NMR in Biomedicine

Cover image for Vol. 30 Issue 2

Early View (Online Version of Record published before inclusion in an issue)

Impact Factor: 2.983

ISI Journal Citation Reports © Ranking: 2015: 10/43 (Spectroscopy); 26/72 (Biophysics); 26/124 (Radiology Nuclear Medicine & Medical Imaging)

Online ISSN: 1099-1492

Associated Title(s): Contrast Media & Molecular Imaging

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  1. 1 - 54
  1. RESEARCH ARTICLES

    1. You have full text access to this OnlineOpen article
      VERSE-guided parallel RF excitations using dynamic field correction

      Mustafa Çavuşoğlu, Ronald Mooiweer, Klaas P. Pruessmann and Shaihan J. Malik

      Version of Record online: 17 FEB 2017 | DOI: 10.1002/nbm.3697

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      The experimental performance of the parallel RF excitations performed by the VERSEd RF and gradient waveforms strictly depend on the fidelity of the gradient fields. In order to improve the excitation accuracy besides limiting the RF power below certain thresholds, we propose to integrate gradient field monitoring or gradient impulse response function (GIRF) estimations of the actual gradient fields into the RF pulse design problem using a third order dynamic field camera.

    2. A parametric model of the brain vascular system for estimation of the arterial input function (AIF) at the tissue level

      Siamak P. Nejad-Davarani, Hassan Bagher-Ebadian, James R. Ewing, Douglas C. Noll, Tom Mikkelsen, Michael Chopp and Quan Jiang

      Version of Record online: 17 FEB 2017 | DOI: 10.1002/nbm.3695

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      We present a model of the cerebral vascular system based on vascular morphology and laws of fluid dynamics, to be used for estimating the local arterial input function in DSC and DCE MRI and DCE-CT studies. Using this local arterial input function can reduce errors in estimation of permeability and perfusion parameters in these studies. The model was tested on DCE-CT images by creating an arrival time map using the model parameters, which matched the expected values in the brain.

    3. An extended vascular model for less biased estimation of permeability parameters in DCE-T1 images

      Siamak P. Nejad-Davarani, Hassan Bagher-Ebadian, James R. Ewing, Douglas C. Noll, Tom Mikkelsen, Michael Chopp and Quan Jiang

      Version of Record online: 17 FEB 2017 | DOI: 10.1002/nbm.3698

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      We have introduced a model of the brain vascular system for simultaneously describing blood flow and contrast agent extravasation to the extravascular extracellular space, to be used for estimating the local arterial input function (AIF) and permeability parameters. Simulations show that using this model-corrected local AIF instead of the global AIF can lead to less biased estimates of the permeability parameters in pharmacokinetic models. Testing the two AIFs on DCE-T1 images of cerebral tumors showed similar trends in the estimated values of the permeability parameters to the simulated signals.

    4. Spatiotemporal microstructural white matter changes in diffusion tensor imaging after transient focal ischemic stroke in rats

      Won-Beom Jung, Yong Hee Han, Julius Juhyun Chung, Sun Young Chae, Sung Hoon Lee, Geun Ho Im, JiHoon Cha and Jung Hee Lee

      Version of Record online: 16 FEB 2017 | DOI: 10.1002/nbm.3704

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      Spatiotemporal white matter changes were examined to reflect the ongoing processes for tissue damage and spontaneous recovery after stroke in rat with DTI-derived parameters using tract-based spatial statistics. Fractional anisotropy remained unchanged initially, followed by continuous decrease in the ipsilesional hemisphere at the acute stage and gradual recovery later. Alterations of the other parameters showed patterns of initial decrease, subsequent pseudo-normalizations in mean and axial diffusivity, rapid reduction in radial diffusivity, and progressive increase in all of them with decreased areas later.

    5. An adaptive model for rapid and direct estimation of extravascular extracellular space in dynamic contrast enhanced MRI studies

      Azimeh N.V. Dehkordi, Alireza Kamali-Asl, James R. Ewing, Ning Wen, Indrin J. Chetty and Hassan Bagher-Ebadian

      Version of Record online: 14 FEB 2017 | DOI: 10.1002/nbm.3682

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      Extra-vascular extra-cellular space (ve) is an important parameter in tumor studies; it can characterize tumor proliferative and aggressiveness, and provide valuable information about the tumor microenvironment. A well-trained Adaptive Neural Network (ANN) for estimation of ve from temporal ΔR1 profile, is less sensitive to noise and produced a less biased estimate of ve compared to the MLE method. This adaptive estimator can be accurately employed in clinical application as a rapid, direct and relatively unbiased ve estimator.

    6. You have full text access to this OnlineOpen article
      Extended RF shimming: Sequence-level parallel transmission optimization applied to steady-state free precession MRI of the heart

      Arian Beqiri, Anthony N. Price, Francesco Padormo, Joseph V. Hajnal and Shaihan J. Malik

      Version of Record online: 14 FEB 2017 | DOI: 10.1002/nbm.3701

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      We present a ‘sequence-level’ RF shimming optimization for minimization of TR for balanced SSFP 3 T cardiac MRI using an 8-channel body-coil. We optimize RF shims alongside sequence variables while respecting hardware and safety constraints. Two optimizations were compared to quadrature mode operation; one seeking to achieve the correct flip angle (‘minimum bias’) and one seeking to improve homogeneity (‘mean-square-error’). The latter produced 32 ± 3% reduction in imaging duration for 7 male subjects with 32 ± 8% improvement in flip angle homogeneity.

