulmonary MRA, perfusion, and flow quantification were successfully performed at both magnetic fields. The results of pulmonary perfusion and flow indices were comparable at both magnetic fields, with no statistically significant difference. The SNR values for vascular structures were higher at 3.0T vs. 1.5T (P ϭ 0.001). The SNR values and the definition scores for parenchymal enhancement were significantly lower (P ϭ 0.008 and 0.001, respectively) at 3.0T. Conclusion:Time-resolved pulmonary MRA, perfusion, and flow quantification at 3.0T was feasible, with comparable results to 1.5T. The lower parenchymal enhancement at 3.0T is believed to reflect increased susceptibility effects at higher magnetic fields. Further work is needed to fully exploit the potential of pulmonary perfusion imaging at 3.0T and to address the current limitations.Key Words: pulmonary perfusion with MRI; time-resolved pulmonary MRA at 3.0T; pulmonary flow at 3.0T; comparison of 3.0T vs. MRI IS INCREASINGLY being applied to the study of pulmonary vascular anatomy, perfusion, and blood flow. Time-resolved contrast-enhanced magnetic resonance angiography (CE-MRA) in particular is well suited for studying the pulmonary circulation because it offers the potential for simultaneous evaluation of vascular anatomy and dynamic microvascular parenchymal enhancement.Recently, parallel imaging with k-space undersampling has improved the temporal and spatial resolution of time-resolved MRA (1,2) with positive results at 1.5T. Phase-sensitive velocity imaging has been successfully applied to the study of pulmonary artery (PA) blood flow for some time (3,4).With the advent of whole-body, 3.0T MR systems, the promise is that performance and image quality can be even further enhanced. The higher available signal-tonoise ratio (SNR) can be used to support fast imaging tools, improving both spatial and temporal resolution. Also, since the longitudinal relaxation time (T1) of unenhanced blood increases with field strength (5), sensitivity to injected gadolinium (Gd) agents for CE-MRA may be heightened. There are, however, substantial technical challenges presented by MRI at 3.0T. Specific absorption rates (SAR) set lower limits on nominal flip angles, and dielectric resonances and radiofrequency (RF) eddy currents may result in B 1 inhomogeneity, which can negatively impact image quality (6 -8). Magnetic susceptibility eff...

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Section: Discussionmentioning

confidence: 99%

Dynamic pulmonary perfusion and flow quantification with MR imaging, 3.0T vs. 1.5T: Initial results

Nael

Michaely

Lee

et al. 2006

Magnetic Resonance Imaging

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“…However, high doses may cause problems with toxicity and tolerance. 26 In a T 1 -weighted image, the signal intensity of the voxel will be inversely proportional to the T 1 of the water protons contained within that voxel. The observed relaxation time is the sum of the…”

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confidence: 99%

The Gadonanotubes as High-Performance MRI Contrast Agents: The Unappreciated Role of the Carbon Nanotube Component at Low Magnetic Fields

Moghaddam¹,

Sethi²,

Shayeganfar³

et al. 2017

ECS J. Solid State Sci. Technol.

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The Gadonanotubes (GNTs) are the highest-performing T 1 -weighted MRI contrast agent material known with a relaxivity of ∼160 mM −1 s −1 per Gd 3+ ion at 1.5 T. In this work, the contribution of carbon-based free radicals at defect sites on the sidewalls of the ultra-short carbon nanotube (US-tube) component of the GNTs to the T 1 relaxation time has been investigated by Nuclear Magnetic Resonance Dispersion (NMRD) and Electron Paramagnetic Resonance (EPR) studies. The NMRD results indicate that carbon-based radicals of the US-tube structure substantially shorten water proton spin-lattice relaxation times at low frequencies (< 1 MHz) and that the high water proton relaxation rate for the GNTs at these fields does not result from the Gd 3+ ion alone. Furthermore, a computational study suggests that the defect sites of the US-tube structure increase nanotube strain and create new interband electronic states. While the presence of Gd 3+ ions at the defect sites for the GNTs do not induce new electronic states, they do introduce a shift in the Fermi level to higher energy (0.4 eV).

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“…As field strength is lowered, de Graaf et al [38] have shown that T 1 decreases and T 2 increases in both rat brain white matter and gray matter. Rinck et al [39] have shown increasing relaxivities, R 1 and R 2 (decreased relaxation times T 1 and T 2 ), of gadolinium-based contrast agents with decreases in field strength. For different contrast agents, Rohrer et al [16] have also shown variations of relaxivities with decreases in field strength.…”

Section: Discussionmentioning

confidence: 99%

Quantitative assessment of macromolecular concentration during direct infusion into an agarose hydrogel phantom using contrast-enhanced MRI

Chen

Astary

Sepulveda

et al. 2008

Magnetic Resonance Imaging

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Convection-enhanced delivery (CED), i.e., direct tissue infusion, has emerged as a promising local drug delivery method for treating diseases of the nervous system. Determination of the spatial distribution of therapeutic agents after infusion is important in evaluating the efficacy of treatment, optimizing infusion protocols, and improving the understanding of drug pharmacokinetics. In this study, we provide a methodology to determine the concentration distribution of Gd-labeled tracers during infusion using contrast-enhanced MR imaging. To the best of our knowledge, MR studies that quantify concentration profiles for CED have not been previously reported. The methodology utilizes intrinsic material properties (T 1 and R 1 ) and reduces the effect of instrumental factors (e.g., inhomogeneity of MR detection field). As a methodology investigation, this study used an agarose hydrogel phantom as a tissue substitute for infusion. An 11.1 T magnet system was used to image infusion of Gd-DTPA labeled albumin (Gd-albumin) into the hydrogel. By using data from preliminary scans, Gd-albumin distribution was determined from the signal intensity of the MR images. As a validation test, MR-derived concentration profiles were found comparable to both results measured directly using quantitative optical imaging and results from a computational transport model in porous media. In future studies, the developed methodology will be used to quantitatively monitor the distribution of Gd-tracer following infusion directly into tissues.

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Field strength and dose dependence of contrast enhancement by gadolinium-based MR contrast agents

Cited by 120 publications

References 25 publications

Dynamic pulmonary perfusion and flow quantification with MR imaging, 3.0T vs. 1.5T: Initial results

Dynamic pulmonary perfusion and flow quantification with MR imaging, 3.0T vs. 1.5T: Initial results

The Gadonanotubes as High-Performance MRI Contrast Agents: The Unappreciated Role of the Carbon Nanotube Component at Low Magnetic Fields

Quantitative assessment of macromolecular concentration during direct infusion into an agarose hydrogel phantom using contrast-enhanced MRI

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