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J M G van Bergen, X Li, J Hua, S J Schreiner, S C Steininger, F C Quevenco, M Wyss, A F Gietl, V Treyer, S E Leh, F Buck, R M Nitsch, K P Pruessmann, P C M van Zijl, C Hock, P G Unschuld
Quantitative Susceptibility Mapping (QSM) MRI at 7 Tesla and 11-Carbon Pittsburgh-Compound-B PET were used for investigating the relationship between brain iron and Amyloid beta (Aβ) plaque-load in a context of increased risk for Alzheimer's disease (AD), as reflected by the Apolipoprotein E ε4 (APOE-e4) allele and mild cognitive impairment (MCI) in elderly subjects. Carriers of APOE-e4 with normal cognition had higher cortical Aβ-plaque-load than non-carriers. In MCI an association between APOE-e4 and higher Aβ-plaque-load was observable both for cortical and subcortical brain-regions...
October 17, 2016: Scientific Reports
Congbo Cai, Xi Chen, Weijun Liu, Shuhui Cai, Delu Zeng, Xinghao Ding
Quantitative susceptibility mapping (QSM) reconstruction is a well-known ill-posed problem. Various regularization techniques have been proposed for solving this problem. In this paper, a rapid method is proposed that uses ℓ0 norm minimization in a gradient domain. Because ℓ0 minimization is an NP-hard problem, a special alternating optimization strategy is employed to simplify the reconstruction algorithm. The proposed algorithm uses only simple point-wise multiplications and thresholding operations, and significantly speeds up the calculation...
October 4, 2016: Computers in Biology and Medicine
Ferdinand Schweser, Simon Daniel Robinson, Ludovic de Rochefort, Wei Li, Kristian Bredies
The elimination of so-called background fields is an essential step in phase MRI and quantitative susceptibility mapping (QSM). Background fields, which are caused by sources outside the region of interest (ROI), are often one to two orders of magnitude stronger than tissue-related field variations from within the ROI, hampering quantitative interpretation of field maps. This paper reviews the current literature on background elimination algorithms for QSM and provides insights into similarities and differences between the many algorithms proposed...
October 7, 2016: NMR in Biomedicine
Dong Zhou, Junghun Cho, Jingwei Zhang, Pascal Spincemaille, Yi Wang
PURPOSE: We assessed the accuracy of quantitative susceptibility mapping in a gadolinium balloon phantom with a large range of susceptibility values and imaging resolutions at 1.5 and 3 Tesla (T). THEORY AND METHODS: The phantom contained sources with susceptibility values of 0.4, 0.8, 1.6, and 3.2 ppm and was imaged at isotropic resolutions of 0.7, 0.8, 1.2, and 1.8 mm. Numerical simulations were performed to match the experimental findings. Voxel sensitivity effects were used to explain the susceptibility underestimations...
October 3, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
H Sun, P Seres, A H Wilman
Standard functional MRI (fMRI), which includes resting-state or paradigm-driven designs, is widely used in studies of brain function, aging, and disease. These fMRI studies typically use two-dimensional gradient echo-planar imaging, which inherently contains phase data that enables quantitative susceptibility mapping (QSM). This work focuses on the dual value of QSM within fMRI studies, by providing both a localized analysis of functional changes in activated tissue, and iron-sensitive structural maps in deep grey matter (DGM)...
September 30, 2016: NMR in Biomedicine
Takuya Hinoda, Yasutaka Fushimi, Tomohisa Okada, Yoshiki Arakawa, Chunlei Liu, Akira Yamamoto, Tsutomu Okada, Kazumichi Yoshida, Susumu Miyamoto, Kaori Togashi
PURPOSE: Gadolinium deposition in dentate nucleus (DN) has been reported after serial administration of gadolinium-based contrast agents (GBCAs). Gadolinium complexes have paramagnetic properties; therefore, we evaluated susceptibility changes of gadolinium deposition in DN using quantitative susceptibility mapping (QSM) for patients after serial administration of GBCAs. MATERIALS AND METHODS: In all, 48 patients with brain tumors, who had had serial GBCA administrations (GBCA group), and 48 healthy volunteers without any history of GBCA administrations (non-GBCA group) were enrolled in this study...
September 24, 2016: Journal of Magnetic Resonance Imaging: JMRI
Melanie Polke, Marcel Sprenger, Kirstin Scherlach, María Cristina Albán-Proaño, Ronny Martin, Christian Hertweck, Bernhard Hube, Ilse D Jacobsen
Morphogenesis in Candida albicans requires hyphal initiation and maintenance, and both processes are regulated by the fungal quorum sensing molecule (QSM) farnesol. We show that deletion of C. albicans EED1, which is crucial for hyphal extension and maintenance, led to a dramatically increased sensitivity to farnesol, and thus identified the first mutant hypersensitive to farnesol. Furthermore, farnesol decreased the transient filamentation of an eed1Δ strain without inducing cell death, indicating that two separate mechanisms mediate quorum sensing and cell lysis by farnesol...