    7. Optimization of inhomogeneous magnetization transfer (ihMT) MRI contrast for preclinical studies using dipolar relaxation time (T1D) filtering

      V.H. Prevost, O.M. Girard, S. Mchinda, G. Varma, D.C. Alsop and G. Duhamel

      Version of Record online: 14 FEB 2017 | DOI: 10.1002/nbm.3706

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      A strategy based on filtering of the signal of short T1D components was used to optimize the inhomogeneous magnetization transfer (ihMT) contrast for long T1D myelinated structures in mouse. Typical ihMT ratio (ihMTR) values on the order of 4-5% in white matter (WM), 2.5% in gray matter (GM) and 1-1.3% in muscle were obtained, thus leading to high positive relative ihMTR contrasts between myelinated tissues and other tissues. Of particular importance, the relative ihMTR contrast between WM and GM (˜2) appeared to be relatively independent of the saturation parameters.

    8. Phase imaging with multiple phase-cycled balanced steady-state free precession at 9.4 T

      Jae-Woong Kim, Seong-Gi Kim and Sung-Hong Park

      Version of Record online: 10 FEB 2017 | DOI: 10.1002/nbm.3699

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      Multiple phase-cycled bSSFP phase images showed stronger phase contrast and better visibility of complex brain structures than GRE phase images in overall brain regions under the same total scan time at 9.4 T. However, the phase fMRI signals were weak overall and mostly located in draining veins for both bSSFP and GRE. Multiple phase-cycled bSSFP phase imaging is a promising anatomical imaging technique at high field, while its usage as fMRI does not seem desirable with the current approach.

    9. Parallel transmission RF pulse design with strict temperature constraints

      Cem M. Deniz, Giuseppe Carluccio and Christopher Collins

      Version of Record online: 10 FEB 2017 | DOI: 10.1002/nbm.3694

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      There is increasing interest in using temperature to ensure safety in MRI. In this study, we present a local temperature correlation matrix formalism and apply it to impose strict constraints on maximum absolute temperature in parallel transmission RF pulse design for head and hip regions. The use of temperature correlation matrices resulted in better excitation fidelity compared with the use of SAR, while the safety of the subject is always guaranteed.

    10. On the Contribution of Curl-Free Current Patterns to the Ultimate Intrinsic Signal-to-Noise Ratio at Ultra-High Field Strength

      Andreas Pfrommer and Anke Henning

      Version of Record online: 10 FEB 2017 | DOI: 10.1002/nbm.3691

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      We quantitatively compare the ultimate intrinsic SNR obtained with having only curl-free or divergence-free current patterns, with the ultimate intrinsic SNR obtained from a combination of curl-free and divergence-free current patterns. At ultra-high field strength (B0 ≥ 7 T) a combination of curl-free and divergence-free current patterns is required to achieve the best possible SNR at any position in a head-sized sphere. On 1.5- and 3T platforms divergence-free current patterns are sufficient to cover more than 90% of the ultimate intrinsic SNR.

  2. RAPID COMMUNICATIONS

    1. Imaging porcine cardiac substrate selection modulations by glucose, insulin and potassium intervention: A hyperpolarized [1-13C]pyruvate study

      Esben Søvsø Szocska Hansen, Rasmus Stilling Tougaard, Thomas Stokholm Nørlinger, Emmeli Mikkelsen, Per Mose Nielsen, Lotte Bonde Bertelsen, Hans Erik Bøtker, Hans Stødkilde Jørgensen and Christoffer Laustsen

      Version of Record online: 10 FEB 2017 | DOI: 10.1002/nbm.3702

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      Hyperpolarized 13C-pyruvate magnetic resonance imaging was utilized to visualize changes substrate selecting in the porcine heart. By infusion of glucose-potassium-insulin (GIK) the baseline cardiac substrate selection was altered and significant changes in pyruvate-to-bicarbonate and pyruvate-to-lactate was observed. The good reproducibility of this large animal model shows promise for the feasibility of further cardiac studies.

  3. RESEARCH ARTICLES

    1. Brain neurochemical and hemodynamic findings in the NY1DD mouse model of mild sickle cell disease

      Min-Hui Cui, Sandra M. Suzuka, Nicholas A. Branch, Kamalakar Ambadipudi, Sangeetha Thangaswamy, Seetharama A. Acharya, Henny H. Billett and Craig A. Branch

      Version of Record online: 10 FEB 2017 | DOI: 10.1002/nbm.3692

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      Cerebral MRI and MRS in the NY1DD mouse model of mild sickle cell disease were compared with those in the WT mouse. NY1DD mice exhibit elevated cerebral blood flow, N-acetylaspartate (NAA), glutamate, alanine, total creatine and N-acetylaspartylglutamate (NAAG), while glutathione was reduced and correlated negatively with BOLD signal change in response to 100% oxygen and mean diffusivity. NAA + NAAG was inversely related to CBF. These changes suggest a state of chronic oxidative stress leading to compensatory cerebral metabolic adjustments.

