In and Ex Vivo MR Evaluation of Acute Myocardial Ischemia in Pigs by Determining R1 in Steady State After the Administration of the Intravascular Contrast Agent NC100150 Injection

Bjerner, Tomas; Johansson, Lars; Wikström, Gerhard; Ericsson, Anders; Briley-Soebo, Karen; Bjørnerud, Atle; Åhlström, Håkan

doi:10.1097/01.rli.0000128658.63611.b3

Cited by 13 publications

(6 citation statements)

References 40 publications

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“…USPIOs are better candidates since they stay in the blood longer and because their relaxation properties allow their use as positive contrast agents for T 1weighted imaging and angiography. [21][22][23][24][25] Recent and promising applications of maghemite particles are related to cellular and molecular MR imaging. [26][27][28][29][30][31][32] Bulte et al 4 defined molecular imaging as 'the non-invasive and repetitive imaging of targeted macromolecules and biological processes' and cellular imaging as 'the non-invasive and repetitive imaging of targeted cells and cellular processes'.…”

Section: Main Applications In Mrimentioning

confidence: 99%

Magnetic resonance relaxation properties of superparamagnetic particles

Gossuin

Gillis

Hocq

et al. 2009

WIREs Nanomed Nanobiotechnol

258

222

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Nanometric crystals of maghemite are known to exhibit superparamagnetism. Because of the significance of their magnetic moment, maghemite nanoparticles are exceptional contrast agents and are used for magnetic resonance imaging (of the liver, spleen, lymph nodes), for magnetic resonance angiography and for molecular and cellular imaging. The relaxivity of these agents depends on their size, saturation magnetization and magnetic field and also on their degree of clustering. There are different types of maghemite particles whose relaxation characteristics are suited to a specific MRI application. The relaxation induced by maghemite particles is caused by the diffusion of water protons in the inhomogeneous field surrounding the particles. This is well described by a theoretical model that takes magnetite crystal anisotropy and Néel relaxation into account. Another type of superparamagnetic compound is ferritin, the iron-storing protein: it contains a superparamagnetic ferrihydrite core. Even if the resulting magnetic moment of ferritin is far smaller than for magnetite nanoparticles, its massive presence in different organs darkens T(2)-weighted MR images, allowing the noninvasive estimation of iron content, thanks to MRI. The relaxation induced by ferritin in aqueous solutions has been demonstrated to be caused by the exchange of protons between bulk water protons and the surface of the ferrihydrite crystal. However, in vivo, the relaxation properties of ferritin are still unexplained, probably because of protein clustering.

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Section: Main Applications In Mrimentioning

confidence: 99%

Magnetic resonance relaxation properties of superparamagnetic particles

Gossuin

Gillis

Hocq

et al. 2009

WIREs Nanomed Nanobiotechnol

258

222

View full text Add to dashboard Cite

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“…Surgical induction of myocardial infarction in dogs or pigs typically involves thoracotomy with subsequent ligation of a coronary artery [11][12][13]. Balloon catheters have been successfully used for minimally invasive coronary occlusion with subsequent reperfusion [14,15].…”

Section: Introductionmentioning

confidence: 99%

A minimally invasive method for induction of myocardial infarction in an animal model using tungsten spirals

Peukert

Laule

Kaufels

et al. 2009

Int J Cardiovasc Imaging

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Most animal models use surgical thoracotomy with ligation of a coronary artery to induce myocardial infarction. Incision of the chest wall and myocardium affect remodeling after myocardial infarction. The aim of our study was to evaluate a new minimally invasive technique for inducing acute myocardial infarction in pigs. To this end, coronary angiography using a 6-F cardiac catheter was performed in 20 pigs. The cardiac catheter was advanced into the left circumflex artery (LCX) under electrocardiographic monitoring and small tungsten spirals were deployed in the vessel. LCX occlusion was verified by coronary angiography. Two days later, magnetic resonance imaging (MRI) was performed to estimate the extent of infarction. Thereafter, all animals were euthanized and the hearts stained with 2,3,5-triphenyltetrazolium chloride for histologic measurement of infarct size. Tungsten spirals were successfully placed in the LCX in all 20 pigs. About 13 of the 20 animals survived until the end of the experiment. The mean infarct size in the area supplied by the LCX was 4.4 ± 2.3 cm 3 at MRI and 4.3 ± 2.2 cm 3 at histology (r = 0.99, P \ 0.001). No other myocardial regions showed infarction in any of the 13 pigs. Five of nine pigs requiring defibrillation due to ventricular fibrillation died because defibrillation was unsuccessful. One animal each died from pericarditis and pneumonia. Our results show that the minimally invasive method presented here enables reliable induction of myocardial infarction in a fairly straightforward manner. The 25% mortality rate associated with induction of myocardial infarction in our study is comparable to that reported by other investigators.

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“…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.…”

Section: Introductionmentioning

confidence: 99%

“…These effects have been shown to be valuable in the diagnosis of some diseases. 8,17,22 As a tissuespecific MR contrast agent, USPIO has been used to detect lesions in organs where macrophages exhibit strong activity. In these studies, a dosage from 2.5 mg Fe/kg to 16.8 mg Fe/kg has been determined to be safe without side effects or adverse effects in experimental clinical and animal studies.…”

mentioning

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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In and Ex Vivo MR Evaluation of Acute Myocardial Ischemia in Pigs by Determining R1 in Steady State After the Administration of the Intravascular Contrast Agent NC100150 Injection

Abstract: A nearly linear R1 dose response was found in perfused myocardium in vivo. The dose response ex vivo was less steep possibly due to larger water exchange limitations.

Cited by 13 publications

References 40 publications

Magnetic resonance relaxation properties of superparamagnetic particles

Magnetic resonance relaxation properties of superparamagnetic particles

A minimally invasive method for induction of myocardial infarction in an animal model using tungsten spirals

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

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