Diego Hernando¹, Naila Qazi¹, and Scott B. Reeder^1,2
1Radiology, University of Wisconsin-Madison, Madison, WI, United States, ²Medical Physics, University of Wisconsin-Madison, Madison, WI, United States

Measurement of liver iron concentration (LIC) is needed for detection and treatment monitoring of iron overload. R2-based techniques (eg: Ferriscan) are accurate at 1.5T, however they require long acquisition times. R2*-based techniques are fast, but suffer from several confounding factors: liver fat, background B0 variations and noise floor effects. In this work, we calibrated confounder-corrected R2*-based LIC quantification at 1.5T and 3T using multiple different protocols, with Ferriscan-LIC (1.5T) as reference standard. Nearly identical calibrations were obtained with different protocols at each field strength, suggesting that R2* may provide accurate and robust LIC quantification if relevant confounding factors are addressed.

Chih-Ching Lai¹ and Fu-Nien Wang^1
1Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan

Iron (Fe) and copper (Cu) are essential elements important for metabolism and biochemical functions in brain. In this study, we design a phantom experiment to investigate whether the relaxation rates of Fe and Cu solutions could be modeled as a linear combining relationship. We observed that the relaxation rates of Fe²⁺ and Cu²⁺ mixed solutions could be predicted successfully by measuring R₁ and R₂ of Fe²⁺ and Cu²⁺ solutions respectively. However, the nonlinear R₁ and R₂ of Fe³⁺ were improper for linear model. Care should be taken as using relaxometry to represent the concentration of metal ions.

Antonella Meloni¹, Hugh Young Rienhoff², Amber Jones², Aessia Pepe¹, Massimo Lombardi¹, and John C. Wood^3
1CMR Unit, Fondazione G. Monasterio CNR-Regione Toscana and Institute of Clinical Physiology, Pisa, Italy, ²FerroKin BioSciences, Inc, San Carlo, California, United States, ³Division of Cardiology, Children’s Hospital Los Angeles, Los Angeles, California, United States

R2* values vary with post-processing method but yield statistically identical LIC values when technique-appropriate calibration curves are used. In the literature, R2* values should be converted into LIC values to facilitate comparisons across studies.

Takeshi Yokoo^1,2, Qing Yuan¹, and Ivan E. Dimitrov^2,3
1Radiology, UT Southwestern Medical Center, Dallas, TX, United States, ²Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, United States, ³Philips Medical Systems, Highland Heights, OH, United States

Various strategies for T2* mapping for liver iron quantification in the presence of noise is investigated in this study, including log-linear and nonlinear curve fitting, either using magnitude or complex signal data.

Ruitian Song¹, Travis Bevington¹, Brian Allen Taylor¹, Axel J. Krafft¹, Ralf B. Loeffler¹, and Claudia M. Hillenbrand^1
1Radiological Sciences, St Jude Children's Research Hospital, Memphis, Tennessee, United States

T2* measurement accuracy can be impacted by macroscopic field inhomogeneities (i.e., background gradients) that are introduced by susceptibility changes. Two major methods have been proposed to correct for the errors in T2*-quantification that arise from these background gradients: sinc-weighted fitting of the signal decay (FIT) and direct measurement of the magnetic field (DMF). These two methods are compared and evaluated via phantom and volunteer tests. We conclude that FIT is preferred unless the z component of the magnetic field dominates among the three spatial components.

Rik P.M. Moonen¹, Pieternel van der Tol¹, Stefanie J.C.G. Hectors¹, Klaas Nicolay¹, and Gustav J. Strijkers^1
1Biomedical Engineering/ Biomedical NMR, Eindhoven University of Technology, Eindhoven, Netherlands

In this in vitro study we show that T_1ρ provides enhanced sensitivity for the detection of SPIO and USPIO contrast agents in comparison to T₂. ΔR_1ρ values at 1.41 T of agar gels containing different concentrations of Sinerem and Resovist were respectively up to 4.8-fold and 6.6-fold higher as compared to ΔR₂.

Md Nasir Uddin¹, R. Marc Lebel¹, and Alan H. Wilman^1
1Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada

Transverse relaxometry at multiple field strengths may provide increased iron specificity using field dependent relaxation increase (FDRI). We compared high field (4.7 T) transverse relaxometry to single and multislice FDRI using 1. 5 T and 4.7 T. Results for iron-rich subcortical grey matter demonstrate the value of high field measurement, with only slight improvement using FDRI.

Meiyan Feng¹, Huashuai Gao¹, Xinyuan Zhang¹, Yanqiu Feng¹, Wufan Chen¹, Xuegang Xin¹, and Taigang He^2,3
1School of Biomedical Engineering, Southern Medical University, Guangzhou, China, ²Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom,³National Heart and Lung Institute, Imperial College, London, United Kingdom

The whole liver ROI method for R2* measurement has been shown better reproducibility than the routinely used mROI method, but still suffers from noise, partial volume effect and subjective segmentation of liver parenchyma and vessels. We proposed an automatic parenchyma extraction (APE) method of R2* measurement, the measurement accuracy of which was evaluated in both simulation and patient studies. The mean R2* evaluation error percentage and the coefficient of variation (CoV) of inter-observer reproducibility for the APE method severally were 0.34% and 1.39%. The proposed APE method may be important for increasing the diagnostic confidence of R2* measurement.

Houshang Amiri^1,2, Morteza Mahmoudi^3,4, Jolanda de Vries², Arend Heerschap¹, and Alessandro Lascialfari^5
1Radiology Department, Radboud University Nijmegen Medical Centre, Nijmegen, Gelderland, Netherlands, ²Tumor Immunology Department, Nijmegen Centre for Molecular Life Sciences, Nijmegen, Gelderland, Netherlands, ³Nanotechnology Research Centre, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Tehran, Iran, ⁴Pasteur Institute of Iran, Tehran, Tehran, Iran, ⁵Physics Department, Milan University, Milan, Lombardia, Italy

To investigate the effects of a protein corona (PC) on MRI contrast efficiency of superparamagnetic iron oxide NPs (SPIONs), we synthesized two series of SPIONs with various thickness and functional groups of the dextran surface coating. 1H longitudinal and transverse relaxivities of the SPIONs as a function of the Larmor frequency were obtained. Transverse relaxivity was dependent on the functional group of the SPIONs. The presence of the PC did slightly increased the relaxivity of the negatively charged SPIONs and dramatically decreased it for positively charged ones. in vitro MRI experiments at were in full agreement with the relaxometry findings.

