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Electron paramagnetic resonance: a powerful tool to support magnetic resonance imaging research
The purpose of this paper is to describe some of the areas where electron paramagnetic resonance (EPR) has provided unique information to MRI developments. The field of application mainly encompasses the EPR characterization of MRI paramagnetic contrast agents (gadolinium and manganese chelates, nitroxides) and superparamagnetic agents (iron oxide particles). The combined use of MRI and EPR has also been used to qualify or disqualify sources of contrast in MRI. Illustrative examples are presented with attempts to qualify oxygen sensitive contrast (i.e. T1‐ and T2*‐based methods), redox status or melanin content in tiss...
Source: Contrast Media and Molecular Imaging - September 1, 2014 Category: Radiology Authors: Pierre Danhier, Bernard Gallez Tags: Review Source Type: research

A review of responsive MRI contrast agents: 2005–2014
This review focuses on MRI contrast agents that are responsive to a change in a physiological biomarker. The response mechanisms are dependent on six physicochemical characteristics, including the accessibility of water to the agent, tumbling time, proton exchange rate, electron spin state, MR frequency or superparamagnetism of the agent. These characteristics can be affected by changes in concentrations or activities of enzymes, proteins, nucleic acids, metabolites, or metal ions, or changes in redox state, pH, temperature, or light. A total of 117 examples are presented, including ones that employ nuclei other than 1H, w...
Source: Contrast Media and Molecular Imaging - September 1, 2014 Category: Radiology Authors: Dina V. Hingorani, Adam S. Bernstein, Mark D. Pagel Tags: Review Source Type: research

Monoclonal antibody conjugated magnetic nanoparticles could target MUC‐1‐positive cells in vitro but not in vivo
MUC1 antigen is recognized as a high‐molecular‐weight glycoprotein that is unexpectedly over‐expressed in human breast and other carcinomas. In contrast, C595 a monoclonal antibody (mAb) against the protein core of the human urinary epithelial machine, is commonly expressed in breast carcinomas. The aim of this study was to conjugate ultra‐small super paramagnetic iron oxide nanoparticles (USPIO) with C595 mAb, in order to detect in vivo MUC1 expression. A dual contrast agent (the C595 antibody‐conjugated USPIO labeled with 99mTc) was prepared for targeted imaging and therapy of anti‐MUC1‐expressing cancers. ...
Source: Contrast Media and Molecular Imaging - September 1, 2014 Category: Radiology Authors: Saeed Shanehsazzadeh, Cordula Gruettner, Afsaneh Lahooti, Morteza Mahmoudi, Barry J. Allen, Mahdi Ghavami, Fariba Johari Daha, Mohammad Ali Oghabian Tags: Full Paper Source Type: research

Boron–18F containing positron emission tomography radiotracers: advances and opportunities
Standard [18F]fluorination methods to form carbon–fluorine bonds can have some limitations such as low yield and the requirement for harsh reaction conditions. Inorganic approaches include the formation of boron–[18F]fluorine bonds and have the potential to give high specific activities at room temperature forming a bond that is stable in vivo. There is considerable potential in future applications, particularly in relation to multimodal imaging and the provision of rapid efficient labelling protocols. Copyright © 2014 John Wiley & Sons, Ltd. Standard [18F]fluorination methods to form carbon–fluorine bonds hav...
Source: Contrast Media and Molecular Imaging - August 7, 2014 Category: Radiology Authors: Benjamin P. Burke, Gonçalo S. Clemente, Stephen J. Archibald Tags: Review Source Type: research

In vitro and in vivo characterization of several functionalized ultrasmall particles of iron oxide, vectorized against amyloid plaques and potentially able to cross the blood–brain barrier: toward earlier diagnosis of Alzheimer's disease by molecular imaging
Alzheimer's disease (AD) is a neurodegenerative disorder most often diagnosed 10 years after its onset and development. It is characterized by the accumulation of amyloid‐β peptide (ABP) into amyloid plaques between nerve cells, which produces a massive local neurodegeneration. Molecular magnetic resonance imaging allows diagnosis of AD by showing ABP accumulation in the brain. The ultrasmall particles of iron oxide (USPIO) derivatives proposed in the present work were functionalized with peptides that present an affinity for ABP, independently of its state of aggregation. Their nanomolar Kd* confirms the high affinit...
Source: Contrast Media and Molecular Imaging - July 1, 2014 Category: Radiology Authors: Emilie Ansciaux, Carmen Burtea, Sophie Laurent, Deborah Crombez, Denis Nonclercq, Luce Vander Elst, Robert N. Muller Tags: Full Paper Source Type: research

