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Superparamagnetic Iron Oxide (superparamagnetic + iron_oxide)
Terms modified by Superparamagnetic Iron Oxide Selected AbstractsMR imaging for the longevity of mesenchymal stem cells labeled with poly- L -lysine,Resovist complexesCONTRAST MEDIA & MOLECULAR IMAGING, Issue 2 2010Gang Liu Abstract Superparamagnetic iron oxide (SPIO) nanoparticles are emerging as ideal probes for noninvasive cell tracking. In this study, poly- L -lysine (PLL) was mixed with Resovist to form the PLL,Resovist complexes and the control of the complexes formed by PLL and Resovist and their subsequent properties was easily achievable. MSCs could be safely and efficiently labeled for MR imaging using PLL,Resovist complexes (w/w 0.01:1) and the labeled MSCs could be detected to have definite decreased signal intensity on T2 -weight imaging until 20 days with standard 1.5,T MR equipment. This study describes a simple protocol to label MSCs using PLL,Resovist complexes and the results presented in our study can provide a basis for the application of PLL,Resovist complexes cell labeling. Copyright © 2010 John Wiley & Sons, Ltd. [source] Superparamagnetic iron oxide,enhanced magnetic resonance images of hepatocellular carcinoma: Correlation with histological gradingHEPATOLOGY, Issue 2 2000Ph.D., Yasuharu Imai M.D. Superparamagnetic iron oxide (SPIO),enhanced magnetic resonance (MR) imaging has been used for the detection of hepatic tumors. However, little is known about this technique in relation to hepatocellular carcinoma (HCC). The aim of this study was to investigate whether SPIO,enhanced MR imaging can be useful in assessing histological grades of HCC. The authors studied histologically proven tumors including 31 HCCs and 6 dysplastic nodules. The ratio of the Kupffer-cell count in the tumorous tissue relative to that in the nontumorous tissue (Kupffer-cell,count ratio) decreased as HCCs became less well differentiated. The ratio of the intensity of the tumorous lesion to that of the nontumorous area on SPIO,enhanced MR images (SPIO intensity ratio) correlated inversely with Kupffer-cell,count ratio in HCCs and dysplastic nodules (r = ,.826, P< .001) and increased as the degree of differentiation of HCCs decreased, indicating that the uptake of SPIO in HCCs decreased as the degree of differentiation of HCCs declined. All of the dysplastic nodules and some well-differentiated HCCs showed hypointense or isointense enhancement, relative to the surrounding liver parenchyma, indicating greater or similar uptake of SPIO in the tumor when compared with nontumorous areas. These results suggest that SPIO,enhanced MR imaging reflects Kupffer-cell numbers in HCCs and dysplastic nodules, and is useful for estimation of histological grading in HCCs, although uncertainties persist in differentiating dysplastic nodules from well-differentiated HCCs. [source] Magnetically Separable Gold Catalyst for the Aerobic Oxidation of AminesCHEMCATCHEM, Issue 1 2009Linda Aschwanden Abstract A magnetically separable, recyclable gold catalyst consisting of gold nanoparticles supported on intimately mixed superparamagnetic ceria/iron oxide has been prepared by simple addition of the preformed mixed oxide support and the gold precursor, Au(OAc)3, to the reaction mixture of the aerobic oxidation of amines. The catalyst was characterized by means of X-ray diffraction (XRD), N2 adsorption, superconducting quantum-interference device (SQUID) measurements, time-of-flight secondary ion mass spectrometry (TOF-SIMS), scanning transmission electron microscopy (STEM), and scanning electron microscopy with an energy-dispersive X-ray spectrometer (SEM-EDAX). Catalytic tests with various amines showed high selectivity to the corresponding imines (87,100,%), and good separation efficiency and recyclability of the catalyst. [source] Proposing magnetic nanoparticle hyperthermia in low-field MRICONCEPTS IN MAGNETIC RESONANCE, Issue 1 2010Pádraig Cantillon-Murphy Abstract This work examines feasibility, practical advantages, and disadvantages of a combined MRI/magnetic particle hyperthermia (MPH) system for cancerous tumor treatment in low perfusion tissue. Although combined MRI/hyperthermia systems have been proposed and constructed, the current proposal differs because the hyperthermia system would be specifically designed to interact with the magnetic nanoparticles injected at the tumor site. The proposal exploits the physical similarities between the magnetic nanoparticles currently employed for MPH and those used as superparamagnetic iron oxide (SPIO) contrast agents in MR imaging. The proposal involves the addition of a