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E E Sigmund, S H Baete, K Patel, D Wang, D Stoffel, R Otazo, P Parasoglou, J Bencardino
OBJECTIVES: We describe measurement of skeletal muscle kinetics with multiple echo diffusion tensor imaging (MEDITI). This approach allows characterization of the microstructural dynamics in healthy and pathologic muscle. MATERIALS AND METHODS: In a Siemens 3-T Skyra scanner, MEDITI was used to collect dynamic DTI with a combination of rapid diffusion encoding, radial imaging, and compressed sensing reconstruction in a multi-compartment agarose gel rotation phantom and within in vivo calf muscle...
May 14, 2018: Magma
Anja Müller-Lutz, Alexandra Ljimani, Julia Stabinska, Moritz Zaiss, Johannes Boos, Hans-Jörg Wittsack, Christoph Schleich
PURPOSE: The study compares glycosaminoglycan chemical exchange saturation transfer (gagCEST) imaging of intervertebral discs corrected for solely B0 inhomogeneities or both B0 and B1 inhomogeneities. METHODS: Lumbar intervertebral discs of 20 volunteers were examined with T2 -weighted and gagCEST imaging. Field inhomogeneity correction was performed with B0 correction only and with correction of both B0 and B1 . GagCEST effects measured by the asymmetric magnetization transfer ratio (MTRasym ) and signal-to-noise ratio (SNR) were compared between both methods...
May 14, 2018: Magma
Kannika Khantasup, Pairash Saiviroonporn, Suwatchai Jarussophon, Warangkana Chantima, Tararaj Dharakul
OBJECTIVES: The development of targeted contrast agents for magnetic resonance imaging (MRI) facilitates enhanced cancer imaging and more accurate diagnosis. In the present study, a novel contrast agent was developed by conjugating anti-EpCAM humanized scFv with gadolinium chelate to achieve target specificity. MATERIALS AND METHODS: The material design strategy involved site-specific conjugation of the chelating agent to scFv. The scFv monomer was linked to maleimide-DTPA via unpaired cysteine at the scFv C-terminus, followed by chelation with gadolinium (Gd)...
May 8, 2018: Magma
Johnes Obungoloch, Joshua R Harper, Steven Consevage, Igor M Savukov, Thomas Neuberger, Srinivas Tadigadapa, Steven J Schiff
OBJECTIVES: The need for affordable and appropriate medical technologies for developing countries continues to rise as challenges such as inadequate energy supply, limited technical expertise, and poor infrastructure persist. Low-field magnetic resonance imaging (LF MRI) is a technology that can be tailored to meet specific imaging needs within such countries. Its low power requirements and the possibility of operating in minimally shielded or unshielded environments make it especially attractive...
April 11, 2018: Magma
Manoj Shrestha, Pavel Hok, Ulrike Nöth, Bianca Lienerth, Ralf Deichmann
OBJECTIVE: The purpose of this work was to optimize the acquisition of diffusion-weighted (DW) single-refocused spin-echo (srSE) data without intrinsic eddy-current compensation (ECC) for an improved performance of ECC postprocessing. The rationale is that srSE sequences without ECC may yield shorter echo times (TE) and thus higher signal-to-noise ratios (SNR) than srSE or twice-refocused spin-echo (trSE) schemes with intrinsic ECC. MATERIALS AND METHODS: The proposed method employs dummy scans with DW gradients to drive eddy currents into a steady state before data acquisition...
March 30, 2018: Magma
Thérèse Barbier, Sarra Aissani, Nicolas Weber, Cédric Pasquier, Jacques Felblinger
PURPOSE: To evaluate the function of an active implantable medical device (AIMD) during magnetic resonance imaging (MRI) scans. The induced voltages caused by the switching of magnetic field gradients and rectified radio frequency (RF) pulse were measured, along with the AIMD stimulations. MATERIALS AND METHODS: An MRI-compatible voltage probe with a bandwidth of 0-40 kHz was designed. Measurements were carried out both on the bench with an overvoltage protection circuit commonly used for AIMD and with a pacemaker during MRI scans on a 1...