Jan Sedlacik¹, Jürgen R. Reichenbach², and Ferdinand Schweser^2
1Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, ²Medical Physics Group, Institute of Diagnostic and Interventional Radiology I, University Hospital-Friedrich Schiller University Jena, Jena, Germany

Due to diffusion effects, the transverse relaxivity caused by small iron particles depends on the particles’ size. Consequently, the same amount of iron can cause very different relaxation rates for particles of different size compromising relaxation-based iron quantification measurements. However, the bulk frequency shift is supposed to be determined by the average magnetic susceptibility of the solution and, therefore, independent of particle size, aggregation or distribution. The purpose of this work was to investigate this theoretical behavior in a phantom experiment and to discuss implications for future in vivo studies.

Naila Qazi¹, Scott B. Reeder^1,2, and Diego Hernando^1
1Radiology, University of Wisconsin-Madison, Madison, WI, United States, ²Medical Physics, University of Wisconsin-Madison, Madison, WI, United States

R2*-MRI has the potential to provide rapid and accurate iron quantification. However, the robustness of liver R2* mapping to variations in imaging parameters is unknown. Indeed, lack of robustness is the main criticism of R2* mapping, currently precluding it from becoming widely accepted for iron quantification. In this work, we demonstrate that liver R2* mapping in patients with liver iron overload can be performed with excellent robustness to variations in spatial resolution, slice orientation and echo time combination at both 1.5T and 3T.

Christian Langkammer¹, Nikolaus Krebs², Walter Goessler³, Eva Scheurer², Franz Fazekas¹, and Stefan Ropele^1
1Department of Neurology, Medical University of Graz, Graz, Austria, ²Ludwig Boltzmann Institute for Clinical-Forensic Imaging, Graz, Austria, ³Institute of Analytical Chemistry, University of Graz, Graz, Austria

This study provides regional reference values for iron concentrations in the corpus callosum and demonstrates a heterogeneous distribution along the corpus callosum. These variations substantially impact R2* and, thus, will consequently impact also phase and bulk susceptibility.

Eamon Doyle¹, Nilesh R. Ghugre², Krishna S. Nayak³, and John Wood^4
1University of Southern California, Los Angeles, CA, United States, ²Imaging Research, Sunnybrook Health Sciences Centre, Toronto, ON, Canada, ³Electrical Engineering, University of Southern California, Los Angeles, CA, United States, ⁴Cardiology, Children's Hospital of Los Angeles, Los Angeles, CA, United States

Monte Carlo simulation of iron-loaded liver tissue indicates that B1+ inhomogeneity may lead to inaccurate iron quantification due to increased R2 value estimates.

Junyu Guo¹, Qing Ji¹, and Wilburn E. Reddick^1
1Division of Translational Imaging Research, St Jude Children Research Hospital, Memphis, TN, United States

Myelin water imaging is a promising technique for evaluating white matter diseases. Poor image quality and a long acquisition time are major obstacles to practical clinical applications. In this study, a novel postprocessing method with an efficient multi-slice acquisition scheme, called T2 spectrum analysis using a weighted regularized non-negative least squares algorithm and non-local mean filter (T2SPARC), is presented to overcome these obstacles. In vivo results from healthy volunteers and a patient with leukoencephalopathy showed that the T2SPARC method can generate robust and high-quality myelin water fraction (MWF) maps of 10 slices within 11 minutes.

Christian Labadie¹, Monique Aubert-Frécon¹, Stefan Hetzer², and Harald E. Möller^3
1Laboratoire de Spectrométrie Ionique et Moléculaire, Université Claude Bernard, Lyon, France, ²Bernstein Center for Computational Neuroscience, Berlin, Germany, ³Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

We propose a method to coherently combine phase-array using coil sensivitivities estimated in place from a phased Look-Locker inversion recovery. Additionally we investigate the effect of the range of the geometrically sampled inversion times (TI) on the estimation of the T1 based MWF at 3T.

Junyu Guo¹ and Wilburn E. Reddick^1
1Division of Translational Imaging Research, St Jude Children Research Hospital, Memphis, TN, United States

Myelin water imaging is a promising, noninvasive technique for evaluating white matter diseases. Myelin water fraction (MWF) can serve as a direct indicator of myelin component change due to white matter diseases. To calculate MWF, the weighted regularized non-negative least squares (wrNNLS) algorithm with a large regularization coefficient was used to balance the sensitivity and reliability to measure MWF values. In this study, simulations were performed to compare the regularization of wrNNLS with the regularized non-negative least squares (rNNLS) algorithm and validate the large empirical selected regularization coefficient for wrNNLS due to imperfect refocusing pulses.

John M. Ollinger¹, Samuel A. Hurley², Andrew L. Alexander³, and Gerard Riedy^4
1NICoE, Walter Reed National Military Medical Center, Bethesda, Maryland, United States, ²Medical Physics, University of Wisconsin-Madison, Madison, WI, United States, ³Medical Physics, University of Wisconsin, Madison, WI, United States, ⁴NICoE, Walter Reed National Military Medical Center, Bethesda, MD, United States

The parameters of the two-compartment mcDESPOT model for myelin water fraction are estimated with a non-linear least-squares algorithm constrained by a uniform prior. Combined with improved flip angle calibration, flip angle selection, and phase-cycling angles, the method yields estimates of myelin water fraction of visually high quality. However, estimates of myelin T1 and myelin residence time were strongly dependent on the choice of constraint and starting values. Quantitative values of myelin water fraction depended on these values as well as the parameterization of the model. This suggests that myelin water fraction images may represent a combination of physiological parameters.