    2. Improved multiparametric MRI discrimination between low-risk prostate cancer and benign tissues in a small cohort of 5α-reductase inhibitor treated individuals as compared with an untreated cohort

      Olga Starobinets, John Kurhanewicz and Susan M. Noworolski

      Version of Record online: 6 FEB 2017 | DOI: 10.1002/nbm.3696

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      On multiparametric MRI (mpMRI), a better discrimination between low-grade cancerous and benign regions was observed for prostatic tissues exposed to 5α-reductase inhibitors (5-ARIs) compared with untreated prostatic tissues. Furthermore, a reduction in the coefficient of variation was noted for most of the MR measures in the treated cohort when compared with the untreated group. The findings suggest that pretreatment with 5-ARI may facilitate a better discrimination of low-grade prostate cancer from benign tissues with mpMRI.

    3. Multiparametric CMR imaging of infarct remodeling in a percutaneous reperfused Yucatan mini-pig model

      David Lopez, Jonathan A. Pan, Peter M. Pollak, Samantha Clarke, Christopher M. Kramer, Mark Yeager and Michael Salerno

      Version of Record online: 6 FEB 2017 | DOI: 10.1002/nbm.3693

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      Multiparametric CMR images were obtained from a closed-chest chronic Yucatan mini-pig model of reperfused myocardial infarction at different time points. Acutely there is increased wall thickness at the infarct region (arrows) followed by wall thinning (arrow heads) and ventricular remodeling at later time points. Notably, T2 signal remains elevated throughout the study period and the acute infarct region is not readily identified on native T1 imaging (T1 Pre).

    4. Spatial Hadamard encoding of J-edited spectroscopy using slice-selective editing pulses

      Kimberly L. Chan, Georg Oeltzschner, Michael Schär, Peter B. Barker and Richard A.E. Edden

      Version of Record online: 27 JAN 2017 | DOI: 10.1002/nbm.3688

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      We introduce and perform a comprehensive evaluation a novel technique Spatial Hadamard Editing and Reconstruction for Parallel Acquisition (SHERPA) to simultaneously detect low-concentration metabolites from two separate regions of the human brain by using slice-selective editing pulses during J-difference editing. We demonstrate in spatially-resolved simulations, and phantom and in vivo spectra that the detection of one or more low-concentration metabolites from two brain regions simultaneously is feasible using SHERPA with little loss of signal relative to conventional sequential MEGA-PRESS experiments.

    5. You have full text access to this OnlineOpen article
      On the transmit field inhomogeneity correction of relaxation-compensated amide and NOE CEST effects at 7 T

      Vitaliy Khlebnikov, Johannes Windschuh, Jeroen C.W. Siero, Moritz Zaiss, Peter R. Luijten, Dennis W.J. Klomp and Hans Hoogduin

      Version of Record online: 23 JAN 2017 | DOI: 10.1002/nbm.3687

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      At a B1 of 0.43 μT, a linear B1 correction algorithm sufficiently reduced B1 inhomogeneity effects for both amide and NOE CEST. The image quality produced by the linear correction is similar to that of the interpolation-based B1 correction.

    6. An indirect method for in vivo T2 mapping of [1-13C] pyruvate using hyperpolarized 13C CSI

      Eunhae Joe, Hansol Lee, Joonsung Lee, Seungwook Yang, Young-Suk Choi, Eunkyung Wang, Ho-Taek Song and Dong-Hyun Kim

      Version of Record online: 23 JAN 2017 | DOI: 10.1002/nbm.3690

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      An indirect method for in vivo T2 mapping of 13C–labeled metabolites using T2 and T2* information on water protons obtained a priori is proposed. The T2 of 13C metabolites are inferred using the relationship to T2′ of coexisting 1H and the T2* of 13C metabolites, which is measured using routine hyperpolarized 13C CSI data.

    7. Evaluating kurtosis-based diffusion MRI tissue models for white matter with fiber ball imaging

      Jens H. Jensen, Emilie T. McKinnon, G. Russell Glenn and Joseph A. Helpern

      Version of Record online: 13 JAN 2017 | DOI: 10.1002/nbm.3689

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      The predications from three different diffusion MRI tissue models of white matter for a specific microstructural parameter are compared with an independent measurement obtained with fiber ball imaging (FBI). In regions with high fractional anisotropy (FA), all three models are in good agreement with FBI. However, one of the models is found to perform better for lower FA regions and therefore may have a broader range of applicability.

    8. Towards a neurochemical profile of the amygdala using short-TE 1H magnetic resonance spectroscopy at 3 T

      Florian Schubert, Simone Kühn, Jürgen Gallinat, Ralf Mekle and Bernd Ittermann

      Version of Record online: 6 JAN 2017 | DOI: 10.1002/nbm.3685

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      Short-TE magnetic resonance spectroscopy (MRS) at 3 T was used in combination with a measured macromolecule baseline for spectral fitting and advanced data processing to determine the neurochemical profile in the amygdala in 21 healthy adult subjects. The method permits the determination of concentrations of N-acetylaspartate, total creatine, total choline, myo-inositol and, for the first time, glutamate with high reliability; with lower precision, glutamine and glutathione could also be determined.

