MR Imaging with Ultrasmall Superparamagnetic Iron Oxide Particles in Experimental Soft-Tissue Infections in Rats

Kaim, Achim H.; Wischer, Thorsten; O’Reilly, Terence; Jundt, Gernot; Fröhlich, Johannes; Schulthess, Gustav K. von; Allegrini, Peter R.

doi:10.1148/radiol.2253011485

Cited by 70 publications

(56 citation statements)

References 30 publications

(36 reference statements)

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“…Therefore, it was able to be shown in animal experiments that non-infections synovial inflammation in arthritis models can be imaged using intravenously injected USPIO [173]. In a similar manner, the macrophage presence [174] and the increased extravasation of USPIO [175] in the edge region of bacterial soft tissue abscesses were able to be shown in T2w and T2*w MRI after i. v. USPIO application. Moreover, macrophages were able to be detected experimentally as markers of low-grade chronically inflamed activity of fat tissue in adipose mice after the i. v. injection of USPIO [176].…”

Section: Inflammation Infection and Adiposity Imagingmentioning

confidence: 85%

Superparamagnetic Iron Oxide Nanoparticles in Biomedicine: Applications and Developments in Diagnostics and Therapy

Ittrich¹,

Peldschus²,

Raabe³

et al. 2013

Fortschr Röntgenstr

122

101

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Superparamagnetic iron oxide nanoparticles (SPIO) can be used to image physiological processes and anatomical, cellular and molecular changes in diseases. The clinical applications range from the imaging of tumors and metastases in the liver, spleen and bone marrow, the imaging of lymph nodes and the CNS, MRA and perfusion imaging to atherosclerotic plaque and thrombosis imaging. New experimental approaches in molecular imaging describe undirected SPIO trapping (passive targeting) in inflammation, tumors and associated macrophages as well as the directed accumulation of SPIO ligands (active targeting) in tumor endothelia and tumor cells, areas of apoptosis, infarction, inflammation and degeneration in cardiovascular and neurological diseases, in atherosclerotic plaques or thrombi. The labeling of stem or immune cells allows the visualization of cell therapies or transplant rejections. The coupling of SPIO to ligands, radio- and/or chemotherapeutics, embedding in carrier systems or activatable smart sensor probes and their externally controlled focusing (physical targeting) enable molecular tumor therapies or the imaging of metabolic and enzymatic processes. Monodisperse SPIO with defined physicochemical and pharmacodynamic properties may improve SPIO-based MRI in the future and as targeted probes in diagnostic magnetic resonance (DMR) using chip-based ?NMR may significantly expand the spectrum of in vitro analysis methods for biomarker, pathogens and tumor cells. Magnetic particle imaging (MPI) as a new imaging modality offers new applications for SPIO in cardiovascular, oncological, cellular and molecular diagnostics and therapy. Key Points: Citation Format:

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Section: Inflammation Infection and Adiposity Imagingmentioning

confidence: 85%

Superparamagnetic Iron Oxide Nanoparticles in Biomedicine: Applications and Developments in Diagnostics and Therapy

Ittrich¹,

Peldschus²,

Raabe³

et al. 2013

Fortschr Röntgenstr

122

101

View full text Add to dashboard Cite

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“…Furthermore, the USPIO particles have an R1 relaxivity of approximately 25 seconds −1 nM −1 and an R2 relaxivity of approximately 164 seconds −1 nM −1 at 0.47 T, 37°C in water. 7 Dosages were initially derived from preceding MRA, lymph node inflammation, and macrophage activity in brain ischemia studies published previously, [13][14][15][16][17] in which the dosage of USPIO varied from 2.5 mg Fe/kg to 16.8 mg Fe/kg. Initial experience at our institution with doses 5 mg/kg or more resulted in poor quality images suspected to be due to signal loss from the susceptibility effects of iron within the particles in the cerebral circulation.…”

Section: Contrast Agent Preparationmentioning

confidence: 99%

Dosage Determination of Ultrasmall Particles of Iron Oxide for the Delineation of Microvasculature in the Wistar Rat Brain

Yang

Christoforidis

Figueredo

et al. 2005

Investigative Radiology

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Purpose-This investigation sought to optimize ultrasmall particles of iron oxide (USPIO) contrast agent dosage for visualizing cerebral microvasculature on an 8.0-Tesla ultra high field magnetic resonance imaging system. Materials and Methods-USPIO contrast agent was intravenously administered to 3 groups of 4 rats at 1, 2, and 3 mg Fe/kg. Each animal was scanned before and after injection of USPIO using a high resolution T2*-weighted gradient recalled echo sequence with an in-plane resolution of 78 µm. The signal-to-noise ratio (SNR) and the number of microvessels visualized within the cortex and basal ganglia were calculated and compared before and after the administration of USPIO.Results-As the USPIO dose increased, microvascular conspicuity increased, and SNR decreased. A dosage of 2 mg Fe/kg improved microvascular visualization in both cortex and basal ganglion regions relative to 1 mg Fe/kg without significantly sacrificing SNR as was the case at 3 mg Fe/kg. Conclusion-Two mg Fe/kg USPIO is an optimal dose when imaging normal rat cerebral microvasculature using GRE T2*-weighted MR imaging at a field strength of 8 T. KeywordsUSPIO; magnetic resonance imaging; brain; microvasculature Ultrasmall particles of iron oxide (USPIOs) are magnetic resonance (MR) contrast agents, which are cleared by the polymorphonuclear system. Because of their unique clearance characteristics, the plasma half-life of USPIOs is prolonged and has been categorized as a blood-pool MR contrast agent for magnetic resonance angiography (MRA). [1][2][3][4][5] In these studies, USPIO produced a strong T1 effect to visualize the vessels at conventional 1.5-Tesla (T) magnetic field strength. In addition, USPIO also has a strong T2* effect, which can be detected by T2*-sensitive sequences, such as gradient recalled echo (GRE). [6][7][8] In the central nervous system, the distinct macrophage-microglia is quiescent in the presence of an intact blood-brain barrier. Under physiological conditions, USPIO only circulates in cerebral blood vessels rather than penetrating the blood-brain barrier. 7 This leads to a concentration gradient between cerebral vessels and surrounding brain parenchyma, which provides an opportunity to visualize cerebral microvasculature on steady state T2* GRE sequences. Ultra high field (UHF) MR systems provide significantly higher signal to noise ratio (SNR) and more pronounced susceptibility effect relative to lower field systems. 9-12 These 2 advantages of UHF MRI combined with the use of USPIO intravascular contrast agents make it possible to obtain high-resolution negative-enhanced images of the normal rodent brain microvasculature.The purpose of the present study was to determine the optimal dosage of USPIO in normal Wistar rat brain using an 8-T MRI system. This dosage can then be applied toward the in vivo visualization of microvascularity in rodent brain pathologies such as stroke and glioma. Ultimately, it can serve as a reference for establishing dosages for imaging microvascularity in human pathology. M...