September 14, 2016: Molecular Microbiology
Simon Daniel Robinson, Kristian Bredies, Diana Khabipova, Barbara Dymerska, José P Marques, Ferdinand Schweser
Phase imaging benefits from strong susceptibility effects at very high field and the high signal-to-noise ratio (SNR) afforded by multi-channel coils. Combining the information from coils is not trivial, however, as the phase that originates in local field effects (the source of interesting contrast) is modified by the inhomogeneous sensitivity of each coil. This has historically been addressed by referencing individual coil sensitivities to that of a volume coil, but alternative approaches are required for ultra-high field systems in which no such coil is available...
September 13, 2016: NMR in Biomedicine
Christian Langkammer, Lukas Pirpamer, Stephan Seiler, Andreas Deistung, Ferdinand Schweser, Sebastian Franthal, Nina Homayoon, Petra Katschnig-Winter, Mariella Koegl-Wallner, Tamara Pendl, Eva Maria Stoegerer, Karoline Wenzel, Franz Fazekas, Stefan Ropele, Jürgen Rainer Reichenbach, Reinhold Schmidt, Petra Schwingenschuh
BACKGROUND: Quantitative susceptibility mapping (QSM) and R2* relaxation rate mapping have demonstrated increased iron deposition in the substantia nigra of patients with idiopathic Parkinson's disease (PD). However, the findings in other subcortical deep gray matter nuclei are converse and the sensitivity of QSM and R2* for morphological changes and their relation to clinical measures of disease severity has so far been investigated only sparsely. METHODS: The local ethics committee approved this study and all subjects gave written informed consent...
2016: PloS One
Sarah Eskreis-Winkler, Dong Zhou, Tian Liu, Ajay Gupta, Susan A Gauthier, Yi Wang, Pascal Spincemaille
PURPOSE: Zero padding is a well-studied interpolation technique that improves image visualization without increasing image resolution. This interpolation is often performed as a last step before images are displayed on clinical workstations. Here, we seek to demonstrate the importance of zero padding before rather than after performing non-linear post-processing algorithms, such as Quantitative Susceptibility Mapping (QSM). To do so, we evaluate apparent spatial resolution, relative error and depiction of multiple sclerosis (MS) lesions on images that were zero padded prior to, in the middle of, and after the application of the QSM algorithm...
August 29, 2016: Magnetic Resonance Imaging
Sina Straub, Till M Schneider, Julian Emmerich, Martin T Freitag, Christian H Ziener, Heinz-Peter Schlemmer, Mark E Ladd, Frederik B Laun
PURPOSE: Since quantitative susceptibility mapping (QSM) quantifies magnetic susceptibility relative to a reference value, a suitable reference tissue has to be available to compare different subjects and stages of disease. METHODS: To find such a suitable reference tissue for QSM of the brain, melanoma patients with and without brain metastases were measured. Twelve reference regions were chosen and assessed for stability of susceptibility values with respect to multiple intra-individual and inter-individual measurements, age, and stage of disease...
August 16, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Samir D Sharma, Roland Fischer, Bjoern P Schoennagel, Peter Nielsen, Hendrik Kooijman, Jin Yamamura, Gerhard Adam, Peter Bannas, Diego Hernando, Scott B Reeder
PURPOSE: We aimed to determine the agreement between quantitative susceptibility mapping (QSM)-based biomagnetic liver susceptometry (BLS) and confounder-corrected R2* mapping with superconducting quantum interference device (SQUID)-based biomagnetic liver susceptometry in patients with liver iron overload. METHODS: Data were acquired from two healthy controls and 22 patients undergoing MRI and SQUID-BLS as part of routine monitoring for iron overload. Magnetic resonance imaging was performed on a 3T system using a three-dimensional multi-echo gradient-echo acquisition...
August 11, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Romuald Girard, Maged D Fam, Hussein A Zeineddine, Huan Tan, Abdul Ghani Mikati, Changbin Shi, Michael Jesselson, Robert Shenkar, Meijing Wu, Ying Cao, Nicholas Hobson, Henrik B W Larsson, Gregory A Christoforidis, Issam A Awad
OBJECTIVE Vascular permeability and iron leakage are central features of cerebral cavernous malformation (CCM) pathogenesis. The authors aimed to correlate prospective clinical behavior of CCM lesions with longitudinal changes in biomarkers of dynamic contrast-enhanced quantitative permeability (DCEQP) and quantitative susceptibility mapping (QSM) assessed by MRI. METHODS Forty-six patients with CCMs underwent 2 or more permeability and/or susceptibility studies in conjunction with baseline and follow-up imaging and clinical surveillance during a mean 12...