  4. Special issue review articles

    1. The clinical utility of QSM: disease diagnosis, medical management, and surgical planning

      Sarah Eskreis-Winkler, Yan Zhang, Jingwei Zhang, Zhe Liu, Alexey Dimov, Ajay Gupta and Yi Wang

      Version of Record online: 1 DEC 2016 | DOI: 10.1002/nbm.3668

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      Quantitative susceptibility mapping (QSM) is an MR technique that depicts and quantifies magnetic susceptibility sources. Mapping iron, the dominant susceptibility source in the brain, has many important clinical applications. Herein, we review QSM clinical applications in the diagnosis, medical management, and surgical treatment of neurological diseases.

    2. Effects of biological tissue structural anisotropy and anisotropy of magnetic susceptibility on the gradient echo MRI signal phase: theoretical background

      Dmitriy A. Yablonskiy and Alexander L. Sukstanskii

      Version of Record online: 11 NOV 2016 | DOI: 10.1002/nbm.3655

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      • The magnetic susceptibility induced MR signal frequency shift δ f  is determined by a magnetic field He outside the inclusions.
      • The field He is different from the macroscopic Maxwell field H (or B).

        inline image

        inline image - the Lorentzian tensor, inline image - the magnetic susceptibility tensor, inline image - the demagnetization tensor depending on the shape of the magnetic susceptibility inclusions.

      • The components of inline image depend on both types of anisotropy: the structural anisotropy of inclusions and the anisotropy of their magnetic susceptibility.

  5. Special issue research articles

    1. Accelerated mapping of magnetic susceptibility using 3D planes-on-a-paddlewheel (POP) EPI at ultra-high field strength

      Daniel Stäb, Steffen Bollmann, Christian Langkammer, Kristian Bredies and Markus Barth

      Version of Record online: 20 OCT 2016 | DOI: 10.1002/nbm.3620

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      Ultra-high field whole brain susceptibility mapping at an isotropic resolution of 1 mm was performed within 39 s using a 3D planes-on-a-paddlewheel (POP) EPI sequence. The non-Cartesian readout scheme is created by rotating a standard EPI readout train around its own phase encoding axis, and provides higher flexibility for echo-time minimization than conventional 3D EPI. Morphologic images, susceptibility maps and values obtained were comparable to those acquired with a conventional 4 min 3D GRE scan.

    2. Heterogeneous anisotropic magnetic susceptibility of the myelin-water layers causes local magnetic field perturbations in axons

      Steffan Puwal, Bradley J. Roth and Peter J. Basser

      Version of Record online: 12 OCT 2016 | DOI: 10.1002/nbm.3628

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      During MRI of neural tissue, microscopic perturbations in the magnetic field are caused by the magnetic susceptibility of myelin. In this paper, analytic expressions for the induced magnetic field distribution and the resulting Larmor frequency shift are derived within and around an axon assuming the myelin susceptibility is anisotropic. These field heterogeneities cause the spins to dephase, shortening T2*. Such measurements could possibly allow the detection of normal and abnormal development, dysmyelination, or demyelination.

    3. In vivo measurement of membrane permeability and myofiber size in human muscle using time-dependent diffusion tensor imaging and the random permeable barrier model

      Els Fieremans, Gregory Lemberskiy, Jelle Veraart, Eric E. Sigmund, Soterios Gyftopoulos and Dmitry S. Novikov

      Version of Record online: 7 OCT 2016 | DOI: 10.1002/nbm.3612

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      The random permeable barrier model (RPBM) provides a novel in vivo method of quantifying myofiber size and membrane permeability from time-dependent diffusion measurements. We describe here the model, details of the stimulated echo DTI acquisition, signal processing, and potential pitfalls. We illustrate the method on pilot examples involving human subjects, revealing RPBM-derived myofiber size increase with training in calf muscle and size decrease with atrophy in shoulder rotator cuff muscle, and comment on the potential clinical relevance of our results.

  6. Special issue review articles

    1. An illustrated comparison of processing methods for phase MRI and QSM: removal of background field contributions from sources outside the region of interest

      Ferdinand Schweser, Simon Daniel Robinson, Ludovic de Rochefort, Wei Li and Kristian Bredies

      Version of Record online: 7 OCT 2016 | DOI: 10.1002/nbm.3604

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      This review article provides insights into theoretical similarities between background correction techniques and resolves fundamental and hitherto open questions related to background field correction in MRI phase imaging. A comprehensive quantitative comparison of published techniques was performed that illustrates benefits and limitations of the techniques.

  7. Special issue research articles

    1. Structural and functional quantitative susceptibility mapping from standard fMRI studies

      H. Sun, P. Seres and A.H. Wilman

      Version of Record online: 30 SEP 2016 | DOI: 10.1002/nbm.3619

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      Structural deep grey matter quantitative susceptibility maps can be extracted from regular fMRI studies, which may enable increased study of iron accumulation in healthy aging and disease within existing BOLD fMRI studies with no additional acquisitions required.