March 30, 2018: Magma
Nobuyuki Kosaka, Yasuhiro Fujiwara, Tetsuji Kurokawa, Tsuyoshi Matsuda, Masayuki Kanamoto, Naoyuki Takei, Kenji Takata, Jin Takahashi, Yoshio Yoshida, Hirohiko Kimura
OBJECTIVES: We evaluated the vascularity of retained products of conception (RPOC) using arterial spin-labeling magnetic resonance imaging (ASL-MRI) to clarify the clinical feasibility of this approach. MATERIALS AND METHODS: A pulsed-continuous ASL sequence with echo-planar imaging (EPI) acquisitions was used. Ten consecutive patients with RPOC were enrolled. All ASL images were evaluated visually and semiquantitatively and compared with the findings of Doppler ultrasound (US) and dynamic contrast-enhanced MRI (DCE-MRI)...
March 16, 2018: Magma
Morgan Mercredi, Melanie Martin
OBJECT: Recent advances have allowed oscillating gradient (OG) diffusion MRI to infer the sizes of micron-scale axon diameters. Here the effects on the precision of the inferred diameters are studied when reducing the number of images collected to reduce imaging time for clinical feasibility. MATERIALS AND METHODS: Monte Carlo simulations of cosine OG sequences (50-1000 Hz) using a two-compartment model on a parallel cylinder (diameters 1-5 μm) geometry were conducted...
March 7, 2018: Magma
Lukas Reinhold Buschle, Christian H Ziener, Ke Zhang, Volker J F Sturm, Thomas Kampf, Artur Hahn, Gergely Solecki, Frank Winkler, Martin Bendszus, Sabine Heiland, Heinz-Peter Schlemmer, Felix T Kurz
OBJECTIVES: Spin dephasing of the local magnetization in blood vessel networks can be described in the static dephasing regime (where diffusion effects may be ignored) by the established model of Yablonskiy and Haacke. However, for small capillary radii, diffusion phenomena for spin-bearing particles are not negligible. MATERIAL AND METHODS: In this work, we include diffusion effects for a set of randomly distributed capillaries and provide analytical expressions for the transverse relaxation times T2* and T2 in the strong collision approximation and the Gaussian approximation that relate MR signal properties with microstructural parameters such as the mean local capillary radius...
February 24, 2018: Magma
Felix Schyboll, Uwe Jaekel, Bernd Weber, Heiko Neeb
OBJECTIVE: Recent MRI studies have shown that the orientation of nerve fibres relative to the main magnetic field affects the R2 *(= 1/T2 *) relaxation rate in white matter (WM) structures. The underlying physical causes have been discussed in several studies but are still not completely understood. However, understanding these effects in detail is of great importance since this might serve as a basis for the development of new diagnostic tools and/or improve quantitative susceptibility mapping techniques...
February 20, 2018: Magma
Dounia El Hamrani, Amandine Chepied, William Même, Marc Mesnil, Norah Defamie, Sandra Même
OBJECTIVE: Using non-invasive magnetic resonance (MR) techniques and a histological approach, we assessed the outcomes of perinatal exposure at a low dose of 3,3'-DCBPA (2-chloro-4-[1-(3-chloro-4-hydroxyphenyl)-1-methylethyl]phenol) and/or 3,5-DCBPA (2,6-dichloro-4-[1-(4-hydroxyphenyl)-1-methylethyl]phenol) on mice livers. MATERIALS AND METHODS: Fertilized female Swiss mice were injected intraperitoneally during gestation and lactation with either vehicle control, 20 μg/kg/day of BPA, 3,5-DCBPA, 3,3'-DCBPA or a mixture (mix-DCBPA)...
February 20, 2018: Magma
Manohar Latha, Ganesan Kavitha
OBJECTIVE: Schizophrenia (SZ) is a psychiatric disorder that especially affects individuals during their adolescence. There is a need to study the subanatomical regions of SZ brain on magnetic resonance images (MRI) based on morphometry. In this work, an attempt was made to analyze alterations in structure and texture patterns in images of the SZ brain using the level-set method and Laws texture features. MATERIALS AND METHODS: T1-weighted MRI of the brain from Center of Biomedical Research Excellence (COBRE) database were considered for analysis...
February 3, 2018: Magma
Tim Leiner, Gustav Strijkers
No abstract text is available yet for this article.
February 2018: Magma
David Norris
No abstract text is available yet for this article.