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“…Vol.4, No.6 (2010) 329-338 Available online at www.expresspolymlett.com DOI: 10.3144/expresspolymlett.2010.42 region that they are accumulated, and hence cause negative contrast and provide a dark state in the image where the compounds are accumulated [15]. However, the direct use of magnetic nanoparticles as in vivo MRI contrast agent results in biofouling of the particles in blood plasma and formation of aggregates that are quickly sequestered by cells of the reticular endothelial system (RES) such as macrophages [16,17]. Furthermore, aggregated nanoparticles change their superparamagnetic response [7].…”

mentioning

confidence: 99%

Synthesis and characterization of PVP-functionalized superparamagnetic Fe3O4 nanoparticles as an MRI contrast agent

Arsalani¹,

Fattahi²,

Nazarpoor³

2010

Express Polym. Lett.

225

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Abstract. The magnetite (Fe3O4) nanoparticles (MNPs) coated with poly(N-vinyl pyrrolidone) (PVP) via covalent bonds were prepared as T2 contrast agent for magnetic resonance imaging (MRI). The surface of MNPs was first coated with 3-(trimethoxysilyl) propyl methacrylate (silan A) by a silanization reaction to introduce reactive vinyl groups onto the surface, then poly(N-vinyl pyrrolidone) was grafted onto the surface of modified-MNPs via surface-initiated radical polymerization. The obtained nanoparticles were characterized by FT-IR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), TEM (transmission electron microscopy), VSM (vibrating sample magnetometer), and TGA (thermogravimetric analysis). The MNPs had an average size of 14 nm and exhibited superparamagnetism and high saturation magnetization at room temperature. T2-weighted MRI images of PVP-grafted MNPs showed that the magnetic resonance signal is enhanced significantly with increasing nanoparticle concentration in water. The r1 and r2 values per millimole Fe, and r2/r1 value of the PVP-grafted MNPs were calculated to be 2.6 , 72.1, and 28.1(mmol/l) -1 ·s -1 , respectively. These results indicate that the PVP-grafted MNPs have great potential for application in MRI as a T2 contrast agent. Vol.4, No.6 (2010) 329-338 Available online at www.expresspolymlett.com DOI: 10.3144/expresspolymlett.2010.42 region that they are accumulated, and hence cause negative contrast and provide a dark state in the image where the compounds are accumulated [15]. However, the direct use of magnetic nanoparticles as in vivo MRI contrast agent results in biofouling of the particles in blood plasma and formation of aggregates that are quickly sequestered by cells of the reticular endothelial system (RES) such as macrophages [16,17]. Furthermore, aggregated nanoparticles change their superparamagnetic response [7]. Therefore, in order to minimize biofouling and aggregation of particles and escape from the RES for longer circulation times, the nanoparticles are usually coated with a layer of hydrophilic and biocompatible polymer such as dextran [18], dendrimers [19], poly(ethylene glycol) (PEG) [20], and poly(vinyl pyrrolidone) (PVP) [21][22][23]. Of synthetic polymers, PVP is water-soluble, non-charged, non-toxic, and is used in various medical applications [24]. While there is a potential concern about covalent interaction between hydrophilic polymers and magnetic nanoparticles in order to increase their stability in physiological medium [25][26][27][28][29], PVP coating on Fe 3 O 4 nanoparticles in all previous works has been achieved through noncovalent interaction. Now, polymers grafting of magnetic nanoparticles is one of the most attractive methods of surface modification [30,31]. In the present study, we carried out chemical synthesis and characterization of PVP-functionalized magnetite (Fe 3 O 4 ) nanoparticles. Since the PVP was bonded to the surface of magnetite nanoparticles through covalent bonds, the prepared magnetic fluid (ferrofluid) was ve...

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MR Imaging with Ultrasmall Superparamagnetic Iron Oxide Particles in Experimental Soft-Tissue Infections in Rats

Abstract: Activated macrophages in acute soft-tissue infection can be labeled with USPIOs and detected with MR imaging because of susceptibility effects.

Cited by 70 publications

References 30 publications

Superparamagnetic Iron Oxide Nanoparticles in Biomedicine: Applications and Developments in Diagnostics and Therapy

Superparamagnetic Iron Oxide Nanoparticles in Biomedicine: Applications and Developments in Diagnostics and Therapy

Dosage Determination of Ultrasmall Particles of Iron Oxide for the Delineation of Microvasculature in the Wistar Rat Brain

Synthesis and characterization of PVP-functionalized superparamagnetic Fe3O4 nanoparticles as an MRI contrast agent

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