  8. Special issue review articles

    1. You have full text access to this OnlineOpen article
      An illustrated comparison of processing methods for MR phase imaging and QSM: combining array coil signals and phase unwrapping

      Simon Daniel Robinson, Kristian Bredies, Diana Khabipova, Barbara Dymerska, José P. Marques and Ferdinand Schweser

      Version of Record online: 13 SEP 2016 | DOI: 10.1002/nbm.3601

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      Phase data from array coils can be combined using the Roemer method at UHF using an inhomogeneous transmit-receive coil, but this introduces transmit phase into the combined image. The most effective alternative approaches assessed were the Virtual Receiver Coil and short echo-time reference scan (COMPOSER) methods. Spatial unwrapping was found to be fragile in the presence of rapid phase fluctuations, while faster temporal unwrapping was more prone to errors at low SNR. Laplacian unwrapping was both fast and effective.

    2. Diffusion MRI of the spinal cord: from structural studies to pathology

      Yoram Cohen, Debbie Anaby and Darya Morozov

      Version of Record online: 6 SEP 2016 | DOI: 10.1002/nbm.3592

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      The spinal cord is amenable to ex vivo diffusion MRI microscopy but in vivo diffusion MRI of this organ is quite challenging. This review describes recent developments in the applications of diffusion MRI of the spinal cord with some emphasis on diffusion methods beyond the tensor. After a brief survey of the available diffusion MRI methodologies, selected applications ranging from microstructural studies to studies of selected pathologies are presented.

    3. Overview of quantitative susceptibility mapping

      Andreas Deistung, Ferdinand Schweser and Jürgen R. Reichenbach

      Version of Record online: 19 JUL 2016 | DOI: 10.1002/nbm.3569

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      In this article, we review the theoretical basics of quantitative susceptibility mapping (QSM) and susceptibility tensor imaging and briefly summarize the computational strategies for the characterization of magnetic susceptibility with MRI phase. In addition, we provide an overview of current methodological and clinical applications of QSM with a focus on brain imaging.

  9. Special issue research articles

    1. Single-step quantitative susceptibility mapping with variational penalties

      Itthi Chatnuntawech, Patrick McDaniel, Stephen F. Cauley, Borjan A. Gagoski, Christian Langkammer, Adrian Martin, P. Ellen Grant, Lawrence L. Wald, Kawin Setsompop, Elfar Adalsteinsson and Berkin Bilgic

      Version of Record online: 22 JUN 2016 | DOI: 10.1002/nbm.3570

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      The tissue susceptibility distribution is directly estimated from the raw phase of a gradient echo acquisition by solving total variation (TV) and total generalized variation (TGV) regularized optimization problems. Efficient algorithms for the proposed single-step quantitative susceptibility mapping (QSM) reconstructions, which permit analytical solutions to all the subproblems, are developed based on the alternating direction method of multipliers (ADMM). A dramatic reduction in dipole streaking artifacts and improved homogeneity of image contrast over conventional QSM are demonstrated using numerical simulations and in vivo experiments that were acquired using signal-to-noise ratio (SNR)-efficient acquisitions including multi-echo Wave-CAIPI (controlled aliasing in parallel imaging) and three-dimensional echo planar imaging (3D EPI).

    2. A comprehensive numerical analysis of background phase correction with V-SHARP

      Pinar Senay Özbay, Andreas Deistung, Xiang Feng, Daniel Nanz, Jürgen Rainer Reichenbach and Ferdinand Schweser

      Version of Record online: 3 JUN 2016 | DOI: 10.1002/nbm.3550

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      We propose a new V-SHARP scheme, with optimal and generalized parameters, based on a high-pass filtering approach. The local root-mean-square error (RMSE) between the results from V-SHARP and the ground-truth, background-corrected field map decreased as the center of the brain was approached. The optimal susceptibility maps were calculated for a radius between 6 and 10 mm and a regularization parameter between 0 and 0.01 mm−1. With the novel scheme, the regularization parameter is independent of other imaging parameters, such as the image resolution.

  10. Special issue review articles

    1. Skeletal muscle diffusion tensor-MRI fiber tracking: rationale, data acquisition and analysis methods, applications and future directions

      Bruce M. Damon, Martijn Froeling, Amanda K. W. Buck, Jos Oudeman, Zhaohua Ding, Aart J. Nederveen, Emily C. Bush and Gustav J. Strijkers

      Version of Record online: 3 JUN 2016 | DOI: 10.1002/nbm.3563

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      A muscle's abilities to generate force and actuate movement are influenced, in part, by the arrangement of fibers with respect to the muscle's mechanical line of action. We describe the use of diffusion tensor-MRI (DT-MRI) muscle fiber tracking for the study of this structure. We discuss the importance of muscle structure to muscle function, describe DT-MRI's application to muscle, discuss issues related to data acquisition and analysis, show how DT-MRI has provided new insights into muscle function and highlight future research directions.

    2. Contributions to magnetic susceptibility of brain tissue

      Jeff H. Duyn and John Schenck

      Version of Record online: 30 MAY 2016 | DOI: 10.1002/nbm.3546

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      In human brain, iron and myelin are major contributors to MRI magnetic susceptibility contrast. Both their concentration, as well as their microscropic distribution, determine the strength of their contribution. Inferring concentrations from susceptibility weighted MRI requires conjoint analysis of both amplitude and phase of the signal decay curve, and simplifying assumptions about the contrast mechanism.