February 2018: Magma
Shuo Zhang, Thu Thao Le, Sven Kabus, Boyang Su, Derek J Hausenloy, Stuart A Cook, Calvin W L Chin, Ru San Tan
OBJECTIVE: Our aim was to investigate the technical feasibility of a novel motion compensation method for cardiac magntic resonance (MR) T1 and extracellular volume fraction (ECV) mapping. MATERIALS AND METHODS: Native and post-contrast T1 maps were obtained using modified look-locker inversion recovery (MOLLI) pulse sequences with acquisition scheme defined in seconds. A nonrigid, nonparametric, fast elastic registration method was applied to generate motion-corrected T1 maps and subsequently ECV maps...
February 2018: Magma
Haining Liu, Gregory J Wilson, Niranjan Balu, Jeffrey H Maki, Daniel S Hippe, Wei Wu, Hiroko Watase, Jinnan Wang, Martin L Gunn, Chun Yuan
OBJECTIVES: A postprocessing technique termed 3D true-phase polarity recovery with independent phase estimation using three-tier stacks based region growing (3D-TRIPS) was developed, which directly reconstructs phase-sensitive inversion-recovery images without acquisition of phase-reference images. The utility of this technique is demonstrated in myocardial late gadolinium enhancement (LGE) imaging. MATERIALS AND METHODS: A data structure with three tiers of stacks was used for 3D-TRIPS to directly achieve reliable region growing for successful background-phase estimation...
February 2018: Magma
Bart R Steensma, Ingmar J Voogt, Tim Leiner, Peter R Luijten, Jesse Habets, Dennis W J Klomp, Cornelis A T van den Berg, Alexander J E Raaijmakers
OBJECTIVE: To demonstrate imaging performance for cardiac MR imaging at 7 T using a coil array of 8 transmit/receive dipole antennas and 16 receive loops. MATERIALS AND METHODS: An 8-channel dipole array was extended by adding 16 receive-only loops. Average power constraints were determined by electromagnetic simulations. Cine imaging was performed on eight healthy subjects. Geometrical factor (g-factor) maps were calculated to assess acceleration performance. Signal-to-noise ratio (SNR)-scaled images were reconstructed for different combinations of receive channels, to demonstrate the SNR benefits of combining loops and dipoles...
February 2018: Magma
Marius Menza, Daniela Föll, Jürgen Hennig, Bernd Jung
OBJECTIVE: Myocardial dysfunction of the right ventricle (RV) is an important indicator of RV diseases, e.g. RV infarction or pulmonary hypertension. Tissue phase mapping (TPM) has been widely used to determine function of the left ventricle (LV) by analyzing myocardial velocities. The analysis of RV motion is more complicated due to the different geometry and smaller wall thickness. The aim of this work was to adapt and optimize TPM to the demands of the RV. MATERIALS AND METHODS: TPM measurements were acquired in 25 healthy volunteers using a velocity-encoded phase-contrast sequence and kt-accelerated parallel imaging in combination with optimized navigator strategy and blood saturation...
February 2018: Magma
Eve Piekarski, Teodora Chitiboi, Rebecca Ramb, Larry A Latson, Puneet Bhatla, Li Feng, Leon Axel
OBJECTIVES: Residual respiratory motion degrades image quality in conventional cardiac cine MRI (CCMRI). We evaluated whether a free-breathing (FB) radial imaging CCMRI sequence with compressed sensing reconstruction [extradimensional (e.g. cardiac and respiratory phases) golden-angle radial sparse parallel, or XD-GRASP] could provide better image quality than a conventional Cartesian breath-held (BH) sequence in an unselected population of patients undergoing clinical CCMRI. MATERIALS AND METHODS: One hundred one patients who underwent BH and FB imaging in a midventricular short-axis plane at a matching location were included...
February 2018: Magma
Daniel Giese, Kilian Weiss, Bettina Baeßler, Navid Madershahian, Yeong-Hoon Choi, David Maintz, Alexander C Bunck
OBJECTIVES: The objective of the current work was to evaluate flow and turbulent kinetic energy in different transcatheter aortic valve implants using highly undersampled time-resolved multi-point 3-directional phase-contrast measurements (4D Flow MRI) in an in vitro setup. MATERIALS AND METHODS: A pulsatile flow setup was used with a compliant tubing mimicking a stiff left ventricular outflow tract and ascending aorta. Five different implants were measured using a highly undersampled multi-point 4D Flow MRI sequence...
February 2018: Magma
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