Philipp Krämer¹ and Lothar R. Schad^1
1Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany

3D spin-echo and turbo-spin-echo T₂ weighted imaging suffers from high acquisition duration because of the necessary long repetition times. For 2D cardiac T₂ measurement a sequence was proposed which applies two 90° rectangular pulses and a Malcolm-Levitt composite pulse train of four 180° refocusing pulses for T₂ weightening prior to imaging. In this work, the same T₂ preparation method is combined with a fast 3D TrueFISP imaging sequence enabling fast 3D T₂ measurement.

Cihat Eldeniz¹, Weili Lin^1,2, and Hongyu An^2
1Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States, ²Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States

Fast and accurate T1 mapping can be useful in many ways. T-One With Enhanced Robustness and Speed [TOWERS] is a new EPI-based sequence that can acquire enough data for the T1 mapping of the whole brain in less than 2 minutes and a half. It has two segments which are independent of each other in terms of spin history, making it robust to motion in any of the two segments.

Thomas Benkert¹, Martin Ott¹, Riad Ababneh², Martin Blaimer¹, Peter M. Jakob^1,3, and Felix A. Breuer^1
1Research Center Magnetic Resonance Bavaria, Würzburg, Bavaria, Germany, ²Yarmouk University, Irbid, Jordan, ³Experimental Physics 5, University Würzburg, Würzburg, Bavaria, Germany

A phase cycled bSSFP sequence with a multi-echo readout is proposed to achieve T1,T2 and PD maps as well as robust fat-water separation without any banding artifacts due to offresonances with just one single sequence.

Hidehiro Watanabe¹, Nobuhiro Takaya¹, and Fumiyuki Mitsumori^1
1Center for Environmental Measurement and Analysis, National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan

3D MASE method for whole brain T₂ mapping with high accuracy was developed at 4.7T. This has a feature of accurate 3D T₂ mapping by a precise slice selection with a pair of adiabatic pulses for the refocusing slice selection. After magnetization decayed purely by T₂ is generated by a multi-pulse adiabatic spin echo sequence, it is flipped back to the longitudinal magnetization by a flipback adiabatic pulse. Then, signal is accumulated by the 3D Turbo-Flash imaging. In human brain measurements, T₂ values were in good agreement with those by the conventional 2D MASE method.

Casey P. Johnson¹, Daniel R. Thedens¹, and Vincent A. Magnotta^1,2
1Radiology, University of Iowa, Iowa City, IA, United States, ²Psychiatry, University of Iowa, Iowa City, IA, United States

Acceleration methods are assessed for 3D T1rho mapping of the brain. It is demonstrated that substantial reductions in acquisition time (R>5) can be realized while largely retaining T1rho contrast detectability. The use of only two vs. four spin-lock times is also shown to be highly effective, particularly when combined with high degrees of undersampling, yielding net sampling reductions of R>10. The methods demonstrated in this work may greatly improve the utility of 3D T1rho mapping of brain diseases such as Alzheimer’s and Parkinson’s while also enabling state-based dynamic imaging studies such as investigations of stimulus-induced T1rho-sensitive pH fluctuations.

Cheng-Chieh Cheng^1,2, Tzu-Cheng Chao³, Hsiao-Wen Chung¹, Lawrence P. Panych², and Bruno Madore^2
1Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan, ²Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States, ³Department of Computer Science and Information Engineering, National Cheng-Kung University, Tainan, Taiwan

Brain iron accumulation may be related to various neurological diseases such as Parkinson’s disease, Alzheimer’s disease, and multiple sclerosis. Quantitative MR techniques, such as MR relaxometry and susceptibility mapping can be helpful toward quantifying brain iron content. A novel approach is proposed that can simultaneously measure T2, T2* and susceptibility-induced internal field perturbations from the same rapid scan. It is hoped that the present method may prove a useful tool toward investigating conditions linked with elevated brain iron content.

Peter J. Ross¹, Lionel M. Broche¹, Kerrin J. Pine¹, and David J. Lurie^1
1Aberdeen Biomedical Imaging Centre, University of Aberdeen, Aberdeen, Scotland, United Kingdom

Fast Field-Cycling (FFC) adds a new dimension to MRI by rapidly switching B₀ between levels during a pulse sequence. In this way it is possible to observe the variation of tissue T₁ with field strength. Relaxometric FFC imaging collects data for T₁ images at a range of field strengths, but is inherently time-consuming. We have greatly increased the speed of acquisition by collecting only one inversion-recovery image per field and by implementing an FFC Fast Spin-Echo sequence. Typical acquisition time is 30 min for a set of T₁images at 22 field strengths, making volunteer or clinical studies feasible.

Yuegao Huang^1,2, Daniel Coman^1,2, Garry E. Kiefer³, Sara Samuel⁴, and Fahmeed Hyder^1,4
1Diagnostic Radiology, Yale University, New Haven, CT, United States, ²Magnetic Resonance Research Center, Yale University, New Haven, CT, United States, ³Macrocyclics, Dallas, TX, United States, ⁴Biomedical Engineering, Yale University, New Haven, CT, United States

A cocktail of PARACEST agents, each sensitive to an independent parameter, is believed to allow multi-parametric detection. But the multiple-pool proton exchange situation is not a linear combination of two-pool exchange models. To enable multivalent imaging for a cocktail of PARACEST agents, we posited that because PARACEST agents also contain nonexchangeable protons that provide molecular readout with ultrafast chemical shift imaging, as detected by Biosensor Imaging Redundant Deviation in Shifts (BIRDS), the BIRDS properties in a cocktail of PARACEST agents will not be affected, but also enhance precision by adding redundancy for quantifying the CEST contrast.

Giaime Rancan¹, Daniela Delli Castelli², and Silvio Aime^3,4
1Technische Universität München, München, Bayern, Germany, ²University of Torino, Torino, Piemonte, Italy, ³Universitá di Torino, Torino, Piemonte, Italy, ⁴Institute for Advanced Study, Technische Universität München, Garching, Bayern, Germany

Lanthanide-HPDO3A chelates are stable and safe compounds, some of which apt for contrast agent mediated ParaCEST imaging. In this work we observe some promising candidates for functional CEST ratiometrical analyses and determine their suitability for studies at 1T field strength. An in vivo proof of concept study was performed to further investigate this methodology. The use of entry level MRI instrumentation will expand the scope of ParaCEST techniques.