rotating magnetic field RF hyperthermia source perpendicular to the MRI B0 field which operates in a similar manner to the MRI RF excitation field, B1, but at significantly higher frequency and field strength such that the magnetic nanoparticles are forced to rotate in its presence. This rotation is the source of increases in temperature which are of therapeutic benefit in cancer therapy. For rotating magnetic fields with amplitudes much smaller than B0, the nanoparticles' suspension magnetization rapidly saturates with increasing B0. Therefore, the proposal is best suited to low-field MRI systems when magnetic saturation is incomplete. In addition, careful design of the RF hyperthermia source is required to ensure no physical or RF interference with the B1 field used for MRI excitation. Notwithstanding these caveats, the authors have shown that localized steady-state temperature rises in small spherical tumors of up to 10°C are conceivable with careful selection of the nanoparticle radius and concentration, RF hyperthermia field amplitude and frequency. © 2010 Wiley Periodicals, Inc. Concepts Magn Reson Part A 36A: 36,47, 2010. [source] Inorganic Nanoparticles for MRI Contrast AgentsADVANCED MATERIALS, Issue 21 2009Hyon Bin Na Abstract Various inorganic nanoparticles have been used as magnetic resonance imaging (MRI) contrast agents due to their unique properties, such as large surface area and efficient contrasting effect. Since the first use of superparamagnetic iron oxide (SPIO) as a liver contrast agent, nanoparticulate MRI contrast agents have attracted a lot of attention. Magnetic iron oxide nanoparticles have been extensively used as MRI contrast agents due to their ability to shorten T2* relaxation times in the liver, spleen, and bone marrow. More recently, uniform ferrite nanoparticles with high crystallinity have been successfully employed as new T2 MRI contrast agents with improved relaxation properties. Iron oxide nanoparticles functionalized with targeting agents have been used for targeted imaging via the site-specific accumulation of nanoparticles at the targets of interest. Recently, extensive research has been conducted to develop nanoparticle-based T1 contrast agents to overcome the drawbacks of iron oxide nanoparticle-based negative T2 contrast agents. In this report, we summarize the recent progress in inorganic nanoparticle-based MRI contrast agents. [source] Magnetite-Loaded Polymeric Micelles as Ultrasensitive Magnetic-Resonance Probes,ADVANCED MATERIALS, Issue 16 2005H. Ai Increased contrast in magnetic resonance imaging (MRI) is accomplished using polymeric micelles loaded with superparamagnetic iron oxide (SPIO) nanoparticles encapsulated in biocompatible, biodegradable poly(,-caprolactone)- b -poly(ethylene glycol) (PCL- b -PEG) copolymers (see Figure). The loaded micelles show significantly improved T2 relaxivities and remarkable MRI detection sensitivity. [source] Ferucarbotran expands area treated by radiofrequency ablation in rabbit liversJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 7pt2 2008Tatsuya Miyake Abstract Background and Aim:, Several studies have examined the factors involved with expansion of the coagulation volume following radiofrequency ablation (RFA). Ferucarbotran contains superparamagnetic iron oxide that generates heat in a radiofrequency electric field and may have an effect on the area affected by RFA. We attempted to determine whether ferucarbotran administration expands radiofrequency-ablated volume using a rabbit model. Methods:, A total of 15 male Japanese white rabbits (16 weeks old) were used and divided into three groups of five each. A 1-mL saline solution was given intravenously into a dorsal ear vein in the control group, whereas 1 mL ferucarbotran solution (0.016 mL/kg bodyweight) was given to the common-dose group and 1 mL of a twofold concentrated ferucarbotran solution (0.032 mL/kg bodyweight) was given to the high-dose group. RFA was performed with a cool-tip electrode 4 h after the administration and immediately thereafter the rabbits were killed, and the volume of the ablated area measured using magnetic resonance imaging (MRI). Following the MRI analysis, the rabbit's livers were resected, and the maximum short axis diameter of the ablated area in each was measured. Results:, None of the rabbits died during the RFA procedure. The volume of the ablated area estimated on MR images in the ferucarbotran-administered groups was larger than that in the control group. Further, our macroscopic assessment showed that the maximum short axis diameter had a tendency to increase with ferucarbotran administration. Conclusion:, Ferucarbotran