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Alexia Missoffe, Thérèse Barbier, Jacques Felblinger
OBJECTIVE: To show the relevance of a simple finite difference transmission line model to help design safe implanted cables in 1.5T MRI's using the multi-section cable approach. MATERIALS AND METHODS: The transfer function and heating under a given incident field predicted by the finite difference model for two-section cables are compared to full-wave and experimental results. The finite difference model was then used to design a three-section cable considering the phase effects...
February 19, 2019: Magma
Palmira Villa-Valverde, Ignacio Rodríguez, Daniel Padró, Marina Benito, Carlos Ernesto Garrido-Salmon, Jesús Ruiz-Cabello
OBJECTIVE: Given the growing interest in fluorine, it is necessary to develop new multi-tuned RF coils. Therefore, our objective is to design a simple and versatile double-tuned RF coil that can be used as a transmitter and receiver double-tuned coil (1 H and 19 F) or as transmitter-only double-tuned coil. MATERIALS AND METHODS: A high-pass eight-element birdcage coil was built for 1 H and 19 F for a 7 T scanner. PIN diodes and cable traps to block unwanted common mode currents in cables were introduced to confer more flexibility to the coil...
February 16, 2019: Magma
Rodolfo G Gatto, Allen Q Ye, Luis Colon-Perez, Thomas H Mareci, Anna Lysakowski, Steven D Price, Scott T Brady, Muge Karaman, Gerardo Morfini, Richard L Magin
OBJECTIVE: The goal of this work is to study the changes in white matter integrity in R6/2, a well-established animal model of Huntington's disease (HD) that are captured by ex vivo diffusion imaging (DTI) using a high field MRI (17.6 T). MATERIALS AND METHODS: DTI and continuous time random walk (CTRW) models were used to fit changes in the diffusion-weighted signal intensity in the corpus callosum of controls and in R6/2 mice. RESULTS: A significant 13% decrease in fractional anisotropy, a 7% increase in axial diffusion, and a 33% increase in radial diffusion were observed between R6/2 and control mice...
February 15, 2019: Magma
Sonia Waiczies, Mangala Srinivas, Ulrich Flögel, Philipp Boehm-Sturm, Thoralf Niendorf
No abstract text is available yet for this article.
February 7, 2019: Magma
Mikhail V Gulyaev, Aleksandra V Kuznetsova, Denis N Silachev, Tatyana I Danilina, Lev L Gervits, Yury A Pirogov
OBJECTIVE: To identify the technical aspects of the potential use of clinically approved perfluorodecalin (PFD, C10 F18 ) for 19 F magnetic resonance imaging (MRI) oximetry method at high magnetic field 7.05 T. MATERIALS AND METHODS: 19 F T1 measurements were made on a set of PFD samples with different oxygen contents (0%, 21%, and 100%) at room (21 °C) and body temperature (37 °C). In vivo MRI studies were carried out on one healthy rat and two rats with C6 brain glioma...
February 7, 2019: Magma
Merel Charlotte Postema, Matteo De Marco, Elisa Colato, Annalena Venneri
OBJECTIVE: Resting-state functional magnetic resonance imaging (fMRI) is promising for Alzheimer's disease (AD). This study aimed to examine short-term reliability of the default-mode network (DMN), one of the main haemodynamic patterns of the brain. MATERIALS AND METHODS: Using a 1.5 T Philips Achieva scanner, two consecutive resting-state fMRI runs were acquired on 69 healthy adults, 62 patients with mild cognitive impairment (MCI) due to AD, and 28 patients with AD dementia...
February 7, 2019: Magma
Jan Michálek, Pavla Hanzlíková, Tuan Trinh, Dalibor Pacík
OBJECTIVE: T2 maps are more vendor independent than other MRI protocols. Multi-echo spin-echo signal decays to a non-zero offset due to imperfect refocusing pulses and Rician noise, causing T2 overestimation by the vendor's 2-parameter algorithm. The accuracy of the T2 estimate is improved, if the non-zero offset is estimated as a third parameter. Three-parameter Levenberg-Marquardt (LM) T2 estimation takes several minutes to calculate, and it is sensitive to initial values. We aimed for a 3-parameter fitting algorithm that was comparably accurate, yet substantially faster...