Anja Müller-Lutz¹, Nadia Khalil¹, Rotem S. Lanzman¹, Georg Oeltzschner¹, Gael Pentang¹, Vladimir Jellus², Benjamin Schmitt², Gerald Antoch¹, and Hans-Jörg Wittsack^1
1University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Dusseldorf, NRW, Germany, ²Siemens, Healthcare Sector, Imaging & Therapy Division, Erlangen, BY, Germany

Chemical exchange saturation transfer (CEST) imaging with the contrast agent Iopamidol enables pH determination in vitro and in vivo. However, in vivo pH determination with Iopamidol as CEST contrast agent was only performed in animals. Nevertheless, in vivo pH measurements in human with Iopamidol at clinical used MRI systems are desirable. The aim of this study was to assess the feasibility of pH measurements with Iopamidol CEST on clinical MRI systems (3T) by using a CEST presaturation module consisting of a pulse train of presaturation pulses in vitro and to perform a first in vivo measurement in a human subject.

Nevin McVicar¹, Alex Li², Mojmir Suchy^2,3, Robert H.E Hudson³, and Robert Bartha^1,2
1Medical Biophysics, University of Western Ontario, London, ON, Canada, ²Imaging Research Group, Robarts Research Insitute, London, ON, Canada, ³Chemistry, University of Western Ontario, London, ON, Canada

In vitro properties are characterized for four paraCEST contrast agents. Each paraCEST agent was then individually injected directly into a mouse leg prior to immediate acquisition of CEST spectra. All four agents were detected in vivo. Using the properties measured in vitro along with the paraCEST contrast measured in vivo, it is concluded that in vivo performance can be predicted based on in vitro characterization of the MR properties of each agent.

Qi Liu^1,2, Ning Jin³, Zhaoyang Fan¹, Yutaka Natsuaki⁴, Wafa Tawackoli¹, Dan Gazit¹, Gadi Pelled¹, and Debiao Li^1,5
1Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States, ²Biomedical Engineering, Northwestern University, Chicago, IL, United States, ³Siemens Medical Solutions, Columbus, OH, United States, ⁴Siemens Healthcare, Los Angeles, CA, United States, ⁵University of California, Los Angeles, los angeles, California, United States

A reduced-field-of-view (rFOV) TSE method is used to reliably measure IVD gagCEST signal in vivo by reducing bowel movement artifacts on a 3.0T clinical scanner. The proposed method is verified by a phantom study, and is compared with the conventional full-FOV CEST technique on nine volunteers.

Richard D. Dortch^1,2, Ke Li^1,2, Daniel F. Gochberg^1,2, John C. Gore^1,2, and Seth A. Smith^1,2
1Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States, ²Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States

The purpose of this study was to optimize the selective inversion recovery (SIR) quantitative magnetization transfer sequence for mapping of the macromolecular-to-free proton pool size ratio (PSR). Previous work has demonstrated that PSR is related to myelin content. Despite this promise, the time required for SIR imaging can be prohibitively long. Here, we reduce to total number of samples required for SIR imaging by fixing the rate of MT exchange and choosing a sampling strategy that minimizes the bias in PSR. Results indicate that unbiased, high SNR estimates of PSR can be obtained using this optimized approach.

Gopal Varma¹, Gottfried Schlaug², and David C. Alsop^1
1Radiology, Division of MR Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States, ²Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States

The contrast from inhomogeneous MT (IHMT) appears more specific to white matter (WM) than regular MT imaging, and requires fewer acquisitions than T₂ mapping. However prior work with IHMT is limited to single slice acquisition. IHMT is developed towards a 3D acquisition based on traditional MT sequences: 3D IHMT data were obtained in vivo using spoiled gradient-echo acquisitions in ~5 minutes. The nature of the IHMT acquisition also provides MT images for direct comparison. IHMT and MT ratios from WM, and basal ganglia grey matter (BG GM) are compared and a greater difference is observed between WM and BG GM from the IHMT technique.

Pouria Mossahebi¹, Andrew L. Alexander^2,3, Aaron S. Field^1,4, and Alexey A. Samsonov^4
1Biomedical Engineering, University of Wisconsin, Madison, WI, United States, ²Medical Physics, University of Wisconsin, Madison, WI, United States, ³Waisman Lab for Brain Imaging and Behavior, University of Wisconsin, Madison, WI, United States, ⁴Radiology, University of Wisconsin, Madison, WI, United States

This study was performed to investigate the effect of non-exchanging component in quantitative magnetization transfer (qMT) parameters estimation. We have introduced third (non-exchanging or very slowly exchanging) pool to the common two-pool model used in majority of qMT imaging. The presence of such non-exchanging or very slowly exchanging compartments may result in significant underestimation of key parameters of qMT, especially in gray matter (GM) where significant partial volume effect (PVE) from cerebrospinal fluid (CSF). Our results show that this model can remove partial volume effect (PVE) from non-exchanging pool on qMT parameters maps.

Nevin McVicar¹, Alex Li², Robert Bartha², Daniela F. Goncalves^3,4, Susan Meakin², and Marco A. Prado^2
1Medical Biophysics, University of Western Ontario (UWO), London, ON, Canada, ²Robarts Research Institute, London, ON, Canada, ³Physiology and Pharmacology, UWO, London, ON, Canada, ⁴Graduate Program in Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil

A novel ratiometric CEST approach is developed for amine/amide concentration independent detection (AACID) of intracellular pH. In vitro results demonstrate a linear relation between pH and the amine/amide CEST ratio. In vivo pH-calibration allowed quantitative pH mapping in both stroke and brain tumor mouse models.