may expand the area treated by RFA. [source] Quantification of superparamagnetic iron oxide-mediated signal intensity change in patients with liver cirrhosis using T2 and T2* mapping: A preliminary reportJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2010Yong Eun Chung MD Abstract Purpose: To quantify the accumulation of superparamagnetic iron oxide (SPIO) in patients with and without liver cirrhosis using T2 and T2* mapping. Materials and Methods: We enrolled 10 patients without liver cirrhosis and 30 patients with liver cirrhosis (Child-Pugh class A, n = 18; and B/C, n = 12). T2 and T2* mapping were performed before and after SPIO administration. The reductions in T2 (,T2) and T2* (,T2*) after SPIO administration were compared between the control and liver cirrhosis groups and the control, Child-Pugh A, and Child Pugh B/C groups. Results: There were significant differences in ,T2 (22.2 ± 4.4 and 15.1 ± 7.0) and ,T2* values (24.3 ± 3.3 and 16.8 ± 8.1) (P = 0.005 and P < 0.001) between the control and the liver cirrhosis groups. There was a significant difference in the ,T2* between the Child-Pugh A and Child-Pugh B/C groups (P < 0.001) and in the ,T2 and ,T2* between the control and Child-Pugh B/C groups (P = 0.018 and P < 0.001). Conclusion: ,T2 and ,T2* are significantly larger in patients without liver cirrhosis than those with liver cirrhosis. ,T2* is also significantly larger in Child-Pugh class A patients than those in Child-Pugh B/C. J. Magn. Reson. Imaging 2010;31:1379,1386. © 2010 Wiley-Liss, Inc. [source] Comparison of ferucarbotran-enhanced fluid-attenuated inversion-recovery echo-planar, T2-weighted turbo spin-echo, T2*-weighted gradient-echo, and diffusion-weighted echo-planar imaging for detection of malignant liver lesionsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2010Yoshihiko Fukukura MD Abstract Purpose: To compare the diagnostic accuracy of superparamagnetic iron oxide (SPIO)-enhanced fluid-attenuated inversion-recovery echo-planar imaging (FLAIR EPI) for malignant liver tumors with that of T2-weighted turbo spin-echo (TSE), T2*-weighted gradient-echo (GRE), and diffusion-weighted echo-planar imaging (DW EPI). Materials and Methods: SPIO-enhanced magnetic resonance imaging (MRI) that included FLAIR EPI, T2-weighted TSE, T2*-weighted GRE, and DW EPI sequences was performed using a 3 T system in 54 consecutive patients who underwent surgical exploration with intraoperative ultrasonography. A total of 88 malignant liver tumors were evaluated. Images were reviewed independently by two blinded observers who used a 5-point confidence scale to identify lesions. Results were correlated with results of histopathologic findings and surgical exploration with intraoperative ultrasonography. The accuracy of each MRI sequence was measured with jackknife alternative free-response receiver operating characteristic analysis. The sensitivity of each observer with each MRI sequence was compared with McNemar's test. Results: Accuracy values were significantly higher with FLAIR EPI sequence (0.93) than with T2*-weighted GRE (0.80) or DW EPI sequences (0.80) (P < 0.05). Sensitivity was significantly higher with the FLAIR EPI sequence than with any of the other sequences. Conclusion: SPIO-enhanced FLAIR EPI sequence was more accurate in the diagnosis of malignant liver tumors than T2*-weighted GRE and DW EPI sequences. SPIO-enhanced FLAIR EPI sequence is helpful for the detection of malignant liver tumors. J. Magn. Reson. Imaging 2010;31:607,616. ©2010 Wiley-Liss, Inc. [source] In vivo magnetic resonance imaging of iron oxide,labeled, arterially-injected mesenchymal stem cells in kidneys of rats with acute ischemic kidney injury: Detection and monitoring at 3TJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2007Harald Ittrich MD Abstract Purpose To evaluate MRI for a qualitative and quantitative in vivo tracking of intraaortal injected iron oxide,labeled mesenchymal stem cells (MSC) into rats with acute kidney injury (AKI). Materials and Methods In vitro MRI and R2* measurement of nonlabeled and superparamagnetic iron oxide (SPIO)-labeled MSC (MSCSPIO) was performed in correlation to cellular iron content and cytological examination (Prussian blue, electron microscopy). In vivo MRI and R2* evaluation were performed before and after ischemic/reperfusion AKI (N = 14) and intraaortal injection of 1.5 × 106 MSCSPIO (N = 7), fetal calf serum (FCS) (medium, N = 6), and SPIO alone (N = 1) up to 14 days using a clinical 3T scanner. Signal to noise ratios (SNR), R2* of kidneys, liver, spleen, and bone marrow, renal function (creatinine [CREA], blood urea nitrogen [BUN]), and kidney volume were