THE PARAMAGNETIC PILLARED BENTONITES AS DIGESTIVE TRACT MRI CONTRAST AGENTS

The increased use of imaging techniques in diagnostic studies, such as MRI, has contributed to the development of the wide range of new materials which could be successfully used as image improving agents. However, there is a lack of such substances in the area of gastrointestinal tract MRI. Many of the traditionally popular relaxation altering agents show poor results and disadvantages provoking black bowel, side effects of diarrhea and the presence of artifacts arising from clumping. Paramagnetic species seem to be potentially suitable agents for these studies, but contrast opacification has been reported and less than 60% of the gastrointestinal tract magnetic resonance scans showed improved delineation of abdominal pathologies. The new solution has been proposed as zeolites or smectite clays (hectorite and montmorillonite) enclosing of paramagnetic metal ions obtained by ion-exchange methods. However, such materials have problems of leakage of paramagnetic ions causing the appearance of the various side-effects. In this study we show that Co +2 and Dy +3 paramagnetic-pillared bentonites could be successfully used as MRI digestive tract non-leaching contrast agents, altering the longitudinal and transverse relaxation times of fluids in contact with the clay minerals.

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Imaging Tissue Physiology In Vivo by Use of Metal Ion-Responsive MRI Contrast Agents

Pharmaceuticals ◽

10.3390/ph13100268 ◽

2020 ◽

Vol 13 (10) ◽

pp. 268 ◽

Cited By ~ 1

Author(s):

Pooyan Khalighinejad ◽

Daniel Parrott ◽

A. Dean Sherry

Keyword(s):

Contrast Agents ◽

Metal Ion ◽

Relaxation Times ◽

Essential Element ◽

Mri Contrast Agents ◽

Mri Contrast ◽

Mr Contrast Agents ◽

Wide Range ◽

Paramagnetic Metal

Paramagnetic metal ion complexes, mostly based on gadolinium (Gd3+), have been used for over 30 years as magnetic resonance imaging (MRI) contrast agents. Gd3+-based contrast agents have a strong influence on T1 relaxation times and are consequently the most commonly used agents in both the clinical and research environments. Zinc is an essential element involved with over 3000 different cellular proteins, and disturbances in tissue levels of zinc have been linked to a wide range of pathologies, including Alzheimer’s disease, prostate cancer, and diabetes mellitus. MR contrast agents that respond to the presence of Zn2+ in vivo offer the possibility of imaging changes in Zn2+ levels in real-time with the superior spatial resolution offered by MRI. Such responsive agents, often referred to as smart agents, are typically composed of a paramagnetic metal ion with a ligand encapsulating it and one or more chelating units that selectively bind with the analyte of interest. Translation of these agents into clinical radiology is the next goal. In this review, we discuss Gd3+-based MR contrast agents that respond to a change in local Zn2+ concentration.

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Paramagnetic pillared bentonites — The new digestive tract MRI contrast agents

Applied Clay Science ◽

10.1016/j.clay.2009.11.041 ◽

2010 ◽

Vol 48 (1-2) ◽

pp. 191-194 ◽

Cited By ~ 1

Author(s):

Miloš Mojović ◽

Marko Daković ◽

Predrag Banković ◽

Zorica Mojović

Keyword(s):

Contrast Agents ◽

Digestive Tract ◽

Mri Contrast Agents ◽

Mri Contrast

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The Application Of Molecular Sieves As Magnetic Resonance Imaging Contrast Agents

MRS Proceedings ◽

10.1557/proc-233-225 ◽

1991 ◽

Vol 233 ◽

Cited By ~ 6

Author(s):

Kenneth J. Balkus ◽

Iwona Bresinska ◽

Stanislaw Kowalak ◽

Stuart W. Young

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Contrast Agents ◽

Molecular Sieves ◽

Mri Contrast Agents ◽

Paramagnetic Species ◽

Resonance Imaging ◽

Mri Contrast ◽

Magnetic Resonance Imaging Contrast ◽

Magnetic Resonance Imaging Mri

ABSTRACTThe application of zeolite molecular sieves as Magnetic Resonance Imaging (MRI) contrast agents is presented. Recent progress is described for X, Y and A type zeolites modified with paramagnetic species.

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Gd/Y Hydroxide Nanosheets as Highly Efficient T1/T2 MRI Contrast Agents

Nanomaterials ◽

10.3390/nano11010017 ◽

2020 ◽

Vol 11 (1) ◽

pp. 17

Author(s):

Xin Li ◽

Zhenhai Xue ◽

Jinfeng Xia ◽

Guohong Zhou ◽

Danyu Jiang ◽

...