Conference Abstracts: CMR2013
CONCLUSIONSWe describe a simple preparation of peptide‐decorated microbubbles, contrast agents for ultrasound imaging, and their successful targeting in vitro (adhesion to receptor‐coated surfaces) and in vivo, in a subcutaneous murine tumor model.FINANCIAL INTEREST STATEMENTThe authors do have a direct or indirect financial interest in the products under investigation or subject matter discussed in the manuscript: A. Klibanov is a co‐founder and minority shareholder of Targeson Inc., a startup developing targeted ultrasound contrast for preclinical use (Targeson is not involved in this study in any way and unaware o...
Source: Contrast Media and Molecular Imaging - July 1, 2014 Category: Radiology Tags: Abstracts Source Type: research

Therapy response monitoring of the early effects of a new BRAF inhibitor on melanoma xenograft in mice: evaluation of 18F‐FDG‐PET and 18F‐FLT‐PET
In this study we investigated the feasibility of 18F‐FDG and 18F‐FLT‐PET to monitor the early effects of the BRAFV600E inhibitor in mice with melanoma xenografts. SCID/beige mice with subcutaneous (s.c.) A375 melanoma xenografts, expressing BRAFV600E, received the BRAFV600E inhibitor twice daily orally (0, 25, 50 and 75 mg/kg). At 1, 3 and 7 days after start of therapy, the uptake of 18F‐FDG and 18F‐FLT in the tumor and normal tissues was determined in ex vivo tissue samples. Serial 18F‐FDG and 18F‐FLT‐PET scans were acquired of animals at 1 day before and 1, 3 and 7 days after start of treatment wi...
Source: Contrast Media and Molecular Imaging - July 1, 2014 Category: Radiology Authors: Edwin J. W. Geven, Stefan Evers, Tapan K. Nayak, Mats Bergström, Fei Su, Danny Gerrits, Gerben M. Franssen, Otto C. Boerman Tags: Full Paper Source Type: research

Real‐time cardiac metabolism assessed with hyperpolarized [1‐13C]acetate in a large‐animal model
Dissolution‐dynamic nuclear polarization (dissolution‐DNP) for magnetic resonance (MR) spectroscopic imaging has recently emerged as a novel technique for noninvasive studies of the metabolic fate of biomolecules in vivo. Since acetate is the most abundant extra‐ and intracellular short‐chain fatty acid, we focused on [1‐13C]acetate as a promising candidate for a chemical probe to study the myocardial metabolism of a beating heart. The dissolution‐DNP procedure of Na[1‐13C]acetate for in vivo cardiac applications with a 3 T MR scanner was optimized in pigs during bolus injection of doses of up to 3 mmol. The ...
Source: Contrast Media and Molecular Imaging - July 1, 2014 Category: Radiology Authors: Alessandra Flori, Matteo Liserani, Francesca Frijia, Giulio Giovannetti, Vincenzo Lionetti, Valentina Casieri, Vincenzo Positano, Giovanni Donato Aquaro, Fabio A. Recchia, Maria Filomena Santarelli, Luigi Landini, Jan Henrik Ardenkjaer‐Larsen, Luca Meni Tags: Full Paper Source Type: research

Selective X‐ray contrast enhancement of the spleen of living mice mediated by gold nanorods
In this study, we demonstrate the dramatic properties of gold nanorods (GNR) to serve as robust X‐ray CT contrast‐enhancing agent for selective imaging of the spleen. These organ‐specific uptake properties were delineated by performing longitudinal CT imaging of living mice that were dosed with GNR at 2 day intervals. Rapid uptake in spleen was noted within 12 h of first systemic administration with a change in contrast enhancement of 90 Hounsfield units (ΔHU = 90) and with two subsequent injections a total contrast enhancement of over 200 HU was observed. The resulting images provide excellent contrast that...
Source: Contrast Media and Molecular Imaging - July 1, 2014 Category: Radiology Authors: Connor A. Wathen, Chuck Caldwell, Nripen Chanda, Anandhi Upendran, Ajit Zambre, Zahra Afrasiabi, Sarah E. Chapaman, Nathan Foje, W. Matthew Leevy, Raghuraman Kannan Tags: Full Paper Source Type: research

Thermodynamic stability and kinetic inertness of a Gd–DTPA bisamide complex grafted onto gold nanoparticles
Gold nanoparticles coated by gadolinium (III) chelates (Au@DTDTPA) where DTDTPA is a dithiolated bisamide derivative of diethylenetriamine‐N,N,N′,N′′,N′′‐pentaacetic acid (DTPA), constituted contrast agents for both X‐ray computed tomography and magnetic resonance imaging. In an MRI context, highly stable Gd3+ complexes are needed for in vivo applications. Thus, knowledge of the thermodynamic stability and kinetic inertness of these chelates, when grafted onto gold nanoparticles, is crucial since bisamide DTPA chelates are usually less suited for Gd3+ coordination than DTPA. Therefore, these parameters were...
Source: Contrast Media and Molecular Imaging - July 1, 2014 Category: Radiology Authors: Vijetha Mogilireddy, Isabelle Déchamps‐Olivier, Christophe Alric, Gautier Laurent, Sophie Laurent, Luce Vander Elst, Robert Muller, Rana Bazzi, Stéphane Roux, Olivier Tillement, Françoise Chuburu Tags: Full Paper Source Type: research