measured and tested for statistical significance (Student's t -test, P < 0.05) in comparison histology (hematoxylin and eosin [H&E], Prussian blue, periodic acid-Schiff [PAS], CD68). Results In vitro, MSCSPIO showed a reduction of SNR and T2* with R2* , number of MSCSPIO (R2 = 0.98). In vivo MSCSPIO administration resulted in a SNR decrease (35 ± 15%) and R2* increase (101 ± 18.3%) in renal cortex caused by MSCSPIO accumulation in contrast to control animals (P < 0.01). Liver, spleen, and bone marrow (MSCSPIO) showed a delayed SNR decline/R2* increase (P < 0.05) resulting from MSCSPIO migration. The increase of kidney volume and the decrease in renal function (P < 0.05) was reduced in MSC-treated animals. Conclusion Qualitative and quantitative in vivo cell-tracking and monitoring of organ distribution of intraaortal injected MSCSPIO in AKI is feasible in MRI at 3T. J. Magn. Reson. Imaging 2007;25:1179,1191. © 2007 Wiley-Liss, Inc. [source] Diffusion-weighted images of the liver: Comparison of tumor detection before and after contrast enhancement with superparamagnetic iron oxideJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2005Shinji Naganawa MD Abstract Purpose To study the recognition of malignant lesions of the liver on diffusion-weighted images (DWI) can be improved by the administration of superparamagnetic iron oxide (SPIO). Materials and Methods Pre- and post-SPIO mediated DWI of the liver was compared in six patients with suspected malignant liver lesions at 1.5 Tesla using a parallel imaging technique. Results Post-SPIO DWI showed improved contrast-to-noise ratio between malignant lesions and liver. Furthermore, the spleen signal was decreased on post-SPIO DWI, thus avoiding the overlap of the spleen and left lobe of the liver on maximum intensity projections (MIP). Conclusion Recognition of malignant lesions of the liver was improved by SPIO on DWI. On MIP images of DWI, SPIO helped to decrease the overlap of spleen signal on the liver in some projection angles. J. Magn. Reson. Imaging 2005;21:836,840. © 2005 Wiley-Liss, Inc. [source] Predictability of FTY720 efficacy in experimental autoimmune encephalomyelitis by in vivo macrophage tracking: Clinical implications for ultrasmall superparamagnetic iron oxide-enhanced magnetic resonance imagingJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2004Martin Rausch PhD Abstract Purpose To examine the efficacy of FTY720 as a new agent to reduce inflammatory activity in an animal model of multiple sclerosis (MS) by in vivo macrophage tracking. Material and Methods FTY720 was used for treatment of rats in a model of chronic relapsing experimental autoimmune encephalomyelitis (EAE) at an oral dose of 0.3 mg/kg/day. Magnetic resonance imaging (MRI) based on in vivo tracking of macrophages labeled with ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles, immunohistological staining (IHC), and neurological readouts was used to study the burden of disease in treated and untreated animals. Results While untreated animals showed severe paralysis of the hind paws, intense accumulation of macrophages in brain tissue, and areas of blood-brain barrier (BBB) disruption, FTY720-treated animals displayed no signs of inflammatory activity or neurological impairment. These observations were made for both acute phase and first relapse. Conclusion Tracking of macrophages by MRI provides direct evidence of the immunomodulatory efficacy of FTY720 in the EAE model and correlates well with neurological symptoms and histology. J. Magn. Reson. Imaging 2004;20:16,24. © 2004 Wiley-Liss, Inc. [source] Conserved fate and function of ferumoxides-labeled neural precursor cells in vitro and in vivoJOURNAL OF NEUROSCIENCE RESEARCH, Issue 5 2010Mikhal E. Cohen Abstract Recent progress in cell therapy research for brain diseases has raised the need for non-invasive monitoring of transplanted cells. For therapeutic application in multiple sclerosis, transplanted cells need to be tracked both spatially and temporally, in order to assess their migration and survival in the host tissue. Magnetic resonance imaging (MRI) of superparamagnetic iron oxide-(SPIO)-labeled cells has been widely used for high resolution monitoring of the biodistribution of cells after transplantation into the central nervous system (CNS). Here we labeled mouse glial-committed neural precursor cells (NPCs) with the clinically approved SPIO contrast agent ferumoxides and examined their survival and differentiation in vitro, as well as their functional response to environmental signals present within the inflamed brain of experimental autoimmune encephalomyelitis (EAE) mice in vivo. We show that