Anja Müller-Lutz¹, Benedikt Ostendorf¹, Christoph Schleich¹, Nadia Khalil¹, Benjamin Schmitt², Vladimir Jellus², Philipp Sewerin¹, Axel Scherer¹, Georg Oeltzschner¹, Gael Pentang¹, Matthias Schneider¹, Gerald Antoch¹, Hans-Jörg Wittsack¹, and Falk Miese^1
1University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Dusseldorf, NRW, Germany, ²Siemens, Healthcare Sector, Imaging & Therapy Division, Erlangen, BY, Germany

MRI plays an increasing role in the diagnosis and treatment monitoring of arthritis. Next to synovitis, erosions and osteoedema, cartilage composition is of increasing importance in the research of arthritis. gagCEST has recently been demonstrated to be sensitive to alterations in the biochemical composition of cartilage in the knee in patients following cartilage repair surgery as well as in vertebral disks. Our work shows the feasibility of gagCEST imaging in finger joint cartilage in healthy volunteers and patients with rheumatoid arthritis.

Jae-Seung Lee^1,2, Prodromos Parasoglou¹, Ding Xia¹, Alexej Jerschow², and Ravinder R. Regatte^1
1Radiology, New York University, New York, NY, United States, ²Chemistry, New York University, New York, NY, United States

The in-vivo quantification of glycosaminoglycan (GAG) concentration is important for the early diagnosis of osteoarthritis. One promising method to measure GAG content in articular cartilage is chemical exchange saturation transfer (CEST). However, the CEST measurement may be interfered with the magnetization transfer (MT) effects resulting from the background extracelluar matrix. Recently, we have proposed a new strategy to disentangle CEST effects from asymmetric MT effects by using a simultaneous two-frequency RF irradiation technique to make the MT effects uniform. For the first time, this uniform-MT CEST method is applied in an in vivo human knee MRI study.

Zhongliang Zu¹, Junzhong Xu¹, Vaibhav Janve¹, Christopher C. Quarles¹, Mark D. Does¹, John C. Gore¹, and Daniel F. Gochberg^1
1Institue of Imaging Science, Vanderbilt University, Nashville, TN, United States

Creatine imaging may provide useful biological information. MRS is able to image creatine. However, it suffers from relatively low resolution and long acquisition times. Here, we provide a chemical exchange filter imaging technique based on the recently developed chemical exchange rotation transfer (CERT) approach, that can select specific metabolites based on their exchange rates with water. Known phantom experiments show that CERT signal from creatine dominates signals from other metabolites. In vivo experiments on a rat brain with 9L tumor show that creatine imaging using CERT may serve as a new imaging biomarker to detect cancer.

Shaokuan Zheng¹, Imramsjah M.J. van der Bom¹, Zhongliang Zu², Guoxing Lin³, Matthew J. Gounis¹, and Yansong Zhao^4
1Radiology, UMASS Medical School, Worcester, MA, United States, ²Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States, ³Gustav H. Carlson School of Chemistry, Clark University, Worcester, MA, United States, ⁴Philips Healthcare, Cleveland, OH, United States

Due to flow sensitivity of non-enhanced MRA, neurovascular diseases that present with slow or complex flow may not be fully appreciated. The feasibility of using Chemical Exchange Transfer Saturation (CEST) as angiography method is investigated. CEST imaging was performed on blood samples and the femoral artery of healthy human volunteers. The blood sample experiments showed that CEST contrast of 16% was achieved. In vivo CEST signal of blood was an order of magnitude greater than surrounding muscular tissue. Preliminary results show that blood is a suitable CEST agent that generates sufficient contrast to allow for angiographic imaging.

Moriel Vandsburger¹, Avigdor Leftin¹, Senzeni Mpofu¹, and Michal Neeman^1
1Weizmann Institute of Science, Rehovot, None, Israel

Chemical exchange saturation transfer (CEST) imaging is emerging as a powerful MRI technique for selective visualization of a variety of targeted contrast agents and synthetic reporter genes. CEST imaging has been applied primarily to stationary organs or tumors, and never to the heart because of cardiac and respiratory motion. We developed a free breathing, retrospectively gated, CEST-encoded steady state gradient echo cardiac cine imaging sequence for the purpose of pre-clinical cardiac CEST imaging.

Junzhong Xu¹, Zhongliang Zu¹, Jingping Xie¹, Daniel F. Gochberg¹, and John C. Gore^1
1Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States

To investigate whether the APT contrast in vivo reflects real differences in protein concentrations between tumors and normal tissues, we correlated APT contrast with multiple other MR parameters and protein concentration in 9L gliomas and normal tissues. R1 and PSR confirm that the total macromolecular content relevant for affecting water relaxation is lower in tumors, whereas APT and R2 detect other variations in composition that cause an increased contribution from exchanging protons. In additional, nuclear Overhauser effects (NOE) were also investigated which may provide a new imaging parameter to detect cancer, and the underlying biophysical mechanism is under investigation.

Mariya Doneva¹, Jochen Keupp¹, Silke Hey², Osamu Togao³, and Takashi Yoshiura^3
1Philips Research Europe, Hamburg, Germany, ²Philips Healthcare, Best, Netherlands, ³Department of Clinical Radiology, Kyushu University, Fukuoka, Japan

Amide proton transfer (APT) is a novel contrast mechanism enabling molecular MR imaging of proteins as well as the assessment of local pH. Clinical applications of APT imaging are often limited to a single slice acquisition due to the long scan time caused by multiple acquisitions at different saturation offset frequencies as well as SAR limitations. Previous studies were mainly focused on low resolution scans with large number of saturation offset frequencies and short saturation times Tsat < 1s. Parallel transmission based APT enables long saturation pulses at 100% duty cycle at clinical scanners and it was recently shown that an optimal CNR efficiency can be achieved at Tsat ≈ 2s. The purpose of this work was to investigate the application of 3D APT sequences with optimized saturation length and whole brain coverage. 3D GRASE and fast spin echo (TSE) sequences for APT were compared in phantom and in vivo studies.