August 5, 2016: Journal of Neurosurgery
Eo-Jin Hwang, Hyug-Gi Kim, Danbi Kim, Hak Young Rhee, Chang-Woo Ryu, Tian Liu, Yi Wang, Geon-Ho Jahng
PURPOSE: Although a number of studies have focused on finding anatomical regions in which iron concentrations are high, no study has been conducted to examine the overall variations in susceptibility maps of Alzheimer's disease (AD). The objective of this study, therefore, was to differentiate AD from cognitive normal (CN) and mild cognitive impairment (MCI) using a texture analysis of quantitative susceptibility maps (QSMs). METHODS: The study was approved by the local institutional review board, and informed consent was obtained from all subjects...
August 2016: Medical Physics
Zhe Liu, Youngwook Kee, Dong Zhou, Yi Wang, Pascal Spincemaille
PURPOSE: To investigate systematic errors in traditional quantitative susceptibility mapping (QSM) where background field removal and local field inversion (LFI) are performed sequentially, to develop a total field inversion (TFI) QSM method to reduce these errors, and to improve QSM quality in the presence of large susceptibility differences. THEORY AND METHODS: The proposed TFI is a single optimization problem which simultaneously estimates the background and local fields, preventing error propagation from background field removal to QSM...
July 28, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Andreas Deistung, Ferdinand Schweser, Jürgen R Reichenbach
Magnetic susceptibility describes the magnetizability of a material to an applied magnetic field and represents an important parameter in the field of MRI. With the recently introduced method of quantitative susceptibility mapping (QSM) and its conceptual extension to susceptibility tensor imaging (STI), the non-invasive assessment of this important physical quantity has become possible with MRI. Both methods solve the ill-posed inverse problem to determine the magnetic susceptibility from local magnetic fields...
July 19, 2016: NMR in Biomedicine
Sina Straub, Frederik B Laun, Julian Emmerich, Björn Jobke, Henrik Hauswald, Sonja Katayama, Klaus Herfarth, Heinz-Peter Schlemmer, Mark E Ladd, Christian H Ziener, David Bonekamp, Matthias C Röthke
PURPOSE: To evaluate whether quantitative susceptibility (QSM) may be used as an alternative to computed tomography (CT) to detect calcification in prostate cancer patients. MATERIALS AND METHODS: Susceptibility map calculation was performed using 3D gradient echo magnetic resonance imaging (MRI) data from 26 patients measured at 3T who previously received a planning CT of the prostate. Phase images were unwrapped using Laplacian-based phase unwrapping, the background field was removed with the V-SHARP method, and susceptibility maps were calculated with the iLSQR method...
July 15, 2016: Journal of Magnetic Resonance Imaging: JMRI
H M H N Bandara, M J Herpin, D Kolacny, A Harb, D Romanovicz, H D C Smyth
The challenge of eliminating Pseudomonas aeruginosa infections, such as in cystic fibrosis lungs, remains unchanged due to the rapid development of antibiotic resistance. Poor drug penetration into dense P. aeruginosa biofilms plays a vital role in ineffective clearance of the infection. Thus, the current antibiotic therapy against P. aeruginosa biofilms need to be revisited and alternative antibiofilm strategies need to be invented. Fungal quorum sensing molecule (QSM), farnesol, appears to have detrimental effects on P...
August 1, 2016: Molecular Pharmaceutics
Itthi Chatnuntawech, Patrick McDaniel, Stephen F Cauley, Borjan A Gagoski, Christian Langkammer, Adrian Martin, P Ellen Grant, Lawrence L Wald, Kawin Setsompop, Elfar Adalsteinsson, Berkin Bilgic
Quantitative susceptibility mapping (QSM) estimates the underlying tissue magnetic susceptibility from the gradient echo (GRE) phase signal through background phase removal and dipole inversion steps. Each of these steps typically requires the solution of an ill-posed inverse problem and thus necessitates additional regularization. Recently developed single-step QSM algorithms directly relate the unprocessed GRE phase to the unknown susceptibility distribution, thereby requiring the solution of a single inverse problem...
June 22, 2016: NMR in Biomedicine
Pinar Senay Özbay, Andreas Deistung, Xiang Feng, Daniel Nanz, Jürgen Rainer Reichenbach, Ferdinand Schweser
Sophisticated harmonic artifact reduction for phase data (SHARP) is a method to remove background field contributions in MRI phase images, which is an essential processing step for quantitative susceptibility mapping (QSM). To perform SHARP, a spherical kernel radius and a regularization parameter need to be defined. In this study, we carried out an extensive analysis of the effect of these two parameters on the corrected phase images and on the reconstructed susceptibility maps. As a result of the dependence of the parameters on acquisition and processing characteristics, we propose a new SHARP scheme with generalized parameters...
June 3, 2016: NMR in Biomedicine
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