Keyword(s):

Contrast Agents ◽

Relaxation Times ◽

Mri Contrast Agents ◽

Mri Contrast ◽

Force Microscopy ◽

Highly Efficient ◽

Transmission Electron ◽

Magnetic Resonance Imaging Mri ◽

Cytotoxicity Assessment ◽

T2 Mri

To develop highly efficient T1/T2 magnetic resonance imaging (MRI) contrast agents (CAs), Gd/Y hydroxide nanosheets were synthesized by a simple exfoliation method from layer compounds using sodium polyacrylate (PAA) as a dispersant and stabilizer. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) results revealed the excellent performance of monolayer nanosheets with thicknesses of up to 1.5 nm. The MRI results of the T1 and T2 relaxation times showed that all of the Gd/Y hydroxide nanosheets have high longitudinal and transverse relaxivities (r1 and r2). In particular, the 10% Gd-LRH nanosheets exhibited excellent MRI performance (r1 = 103 mM−1 s−1, r2 = 372 mM−1 s−1), which is rarely reported. Based on the relationship between the structure of 10% Gd-LRH nanosheets and their MRI performances, and the highly efficient MRI of spaced Gd atoms in the nanosheets, a special model to explain the outstanding MRI performance of the 10% Gd-LRH nanosheets is suggested. The cytotoxicity assessment of the 10% Gd-LRH nanosheets, evaluated by CCK-8 assays on HeLa cells, indicated no significant cytotoxicity. This study presents a significant advancement in 2D nanomaterial MRI CA research, with Gd-doped nanosheets positioned as highly efficient T1/T2 MRI CA candidates.

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Functionalized Lanthanide Oxide Nanoparticles for Tumor Targeting, Medical Imaging, and Therapy

Pharmaceutics ◽

10.3390/pharmaceutics13111890 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1890

Author(s):

Mohammad Yaseen Ahmad ◽

Huan Yue ◽

Tirusew Tegafaw ◽

Shuwen Liu ◽

Son Long Ho ◽

...

Keyword(s):

Medical Imaging ◽

Contrast Agents ◽

Tumor Targeting ◽

Imaging Techniques ◽

Tumor Therapy ◽

Mri Contrast Agents ◽

Mri Contrast ◽

Lanthanide Oxide ◽

X Ray

Recent progress in functionalized lanthanide oxide (Ln2O3) nanoparticles for tumor targeting, medical imaging, and therapy is reviewed. Among the medical imaging techniques, magnetic resonance imaging (MRI) is an important noninvasive imaging tool for tumor diagnosis due to its high spatial resolution and excellent imaging contrast, especially when contrast agents are used. However, commercially available low-molecular-weight MRI contrast agents exhibit several shortcomings, such as nonspecificity for the tissue of interest and rapid excretion in vivo. Recently, nanoparticle-based MRI contrast agents have become a hot research topic in biomedical imaging due to their high performance, easy surface functionalization, and low toxicity. Among them, functionalized Ln2O3 nanoparticles are applicable as MRI contrast agents for tumor-targeting and nontumor-targeting imaging and image-guided tumor therapy. Primarily, Gd2O3 nanoparticles have been intensively investigated as tumor-targeting T1 MRI contrast agents. T2 MRI is also possible due to the appreciable paramagnetic moments of Ln2O3 nanoparticles (Ln = Dy, Ho, and Tb) at room temperature arising from the nonzero orbital motion of 4f electrons. In addition, Ln2O3 nanoparticles are eligible as X-ray computed tomography contrast agents because of their high X-ray attenuation power. Since nanoparticle toxicity is of great concern, recent toxicity studies on Ln2O3 nanoparticles are also discussed.

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Exceedingly small iron oxide nanoparticles as positive MRI contrast agents

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1620145114 ◽

2017 ◽

Vol 114 (9) ◽

pp. 2325-2330 ◽

Cited By ~ 172

Author(s):

He Wei ◽

Oliver T. Bruns ◽

Michael G. Kaul ◽

Eric C. Hansen ◽

Mariya Barch ◽

...

Keyword(s):

Iron Oxide ◽

Magnetic Resonance ◽

Contrast Agents ◽

Iron Oxide Nanoparticles ◽

Superparamagnetic Iron Oxide ◽

Mri Contrast Agents ◽

Oxide Nanoparticles ◽

Mri Contrast ◽

Wide Range ◽

Magnetic Resonance Imaging Mri

Medical imaging is routine in the diagnosis and staging of a wide range of medical conditions. In particular, magnetic resonance imaging (MRI) is critical for visualizing soft tissue and organs, with over 60 million MRI procedures performed each year worldwide. About one-third of these procedures are contrast-enhanced MRI, and gadolinium-based contrast agents (GBCAs) are the mainstream MRI contrast agents used in the clinic. GBCAs have shown efficacy and are safe to use with most patients; however, some GBCAs have a small risk of adverse effects, including nephrogenic systemic fibrosis (NSF), the untreatable condition recently linked to gadolinium (Gd) exposure during MRI with contrast. In addition, Gd deposition in the human brain has been reported following contrast, and this is now under investigation by the US Food and Drug Administration (FDA). To address a perceived need for a Gd-free contrast agent with pharmacokinetic and imaging properties comparable to GBCAs, we have designed and developed zwitterion-coated exceedingly small superparamagnetic iron oxide nanoparticles (ZES-SPIONs) consisting of ∼3-nm inorganic cores and ∼1-nm ultrathin hydrophilic shell. These ZES-SPIONs are free of Gd and show a high T1 contrast power. We demonstrate the potential of ZES-SPIONs in preclinical MRI and magnetic resonance angiography.

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