    3. Computational methods for image reconstruction

      Julianne Chung and Lars Ruthotto

      Version of Record online: 26 MAY 2016 | DOI: 10.1002/nbm.3545

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      We review analytical tools and state-of-the-art computational tools for solving image reconstruction problems. By comparing quantitative susceptibility mapping (QSM) with the classic image-deblurring problem, we show that a severe challenge for QSM reconstruction is to distinguish between noise and signal contributions in the data; therefore regularization methods are crucial. We survey some regularization approaches and regularization parameter selection methods and discuss efficient numerical implementations for large-scale QSM problems.

  11. Special issue research articles

    1. Determination of detection sensitivity for cerebral microbleeds using susceptibility-weighted imaging

      Sagar Buch, Yu-Chung N. Cheng, Jiani Hu, Saifeng Liu, John Beaver, Rajasimhan Rajagovindan and E. Mark Haacke

      Version of Record online: 20 MAY 2016 | DOI: 10.1002/nbm.3551

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      A direct formulaic approach is proposed that uses spherical simulations to estimate the underlying size of a cerebral microbleed (CMB) based on the number of radiologically detected voxels, the estimated susceptibility and acquisition parameters. A comparison between measured values and values derived from our formulae for the prediction of the number of voxels detected due to the blooming effect for CMBs with diameters of 2 voxels (a, b) and 1 voxel (c, d). Signal-to-noise ratio (SNR) values are 47 : 1 for 7-T, 20 : 1 for 3-T and 10 : 1 for 1.5-T simulations, is shown in the Figure.

  12. Special issue review articles

    1. Susceptibility-weighted imaging: current status and future directions

      Saifeng Liu, Sagar Buch, Yongsheng Chen, Hyun-Seok Choi, Yongming Dai, Charbel Habib, Jiani Hu, Joon-Yong Jung, Yu Luo, David Utriainen, Meiyun Wang, Dongmei Wu, Shuang Xia and E. Mark Haacke

      Version of Record online: 18 MAY 2016 | DOI: 10.1002/nbm.3552

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      Susceptibility-weighted imaging (SWI) is a method that uses the intrinsic nature of local magnetic fields to enhance image contrast in order to improve the visibility of various susceptibility sources and to facilitate diagnostic interpretation. In this article, we review the basics of SWI, with discussions on data acquisition, reconstruction and post-processing. In addition, we show a few clinical applications of SWI, such as the imaging of stroke, traumatic brain injury, the carotid vessel wall and siderotic nodules in cirrhotic liver.

  13. Special issue research articles

    1. Dentate nucleus iron deposition is a potential biomarker for tremor-dominant Parkinson's disease

      Naying He, Pei Huang, Huawei Ling, Jason Langley, Chunlei Liu, Bei Ding, Juan Huang, Hongmin Xu, Yong Zhang, Zhongping Zhang, Xiaoping Hu, Shengdi Chen and Fuhua Yan

      Version of Record online: 18 MAY 2016 | DOI: 10.1002/nbm.3554

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      The tremor-dominant (TD) Parkinson's disease group showed increased susceptibility in the bilateral dentate nucleus (DN) compared with the healthy control group. No difference was seen in R2* between the TD group and healthy control group, indicating that the deposited iron in DN may comprise smaller iron particles. The DN susceptibility in drug-naive PD patients was positively correlated with tremor score. These findings indicate that iron load within DN may make an important contribution to motor phenotypes in PD.

  14. Special issue review articles

    1. Magnetic susceptibility anisotropy outside the central nervous system

      Russell Dibb, Luke Xie, Hongjiang Wei and Chunlei Liu

      Version of Record online: 16 MAY 2016 | DOI: 10.1002/nbm.3544

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      Magnetic susceptibility anisotropy is observed in tissues throughout the body and arises from a variety of organized molecular sources including the epithelial lipids in the kidney, myofilament proteins in the heart, and collagen fibrils in connective tissue. Two MRI tools, susceptibility tensor imaging and quantitative susceptibility mapping, have exploited this anisotropy to assess the microstructure and orientation of renal tubules, myofibers, and articular cartilage. Measuring susceptibility anisotropy using MRI is a promising technique for studying healthy and diseased organ tissues.

  15. Special issue research articles

    1. MR phase imaging with bipolar acquisition

      Joseph Dagher and Kambiz Nael

      Version of Record online: 5 MAY 2016 | DOI: 10.1002/nbm.3523

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      Bipolar (non-yback) multi-echo readouts offer significant SNR advantages over monopolar echo readouts, but introduce unknown phase errors. We present a novel MR phase-imaging method that jointly disambiguates errors from bipolar readouts as well as errors from phase wrapping, phase noise and channel-dependent phase offsets. The approach, based on voxel-per-voxel maximum-likelihood estimation, enables MR phase imaging in SNR-limited scenarios, such as at in-plane resolutions of 310 µm at 3 T.