February 7, 2019: Magma
Tohid Mortezazadeh, Elham Gholibegloo, Nader Riyahi Alam, Sadegh Dehghani, Soheila Haghgoo, Hossein Ghanaati, Mehdi Khoobi
OBJECTIVES: In this study, a novel targeted MRI contrast agent was developed by coating gadolinium oxide nanoparticles (Gd2 O3 NPs) with β-cyclodextrin (CD)-based polyester and targeted by folic acid (FA). MATERIALS AND METHODS: The developed Gd2 O3 @PCD-FA MRI contrast agent was characterized and evaluated in relaxivity, in vitro cell targeting, cell toxicity, blood compatibility and in vivo tumor MR contrast enhancement. RESULTS: In vitro cytotoxicity and hemolysis assays revealed that Gd2 O3 @PCD-FA NPs have no significant cytotoxicity after 24 and 48 h against normal human breast cell line (MCF-10A) at concentration of up to 50 µg Gd+3 /mL and have high blood compatibility at concentration of up to 500 µg Gd+3 /mL...
February 7, 2019: Magma
Upasana Tayal, Ricardo Wage, Pedro Filipe Ferreira, Sonia Nielles-Vallespin, Frederick Howard Epstein, Daniel Auger, Xiaodong Zhong, Dudley John Pennell, David Nigel Firmin, Andrew David Scott, Sanjay Kumar Prasad
OBJECTIVE: Develop an accelerated cine displacement encoding with stimulated echoes (DENSE) cardiovascular magnetic resonance (CMR) sequence to enable clinically feasible myocardial strain evaluation in patients with dilated cardiomyopathy (DCM). MATERIALS AND METHODS: A spiral cine DENSE sequence was modified by limiting the field of view in two dimensions using in-plane slice-selective pulses in the stimulated echo. This reduced breath hold duration from 20RR to 14RR intervals...
January 29, 2019: Magma
Sébastien Bär, Thomas Oerther, Matthias Weigel, Angelina Müller, Patrick Hucker, Jan G Korvink, Cheng-Wen Ko, Matthias C Wapler, Jochen Leupold
OBJECTIVE: The applicability of the balanced steady-state free precession (bSSFP) sequence to the field of MR microscopy was investigated, since the potentially high SNR makes bSSFP attractive. However, particularly at ultra-high magnetic fields, a number of constraints emerge: the frequency sensitivity of the bSSFP signal, the duty cycle of the imaging gradients, and the intrinsic diffusion attenuation of the steady state due to the imaging gradients. MATERIALS AND METHODS: Optimization of the bSSFP sequence was performed on three imaging systems (7 T and 9...
January 16, 2019: Magma
Shweta Saini, Hannelie Korf, Sayuan Liang, Rein Verbeke, Bella Manshian, Koen Raemdonck, Ine Lentacker, Conny Gysemans, Stefaan C De Smedt, Uwe Himmelreich
OBJECTIVE: Tracking the autoreactive T-cell migration in the pancreatic region after labeling with fluorinated nanoparticles (1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-[3-(2-pyridyldithio)propionate]-perfluoro-15-crown-5-ether nanoparticles, PDP-PFCE NPs) in a diabetic murine model using 19 F MRI. MATERIALS AND METHODS: Synthesis of novel PDP-PFCE fluorine tracer was performed for in vitro labeling of T cells. Labeling conditions were optimized using different PDP-PFCE NPs concentrations...
January 16, 2019: Magma
Beathe Sitter
OBJECTIVE: To investigate if it was feasible to quantify the renal excretion of topically applied corticosteroids by 19 F MRS. MATERIALS AND METHODS: Five participants, one healthy and four with skin diseases, were treated with ointment containing betamethasone 17-valerate. Urine samples were collected for up to 87 h after the initial application. A sample of ointment mixed with urine served as a study control. Organic fractions were obtained after sample freeze drying, and resolved in deuterated chloroform prior to acquisition of 19 F MR spectra at 470 MHz for typically 8 h...
January 4, 2019: Magma
Niranjan Balu, Zechen Zhou, Daniel S Hippe, Thomas Hatsukami, Mahmud Mossa-Basha, Chun Yuan
OBJECTIVE: To develop a 3D multi-contrast IVW protocol with 0.5-mm isotropic resolution and a scan time of 5 min per sequence. MATERIALS AND METHODS: Pre-contrast T1w VISTA, DANTE prepared PDw VISTA, SNAP, and post-contrast T1w VISTA were accelerated using cartesian undersampling with target ordering method (CUSTOM) and self-supporting tailored k-space estimation for parallel imaging reconstruction (STEP). CUSTOM + STEP IVW was compared to full-sample IVW, SENSE-accelerated IVW, and CUSTOM + zero-filled Fourier reconstruction in normal volunteers and subjects with intracranial atherosclerotic disease (ICAD)...