Yee Kai Tee¹, Manus J. Donahue², Stephen J. Payne¹, and Michael A. Chappell^1
1Department of Engineering Science, University of Oxford, Oxford, Oxfordshire, United Kingdom, ²Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, United States

Gadolinium contrast agents (Gd-CA) are widely used in clinical perfusion MRI. Amide proton transfer (APT) imaging is an emerging chemical exchange saturation transfer MRI technique for pH mapping that may provide complementary information to perfusion MRI in various clinical applications such as cancer and stroke. In this study, we compared the APT quantification pre- and post-Gd-CA infusion, and found that in some cases the APT effect showed significant difference after contrast administration even when using an asymmetry measure.

Chao Xu¹, Christian Labadie¹, André Pampel¹, Samer Salamekh¹, and Harald E. Möller^1
1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

Two-frequency radiofrequency (RF) irradiation was claimed to allow the isolation of the chemical exchange saturation (CEST) from magnetization transfer (MT) asymmetry. We implemented this technique for detecting pH-dependent APT effect in a clinical 3T MRI scanner and compared the experimental data acquired from egg white solutions with the simulation result using a three-pool model. According to our study, the double-frequency irradiation enables the partial correction of the MT asymmetry. A linear dependence between pH and measured MTRasym by the double-frequency pulse was observed in the cross-linked egg white solutions.

Phillip Zhe Sun¹, Jerry S. Cheung¹, Enfeng Wang¹, and Xiaoan Zhang^2
1Radiology, Martinos Center for Biomedical Imaging, Charlestown, MA, United States, ²Radiology, 3rd Affiliated Hospital, Zhengzhou, Henan, China

pH-sensitive APT MRI is a metabolic index that remains promising to define ischemic tissue injury. We evaluated ischemic tissue response to reperfusion with multi-parametric MRI, and our results showed that quantitative pH imaging delineated salvageable DWI lesion from the irreversibly injured ischemic core. Therefore, it is important to develop multi-parametric tissue outcome prediction model that combines perfusion, pH and diffusion MRI, which may more accurately identify salvageable ischemic tissue for late thrombolytic therapy and ultimately help guide the development of neuroprotection agents that target tissue acidosis.

Mariya Doneva¹, Ulrich Katscher¹, Christian Stehning¹, Osamu Togao², and Jochen Keupp^1
1Philips Research Europe, Hamburg, Germany, ²Department of Clinical Radiology, Kyushu University, Fukuoka, Japan

Amide proton transfer (APT) and electric properties tomography (EPT) are two novel MR methods for molecular and quantitative imaging of tissue properties. The APT signal is defined by the asymmetry of the magnetization transfer (MT) at +3.5ppm relative to water and reflects the concentration of endogenous cytosolic proteins or peptides as well as local pH. EPT is based on the curvature of the transceive phase (B1 field) of a fast spin echo (FSE) or balanced steady state free precession (bSSFP) image and reflects the electric conductivity of the tissue. Both elevated protein levels and tissue conductivity are related to pathological changes in tumors. Acquisition of the two contrasts in the same imaging sequence could potentially deliver complementary information for tumor tissue characterization and reduce the scan time compared to acquiring APT and EPT in separate scans. In this work, we propose an FSE acquisition, which allows the reconstruction of APT and EPT data from the same imaging sequence and demonstrate its feasibility in phantom and in vivo experiments.

Marilena Rega¹, Francisco Torrealdea¹, Phillip Smethurst¹, James Dick¹, Anna Gray¹, Linda Greensmith¹, Katie Sidle¹, Simon Walker-Samuel², David L. Thomas¹, and Xavier Golay^3
1Institute of Neurology, UCL, London, Greater London, United Kingdom, ²Centre for Advance Biomedical Imaging, UCL, London, Greater London, United Kingdom, ³Institute of Neurology, University College London, London, Greater London, United Kingdom

Amide proton transfer (APT) is able to produce contrast originating from endogenous cellular proteins and peptides. In this study we explore the possibility of using APT as a biomarker of Amyotrophic lateral sclerosis (ALS) through a SOD1 mutate mouse model that closely resembles the disease. Comparisons of the APT signal between healthy and SOD1 animals at the same age, as well as validation of the results with protein assays (ex-vivo) show a significant difference between the two groups at a pre-symptomatic stage of the disease. These results suggest that APT could potentially become an early biomarker for ALS.

Henrik Marschner¹, Dirk K. Müller¹, André Pampel¹, Jane Neumann¹, and Harald E. Möller^1
1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

We examine whether Artificial Neural Networks (ANN) can be trained to estimate MT parameter sets from sparsely sampled in-vivo MT data. ANNs were trained using densely sampled MT data from healthy volunteers and the MT parameters obtained using conventional fitting as input. ANNs were used to extract MT parameters from sparsely sampled data. The obtained parameters were compared with those that come out using the conventional method. It is shown that parameters obtained with both methods are highly correlated (R>0.97). Once ANNs are trained subsequent measurements of other individuals and parameter estimation can be notably accelerated.

Jiadi Xu^1,2, Nirbhay N. Yadav^1,2, Kannie W.Y. Chan^1,2, Amnon Bar-Shir², Qin Qin^1,2, Guanshu Liu^1,2, Michael T. McMahon^1,2, and Peter C.M. van Zijl^1,2
1F. M. Kirby Center, Kennedy Krieger Institute, Baltimore, MD, United States, ²Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, United States

A T2 relaxation dispersion technique is proposed to detect low concentration metabolites with protons that exchange in the intermediate to fast regime on the MR time scale. It employs a Carr-Purcell-Meiboom-Gill (CPMG) pulse train module with a fixed total length. The R2 (1/T2) values measured are dispersed by changing the number of 180 pulses in this module, which varies the pulse spacing. The dispersion curves reflect the concentration, exchange rate, and chemical shift difference of the exchangeable protons with water. The technique easily detects glutamate, myo-inositol and creatine and can quantify their exchange properties.