  16. Special issue review articles

    1. Iron quantification with susceptibility

      Stefan Ropele and Christian Langkammer

      Version of Record online: 27 APR 2016 | DOI: 10.1002/nbm.3534

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      Iron in tissue can cause local and non-local changes of the magnetic field, which strongly depend on the spin state and valence of its electrons in the iron compound. Quantitative susceptibility mapping allows to assess the iron content and typically shows a good linear relationship with iron concentration. Larger uncertainties may arise in myelinated fibers and in the presence of mineralized iron with unknown magnetic phases such as hemosiderin or hemozoin.

    2. Susceptibility tensor imaging (STI) of the brain

      Wei Li, Chunlei Liu, Timothy Q. Duong, Peter C. M. van Zijl and Xu Li

      Version of Record online: 27 APR 2016 | DOI: 10.1002/nbm.3540

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      Susceptibility tensor imaging (STI) is a recently developed MRI technique that allows quantitative determination of orientation-independent magnetic susceptibility parameters from gradient echo signal phase. By modeling the magnetic susceptibility of each voxel as a symmetric rank-2 tensor, individual magnetic susceptibility tensor elements as well as the magnetic susceptibility anisotropy (MSA) can be determined for brain tissues. Similar to diffusion tensor imaging (DTI), STI allows mapping of brain white matter fiber orientations and reconstruction of 3D white matter pathways using the principal eigenvectors of the susceptibility tensor.

  17. Special issue research articles

    1. Investigating lipids as a source of chemical exchange-induced MRI frequency shifts

      K. Shmueli, S. J. Dodd, P. van Gelderen and J. H. Duyn

      Version of Record online: 13 APR 2016 | DOI: 10.1002/nbm.3525

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      We measured exchange-induced frequency shifts (fe) in a model of cell membranes consisting of multilamellar vesicles of cerebrosides and phospholipids. Using chemical shift imaging, with dioxane as an internal reference to remove susceptibility-induced frequency shifts, we found significant increases in fe with increasing lipid concentration: 0.044 ± 0.008 ppb/mM (r2 = 0.877, p < 0.01). We also measured and corrected for the water–dioxane frequency shift which was –0.021 ± 0.002 ppb/mM dioxane in agreement with previous measurements at low dioxane concentrations.

  18. Special issue review articles

    1. Mechanisms of T2* anisotropy and gradient echo myelin water imaging

      Jongho Lee, Yoonho Nam, Joon Yul Choi, Eung Yeop Kim, Se-Hong Oh and Dong-Hyun Kim

      Version of Record online: 7 APR 2016 | DOI: 10.1002/nbm.3513

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      A white matter voxel demonstrates T2* anisotropy that originates from isotropic and anisotropic magnetic susceptibility and multi-compartmental microstructure induced frequency shifts. These mechanisms result in multi-exponential magnitude decay and nonlinear phase evolution. Using the complex signal, myelin water fraction can be estimated, producing gradient echo myelin water imaging.

    2. Susceptibility-based time-resolved whole-organ and regional tissue oximetry

      Felix W. Wehrli, Audrey P. Fan, Zachary B. Rodgers, Erin K. Englund and Michael C. Langham

      Version of Record online: 26 FEB 2016 | DOI: 10.1002/nbm.3495

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      Quantification of reactive hyperemia with dynamic oximetry showing cross-sectional phase difference image of the thigh, 10 cm below the inferior boundary of the pressure cuff along with post-ischemia femoral vein SvO2 time course, and series of zoomed phase images showing relative phase of venous blood during period indicated. Darker blue represents lower saturation levels. Parameterization of time-course data yields quantitative metrics: washout time, upslope and overshoot.

  19. Special issue research articles

    1. Reproducibility of R2* and quantitative susceptibility mapping (QSM) reconstruction methods in the basal ganglia of healthy subjects

      M. D. Santin, M. Didier, R. Valabrègue, L. Yahia Cherif, D. García-Lorenzo, P. Loureiro de Sousa, E. Bardinet and S. Lehéricy

      Version of Record online: 23 FEB 2016 | DOI: 10.1002/nbm.3491

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      The registration of four sessions of three-dimensional gradient echo complex images in a cohort of healthy subjects allowed the quantification of the reproducibility of quantitative susceptibility mapping (QSM) methods versus the reproducibility of more conventional R2* mapping. The sensitivity to changes in the QSM technique was shown to reach a level of 1.5% in the basal ganglia.

    2. Joint 2D and 3D phase processing for quantitative susceptibility mapping: application to 2D echo-planar imaging

      Hongjiang Wei, Yuyao Zhang, Eric Gibbs, Nan-Kuei Chen, Nian Wang and Chunlei Liu

      Version of Record online: 17 FEB 2016 | DOI: 10.1002/nbm.3501

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      Current two-dimensional (2D) echo-planar imaging (EPI)-based quantitative susceptibility mapping (QSM) uses three-dimensional (3D) phase unwrapping followed by 3D background phase removal, and leaves phase inconsistencies across slices. Here, we report a new data processing procedure that integrates 2D and 3D phase processing to reduce phase inconsistencies between slices. Experimental results show that the new 2D EPI-based QSM method can produce quantitative susceptibility measures that are comparable with those of time-consuming 3D gradient-echo (GRE)-based QSM.