ferumoxides labeling does not affect NPC survival and pluripotency in vitro. Following intracerebroventricular (ICV) transplantation in EAE mice, ferumoxides-labeled NPCs responded to inflammatory cues in a similar fashion as unlabeled cells. Ferumoxides-labeled NPCs migrated over comparable distances in white matter tracts and differentiated equally into the glial lineages. Furthermore, ferumoxides-labeled NPCs inhibited lymph node cell proliferation in vitro, similarly to non-labeled cells, suggesting a preserved immunomodulatory function. These results demonstrate that ferumoxides-based MRI cell tracking is well suited for non-invasive monitoring of NPC transplantation. © 2009 Wiley-Liss, Inc. [source] Magneto-motive detection of tissue-based macrophages by differential phase optical coherence tomographyLASERS IN SURGERY AND MEDICINE, Issue 3 2007Junghwan Oh PhD Abstract Background and Objectives A novel method to detect tissue-based macrophages using a combination of superparamagnetic iron oxide (SPIO) nanoparticles and differential phase optical coherence tomography (DP-OCT) with an external oscillating magnetic field is reported. Study Design/Material and Methods Magnetic force acting on iron-laden tissue-based macrophages was varied by applying a sinusoidal current to a solenoid containing a conical iron core that substantially focused and increased magnetic flux density. Results Nanoparticle motion was detected with DP-OCT, which can detect tissue movement with nanometer resolution. Frequency response of iron-laden tissue movement was twice the modulation frequency since the magnetic force is proportional to the product of magnetic flux density and gradient. Conclusions Results of our experiments indicate that DP-OCT can be used to identify tissue-based macrophage when excited by an external focused oscillating magnetic field. Lasers Surg. Med. 39:266,272, 2007. © 2007 Wiley-Liss, Inc. [source] MR tracking of transplanted cells with "positive contrast" using manganese oxide nanoparticlesMAGNETIC RESONANCE IN MEDICINE, Issue 1 2008Assaf A. Gilad Abstract Rat glioma cells were labeled using electroporation with either manganese oxide (MnO) or superparamagnetic iron oxide (SPIO) nanoparticles. The viability and proliferation of SPIO-labeled cells (1.9 mg Fe/ml) or cells electroporated with a low dose of MnO (100 ,g Mn/ml) was not significantly different from unlabeled cells; a higher MnO dose (785 ,g Mn/ml) was found to be toxic. The cellular ion content was 0.1,0.3 pg Mn/cell and 4.4 pg Fe/cell, respectively, with cellular relaxivities of 2.5,4.8 s,1 (R1) and 45,84 s,1 (R2) for MnO-labeled cells. Labeled cells (SPIO and low-dose MnO) were each transplanted in contralateral brain hemispheres of rats and imaged in vivo at 9.4T. While SPIO-labeled cells produced a strong "negative contrast" due to the increase in R2, MnO-labeled cells produced "positive contrast" with an increased R1. Simultaneous imaging of both transplants with opposite contrast offers a method for MR "double labeling" of different cell populations. Magn Reson Med 60:1,7, 2008. © 2008 Wiley-Liss, Inc. [source] Monitoring transplanted human mesenchymal stem cells in rat and rabbit bladders using molecular magnetic resonance imaging,NEUROUROLOGY AND URODYNAMICS, Issue 4 2007Yun Seob Song Abstract Aims This study investigated whether superparamagnetic iron oxide (SPIO)-labeled human mesenchymal stem cells (hMSCs) may be monitored non-invasively by in vivo magnetic resonance (MR) imaging with conventional 1.5-T system examinations in the bladders of rats and rabbits. Methods SPIO were transferred to hMSCs, using GenePORTER. After SPIO-labeled hMSCs were transplanted into the animal bladders, serial T2-weighted MR images and histological examinations were performed over a 4-week period. Results hMSCs loaded with SPIO, compared to unlabeled cells, showed similar viability. SPIO-labeled hMSCs underwent normal chondrogenic, adipogenic, and osteogenic differentiation. For SPIO-labeled hMSCs concentrations that were greater than 1,×,105, in vitro MR images showed a decrease in signal intensity. MR signal intensity at the areas of SPIO-labeled hMSCs in rat and rabbit bladders were decreased and confined locally. After injection of SPIO-labeled hMSCs into the bladder, MR imaging demonstrated that hMSCs could be seen for at least 12 weeks post-injection. The presence of iron was confirmed with Prussian blue staining in histological sections. Conclusions Our findings suggest that hMSCs in animal bladders can be monitored non-invasively with conventional MR imaging. Neurourol. Urodynam. 26:584,593, 2007. © 2007 Wiley-Liss, Inc. [source] | ||||||||||