Zhongliang Zu¹, Junzhong Xu¹, Hua Li¹, Christopher C. Quarles¹, Mark D. Does¹, John C. Gore¹, and Daniel F. Gochberg^1
1Institue of Imaging Science, Vanderbilt University, Nashville, TN, United States

CEST Z-spectra show dips from exchangeable sites (-NH2, -NH, and OH) at down field frequencies and from Nuclear Overhauser Enhancement (NOE) at up field frequencies. Quantitative mapping of such effects is difficult as conventional asymmetric analyses include contributions from both exchangeable sites and NOE. Here, we use a modified CEST method, chemical exchange ration transfer (CERT), to quantify amide proton transfer (APT) and NOE through subtraction of CEST signals at two irradiation flip angles instead of two frequency offsets. In vivo experiments on a rat brain with 9L tumor show interesting contrasts from APT and NOE.

Chao Ma^1,2 and Zhi-Pei Liang^1,2
1Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States, ²Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, United States

The SLR method is the “method-of-choice” in 1D RF pulse design. It is desirable to generalize the SLR method to design multidimensional RF pulses, which is accomplished in this work. We convert the problem to a series of 1D RF pulse design problems, each of which is equivalent to a 1D polynomial design problem that can be efficiently solved using convex optimization. The proposed method preserves almost all the desirable features of the SLR method in terms of handling the nonlinearity of the Bloch equation and tradeoffs among design parameters and computational efficiency.

Rolf F. Schulte¹ and Florian Wiesinger^1
1GE Global Research, Munich, Germany

Multi-dimensional RF pulses are used in special applications like targeted excitation or spectrally-spatially selective excitation. Commonly, spectral-spatial pulses are designed in a separable design, by first choosing a suitable gradient trajectory, designing a 1D spectral and a 1D spatial filter function and finally combining this into the actual 2D pulse. In this work, we introduce a simple 2D pulse design by direct matrix inversion, which helps to reduce sideband artefacts. Exemplary spectral-spatial pulses as well as 2D pulses with a quadratic phase are designed which can be used for efficient CSI encoding using SPEN.

Ronald Mooiweer¹, Alessandro Sbrizzi¹, Hamza el Aidi¹, Cornelis A.T. van den Berg¹, Fredy Visser^1,2, Tim Leiner¹, Peter R. Luijten¹, and Hans Hoogduin^1
1UMC Utrecht, Utrecht, Utrecht, Netherlands, ²Philips Healthcare, Best, Noord-Brabant, Netherlands

Spatially Selective Excitation in combination with reduced field of view imaging was used to efficiently image the aortic vessel wall over a large trajectory.

Irene M.L. van Kalleveen¹, Hugo Kroeze¹, Alessandro Sbrizzi¹, Vincent Oltman Boer², Reerink Onne¹, Marielle E.P. Philippens¹, Cornelis A.T. van den Berg¹, Peter R. Luijten¹, and Dennis W.J. Klomp^1
1Radiology, UMC Utrecht, Utrecht, Utrecht, Netherlands, ²Radiology, University Medical Center Utrecht, Utrecht, Utrecht, Netherlands

In high field clinical MRI the B1 field is limited and inhomogeneous, while RF power deposition is high. The use of local antennas at 7T can be beneficial to image for example the rectal wall. However the B1 inhomogeneity becomes even more challenging when using internal transceivers. To compensate for their radial B1 inhomogeneity, we designed a 2D compensating RF pulse. In combination with two harmonic gradients the RF pulse provides a uniform flip angle in two dimensions as demonstrated by 3D FFE in the human rectum.

Mads Sloth Vinding¹, Ivan I. Maximov², Zdenek Tosner³, and Niels Christian Nielsen^1
1iNANO, inSPIN, Aarhus University, Aarhus, Jutland, Denmark, ²Institute of Neuroscience and Medicine 4, Juelich, Germany, ³Charles University, Prague, Czech Republic

We present numerical simulations of B0 and B1 inhomogeneity compensation for 2D RF pulses derived using a monotonical convergent optimal control algorithm. The algorithm has proven rather fast compared to other gradient-based methods which is paramount for in vivo applications and it is quite robust with respect to the initial guess. Following up on our recent published experimental validation we here show that the algorithm in this study is capable of alleviating B0 inhomogeneity in a fictive B0 map of a 250 Hz linewidth, as well as B1 inhomogeneity of at least 9% inside the ROI.

Yi-Cheng Hsu¹, Ying-Hua Chu², Thomas Witzel³, I-Liang Chern⁴, and Fa-Hsuan Lin^2
1Department of Mathematics, Nnational Taiwan University, Taipei, Taiwan, ²Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan, ³A. A. Martinos Center, Massachusetts General Hospital, Charlestown, MA, United States, ⁴Department of Mathematics, National Taiwan University, Taipei, Taiwan

To mitigate the B1+ inhomogeneity and to achieve more homogeneous large flip angle in high field MRI, we propose a method of composite excitation pulses, which does not require the refocusing slice selection gradient between two pulses. At 3T MRI, we demonstrate and compare this method to the standard single pulse excitation and a previously reported two-pulse method. We also used the Bloch equation to simulate the magnetization after our two-pulse excitation over a slice FOV to prove that our proposed composite pulses method can also work with slice-selective pulses.

Hans Weber¹, Martin Haas¹, Denis Kokorin^1,2, Jürgen Hennig¹, and Maxim Zaitsev^1
1Department of Radiology, Medical Physics, University Medical Center Freiburg, Freiburg, Germany, ²International Tomography Center, Novosibirsk, Russian Federation

ExLoc allows excitation and geometrically matched spatial encoding of customized curved slices, based on a combination of linear and nonlinear gradients. The combination of ExLoc with multidimensional RF-pulses allows compensating for varying slice thickness originating from the nonlinearity of the applied slice-selection field. In this study, we exploit this technique for additional local adaptation of the slice shape. Compared to conventional multi-dimensional excitation with linear encoding fields to excite a curved slice, using this approach allows considerably shorter RF-pulses to be used.

Jakob Assländer¹ and Jürgen Hennig^1
1Dept. of Radiology - Medical Physics, University Medical Center Freiburg, Freiburg, Germany

A type of global pulses is proposed that pre-wind the phase of the spin ensemble within a finite frequency range. The resulting phase distribution in the particular frequency range is similar to the one after the combination of excitation and refocusing pulse in a standard spin echo experiment. The result is a spin echo formation after a single excitation pulse. Choosing a small tip angle, most of the longitudinal magnetization is maintained, potentially allowing T₂-weighted imaging at low repetition times, e.g. for 3D encoding.