January 3, 2019: Magma
Svein Are Sirirud Vatnehol, Per Kristian Hol, Atle Bjørnerud, Mahmood Amiry-Moghaddam, Camilla Haglerød, Tryggve Holck Storås
OBJECTIVE: To investigate the effects of a range of parameter settings on T1 measurement stability in the portal vein using the T1-mapping sequences Look-Locker (LL) and Modified Look-Locker inversion recovery (MOLLI). MATERIALS AND METHODS: Ten different versions of LL and MOLLI sequences were tested and compared to a reference sequence provided by the MR manufacturer. Ten healthy volunteers were imaged multiple times on two separate scan days at 3T. The mean T1 values and coefficient of variation (CoV) were calculated for each of the ten sequences and compared to the reference sequence...
January 2, 2019: Magma
Thomas Kampf, Volker J F Sturm, Thomas C Basse-Lüsebrink, André Fischer, Lukas R Buschle, Felix T Kurz, Heinz-Peter Schlemmer, Christian H Ziener, Sabine Heiland, Martin Bendszus, Mirko Pham, Guido Stoll, Peter M Jakob
OBJECTIVE: In magnetic resonance imaging (MRI), compressed sensing (CS) enables the reconstruction of undersampled sparse data sets. Thus, partial acquisition of the underlying k-space data is sufficient, which significantly reduces measurement time. While 19 F MRI data sets are spatially sparse, they often suffer from low SNR. This can lead to artifacts in CS reconstructions that reduce the image quality. We present a method to improve the image quality of undersampled, reconstructed CS data sets...
January 2, 2019: Magma
Karen Holst, Alexander Fyrdahl, Kenneth Caidahl, Martin Ugander, Andreas Sigfridsson
OBJECTIVE: To refine a new technique to measure respiratory-resolved left ventricular end-diastolic volume (LVEDV) in mid-inspiration and mid-expiration using a respiratory self-gating technique and demonstrate clinical feasibility in patients. MATERIALS AND METHODS: Ten consecutive patients were imaged at 1.5 T during 10 min of free breathing using a 3D golden-angle radial trajectory. Two respiratory self-gating signals were extracted and compared: from the k-space center of all acquired spokes, and from a superior-inferior projection spoke repeated every 64 ms...
December 12, 2018: Magma
Guan Wang, Yingli Fu, Steven M Shea, Shashank Sathyanarayana Hegde, Dara L Kraitchman
OBJECTIVES: Peripheral artery disease (PAD) affects 12-14% of the world population, and many are not eligible for conventional treatment. For these patients, microencapsulated stem cells (SCs) offer a novel means to transplant mismatched therapeutic SCs to prevent graft immunorejection. Using c-arm CT and 19 F-MRI for serial evaluation of dual X-ray/MR-visible SC microcapsules (XMRCaps) in a non-immunosuppressed rabbit PAD model, we explore quantitative evaluation of capsule integrity as a surrogate of transplanted cell fate...
December 10, 2018: Magma
Christian Prinz, Paula Ramos Delgado, Thomas Wilhelm Eigentler, Ludger Starke, Thoralf Niendorf, Sonia Waiczies
OBJECTIVE: This study examines the influence of the environmental factor temperature on the 19 F NMR characteristics of fluorinated compounds in phantom studies and in tissue. MATERIALS AND METHODS: 19 F MR mapping and MR spectroscopy techniques were used to characterize the 19 F NMR characteristics of perfluoro-crown ether (PFCE), isoflurane, teriflunomide, and flupentixol. T1 and T2 mapping were performed, while temperature in the samples was changed (T = 20-60 °C) and monitored using fiber optic measurements...
December 4, 2018: Magma
Mingming Wu, Hendrik T Mulder, Yuval Zur, Silke Lechner-Greite, Marion I Menzel, Margarethus M Paulides, Gerard C van Rhoon, Axel Haase
OBJECTIVE: Mild hyperthermia (HT) treatments are generally monitored by phase-referenced proton resonance frequency shift calculations. A novel phase and thus temperature-sensitive fast spin echo (TFSE) sequence is introduced and compared to the double echo gradient echo (DEGRE) sequence. THEORY AND METHODS: For a proton resonance frequency shift (PRFS)-sensitive TFSE sequence, a phase cycling method is applied to separate even from odd echoes. This method compensates for conductivity change-induced bias in temperature mapping as does the DEGRE sequence...
December 4, 2018: Magma
Daniel Jirak, Andrea Galisova, Kristyna Kolouchova, David Babuka, Martin Hruby
Over the last few years, the development and relevance of 19 F magnetic resonance imaging (MRI) for use in clinical practice has emerged. MRI using fluorinated probes enables the achievement of a specific signal with high contrast in MRI images. However, to ensure sufficient sensitivity of 19 F MRI, fluorine probes with a high content of chemically equivalent fluorine atoms are required. The majority of 19 F MRI agents are perfluorocarbon emulsions, which have a broad range of applications in molecular imaging, although the content of fluorine atoms in these molecules is limited...
November 29, 2018: Magma
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