Determination of liver‐specific r2* of a highly monodisperse USPIO by 59Fe iron core‐labeling in mice at 3 T MRI
We present a reliable quantification method for local USPIO amount with the estimation of the liver specific relaxivity r2* using monodisperse 59Fe‐core‐labeled USPIO (59FeUSPIO). Dynamic and relaxometric in vivo characteristics of unlabeled monodisperse USPIO were determined in MRI at 3 T. The in vivo MR studies were performed for liver tissue with 59FeUSPIO using iron dosages of 9 (n = 3), 18 (n = 2) and 27 (n = 3) µmol Fe kg−1 body weight. The R2* of the liver before and after USPIO injection (∆R2*) was measured and correlated with 59Fe activity measurements of excised organs by a whole body radioac...
Source: Contrast Media and Molecular Imaging - July 1, 2014 Category: Radiology Authors: Nina Raabe, Evelyn Forberich, Barbara Freund, Oliver T. Bruns, Markus Heine, Michael G. Kaul, Ulrich Tromsdorf, Lena Herich, Peter Nielsen, Rudolph Reimer, Heinrich Hohenberg, Horst Weller, U. Schumacher, Gerhard Adam, Harald Ittrich Tags: Full Paper Source Type: research

Utilization of nanoparticles as X‐ray contrast agents for diagnostic imaging applications
Among all the diagnostic imaging modalities, X‐ray imaging techniques are the most commonly used owing to their high resolution and low cost. The improvement of these techniques relies heavily on the development of novel X‐ray contrast agents, which are molecules that enhance the visibility of internal structures within the body in X‐ray imaging. To date, clinically used X‐ray contrast agents consist mainly of small iodinated molecules that might cause severe adverse effects (e.g. allergies, cardiovascular diseases and nephrotoxicity) in some patients owing to the large and repeated doses that are required to ach...
Source: Contrast Media and Molecular Imaging - July 1, 2014 Category: Radiology Authors: José Carlos De La Vega, Urs O. Häfeli Tags: Review Source Type: research

Solid silica nanoparticles: applications in molecular imaging
Silica and silica‐based nanoparticles have been widely used for therapeutic and diagnostic applications in cancer mainly through delivery of drugs, genes and contrast agents. Development of synthesis methods has provided the possibility of fabricating silica nanoparticles with different sizes in nanometer ranges as well as silica‐based multimodal nanoparticles with many innovative properties and intriguing applications in biomedicine. The surface of silica particles facilitates different methods of surface modifications and allows conjugation of various biomolecules such as proteins and nucleic acids. In this review, d...
Source: Contrast Media and Molecular Imaging - July 1, 2014 Category: Radiology Authors: Vahid Shirshahi, Majid Soltani Tags: Review Source Type: research

Specificity of lectin‐immobilized fluorescent nanospheres for colorectal tumors in a mouse model which better resembles the clinical disease
We have been investigating an imaging agent that enables real‐time and accurate diagnosis of early colorectal cancer at the intestinal mucosa by colonoscopy. The imaging agent is peanut agglutinin‐immobilized polystyrene nanospheres with surface poly(N‐vinylacetamide) chains encapsulating coumarin 6. Intracolonically‐administered lectin‐immobilized fluorescent nanospheres detect tumor‐derived changes through molecular recognition of lectin for the terminal sugar of cancer‐specific antigens on the mucosal surface. The focus of the present study was to evaluate imaging abilities of the nanospheres in animal mod...
Source: Contrast Media and Molecular Imaging - June 28, 2014 Category: Radiology Authors: Tokio Kitamura, Shinji Sakuma, Moe Shimosato, Haruki Higashino, Yoshie Masaoka, Makoto Kataoka, Shinji Yamashita, Ken‐ichiro Hiwatari, Hironori Kumagai, Naoki Morimoto, Seiji Koike, Etsuo Tobita, Robert M. Hoffman, John C. Gore, Wellington Pham Tags: Full Paper Source Type: research

Effect of magnetic field and iron content on NMR proton relaxation of liver, spleen and brain tissues
Iron accumulation is observed in liver and spleen during hemochromatosis and important neurodegenerative diseases involve iron overload in brain. Storage of iron is ensured by ferritin, which contains a magnetic core. It causes a darkening on T2‐weighted MR images. This work aims at improving the understanding of the NMR relaxation of iron‐loaded human tissues, which is necessary to develop protocols of iron content measurements by MRI. Relaxation times measurements on brain, liver and spleen samples were realized at different magnetic fields. Iron content was determined by atomic emission spectroscopy. For all samples...
Source: Contrast Media and Molecular Imaging - June 21, 2014 Category: Radiology Authors: Aline Hocq, Michel Luhmer, Sven Saussez, Stéphane Louryan, Pierre Gillis, Yves Gossuin Tags: Full Paper Source Type: research