    3. Quantitative susceptibility mapping at 3 T: comparison of acquisition methodologies

      M. Louis Lauzon, Cheryl R. McCreary, D. Adam McLean, Marina Salluzzi and Richard Frayne

      Version of Record online: 17 FEB 2016 | DOI: 10.1002/nbm.3492

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      We compared deep grey matter susceptibility (χ) values in healthy adults acquired from various quantitative susceptibility mapping (QSM) sequences at 3 T using unipolar or bipolar readout gradients, accelerated imaging or not (R2 or R1), with/without gradient-warp correction (GW). Using a linear mixed effects model, only GW was found to alter the χ estimate, but its overall effect was small (~5%).

    4. Regionally progressive accumulation of iron in Parkinson's disease as measured by quantitative susceptibility mapping

      Xiaojun Guan, Min Xuan, Quanquan Gu, Peiyu Huang, Chunlei Liu, Nian Wang, Xiaojun Xu, Wei Luo and Minming Zhang

      Version of Record online: 8 FEB 2016 | DOI: 10.1002/nbm.3489

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      Quantitative susceptibility mapping was used to confirm a regionally progressive pattern of iron accumulation in patients with Parkinson's disease (PD) at different stages, which indicates that iron deposition in the substantia nigra pars compacta (SNc) is affected exclusively in the early PD (EPD) patients, while the substantia nigra pars reticulata (SNr), red nucleus (RN) and globus pallidus internal (GPi) as well as globus pallidus external (GPe) become involved in the late PD (LPD) patients.

  20. Special issue review articles

    1. In vivo diffusion MRS investigation of non-water molecules in biological tissues

      Peng Cao and Ed X. Wu

      Version of Record online: 21 JAN 2016 | DOI: 10.1002/nbm.3481

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      In this review, recent diffusion MRS studies of biologically relevant non-water molecules under normal and diseased conditions will be presented. Technique considerations for diffusion MRS experiments will be discussed. With advances in MRI hardware and diffusion methodology, diffusion MRS of non-water molecules is expected to provide increasingly valuable and biologically specific information on tissue microstructures and physiology, complementing the traditional diffusion MR of small and ubiquitous water molecules.

    2. Diffusion MRI in early cancer therapeutic response assessment

      C. J. Galbán, B. A. Hoff, T. L. Chenevert and B. D. Ross

      Version of Record online: 15 JAN 2016 | DOI: 10.1002/nbm.3458

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      Diffusion-weighted MRI (DW-MRI) is sensitive to cellular changes and has been evaluated extensively as a quantitative and early imaging biomarker of the therapeutic response. DW-MR can be applied to many different solid tumors to detect changes in cellularity as measured by an early increase in the apparent diffusion coefficient (ADC) of water molecules within the lesion. An overview of DW-MRI acquisition protocols, quantitative image analysis approaches and applications implementing DW-MRI for the early prediction of cancer treatment response is presented.

    3. Diffusion lung imaging with hyperpolarized gas MRI

      Dmitriy A. Yablonskiy, Alexander L. Sukstanskii and James D. Quirk

      Version of Record online: 16 DEC 2015 | DOI: 10.1002/nbm.3448

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      Diffusion MRI with hyperpolarized gases provides quantitative information on lung microstructure at the alveolar level and makes it possible to measure the same morphometric parameters (mean linear intercept, surface-to-volume ratio, number of alveoli per unit volume) as have been traditionally obtained by means of invasive stereology.

    4. Diffusion tensor imaging in abdominal organs

      Rotem Shlomo Lanzman and Hans-Jörg Wittsack

      Version of Record online: 11 NOV 2015 | DOI: 10.1002/nbm.3434

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      Diffusion tensor imaging of abdominal organs adds additional diagnostic information about the microstructure of human tissues. Besides the technical requirements for DTI in abdominal organs, recent studies of major organs such as kidney, liver, prostate and pelvic floor are presented and discussed.

    5. You have full text access to this OnlineOpen article
      Diffusion MRI in the heart

      Choukri Mekkaoui, Timothy G. Reese, Marcel P. Jackowski, Himanshu Bhat and David E. Sosnovik

      Version of Record online: 20 OCT 2015 | DOI: 10.1002/nbm.3426

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      Diffusion MRI provides unique information on the integrity of the myocardium without the need for exogenous contrast agents. However, diffusion MRI in the heart has proven technically challenging. In this review, we describe approaches that have been developed to overcome these challenges, and briefly examine the application of diffusion MRI in ischemic heart disease. The use of diffusion MRI as a clinical tool may lead to new and complementary approaches to diagnose and treat patients with heart disease.

    6. Diffusion imaging of the vertebral bone marrow

      Olaf Dietrich, Tobias Geith, Maximilian F. Reiser and Andrea Baur-Melnyk

      Version of Record online: 26 JUN 2015 | DOI: 10.1002/nbm.3333

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      Diffusion-weighted MRI (DWI) of the vertebral bone marrow is a clinically important tool for the characterization of bone-marrow pathologies and, in particular, for the differentiation of benign and malignant vertebral compression fractures. DWI of the vertebral bone marrow is, however, complicated by some unique MR and tissue properties of vertebral bone marrow. This review summarizes data from numerous studies in which diffusion measurements of normal vertebral bone marrow and of different vertebral bone-marrow lesions were performed.

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