Martin Haas¹, Denis Kokorin¹, Stefanie Buchenau¹, Ara K. Yeramian¹, Hans-Peter Fautz², Tobias Wichmann³, Jürgen Hennig¹, Michael Bock¹, and Maxim Zaitsev^1
1Medical Physics, Department of Radiology, University Medical Center Freiburg, Freiburg, Germany, ²Siemens Healthcare, Erlangen, Germany, ³RAPID Biomedical GmbH, Rimpar, Germany

Inner volume imaging with multi-dimensionally selective RF pulses has become feasible with introduction of parallel transmit acceleration techniques. Small organs like the kidney can profit from IVI, where the significant reduction of phase encoding steps decreases the acquisition time, which is limited by the patient’s ability to hold their breath. In this work, selective excitation of the right kidney of a volunteer is demonstrated, using eight-channel accelerated parallel transmit selective excitation. The kidney is imaged using segmented EPI in one breathhold and T2* maps are acquired with the aim to assess oxygenation changes in cortex and medulla under water loading.

Alexis Amadon¹, Alexandre Vignaud¹, Aurélien Massire¹, Michel Bottlaender¹, and Nicolas Boulant^1
1CEA, DSV, I2BM, Neurospin, LRMN, Gif-sur-Yvette, France, France

Parallel transmission allows shortening fancy spatially-selective RF pulses. For a parallelepiped volume of interest, we investigate the possibility to use a mere 2D-spiral in excitation k-space to insure 3D selectivity for Inner Volume Imaging or CSI, by making the third dimension be the readout axis of a 3D sequence. We thereby observe to what extent the excitation profile is preserved along the readout direction. Moreover we demonstrate a zooming application on an ex-vivo baboon brain at 7T.

Rainer Schneider^1,2, Bastien Guérin³, Michael Hamm¹, Jens Haueisen², Elfar Adalsteinsson^4,5, Lawrence L. Wald^5,6, and Josef Pfeuffer^1
1Siemens Healthcare, MR Application Development, Erlangen, Germany, ²Institute of Biomedical Engineering and Informatics, Ilmenau University of Technology, Ilmenau, Germany, ³Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ⁴Dept of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, United States, ⁵Harvard-MIT Division of Health Sciences Technology, Cambridge, MA, United States, ⁶Martinos Center for Biomedical Imaging, Dept. of Radiology, Massachusetts General Hospital, Charlestown, MA, United States

The increased number of TX channels and Z-stacked pTX array geometry has been shown beneficial for better B1-shimming performance. No studies are known so far analyzing the different coil configurations for spatially-selective RF pulses. We simulate transverse and sagittal SSP pulses for two single-row arrays and a Z-stacked 3T body multi-channel TX array. Simulation results are analyzed with respect to TX acceleration factors and RF hardware efficiency. The Z-stacked coil setup shows significant gains in hardware efficiency and excitation performance along the sagittal direction, but also benefits along transverse direction. The beneficial effects are more prominent at higher acceleration factors.

Xiaoping Wu¹, Kamil Ugurbil¹, and Pierre-Francois Van de Moortele^1
1CMRR, Radiology, University of Minnesota, Minneapolis, MN, United States

The use of multi-band (MB) RF excitation along with subsequent unaliasing via parallel imaging principles leads to significant acceleration in volume coverage along the slice direction; this approach is becoming increasingly common and has recently been demonstrated with significant success in functional and diffusion-weighted imaging studies of the brain. Conventionally, the total RF energy and peak RF power required in slice accelerated MB imaging increase linearly and approximately quadratically, respectively, with the MB factor that defines the number of simultaneously excited slices. This increase can easily limit the maximum MB factor, especially when spin echo acquisitions are required and/or high magnetic fields are employed. Here we introduce a novel formulation for optimum peak power constraint using MB pTx pulse design based on spoke RF pulses with simultaneously targeting improved B1+ inhomogeneity. The formulation incorporates the interaction of the base pulses of individual bands by taking into account the final summed pulses. The new formulation is validated using B1+ maps simulated in a human whole body model and is shown to result in larger reduction of peak RF power than the conventional formulation for pTx pulses used for optimizing single-slice or sequential multi-slice excitation.

Ulrich Katscher¹, Kay Nehrke¹, and Peter Boernert^1
1Philips Research Europe, Hamburg, Germany

Usually, Transmit SENSE is applied to improve spatially selective RF pulses in two or three dimensions. This study investigates the application of Transmit SENSE to one-dimensional RF pulses. For these RF pulses, Transmit SENSE is applicable in case of large B1 variations across the slice or slab to be excited as found for 3D volume imaging or REST. 1D Transmit SENSE can improve the excitation profile and reduce the required RF power. The approach was tested in vivo in the framework of a commercial 3T system with two transmit channels using the recently developed, ultrafast B1-mapping technique DREAM.

Shuo Feng¹ and Jim X. Ji^1
1Electrical and Computer Engineering, Texas A&M University, College Station, Texas, United States

Spatially selective excitations with transmit array have been regarded as a key in solving several problems in high field MRI such as the transmit field inhomogeneity and the high power deposition. However, pulse design can be time consuming which may hinder its use from real-time applications. In this work, we propose a fast pulse design method by exploring the sparsity of the target spatial excitation pattern. The size of the system equation can be significantly reduced after a sparse transform and therefore the design speed is increased. Computer simulations in several common scenarios show that the proposed design method can achieve up to an order-of-magnitude speedup than the conventional design methods while still maintaining similar excitation accuracy.

Nicolas Boulant¹, Aurelien Massire¹, and Alexis Amadon^1
1Neurospin, CEA, Saclay, Ile de France, France

In their investigations, radiofrequency pulse designers often use flip angle measurements to validate their new developments. However when the objective is to implement true target matrix rotations, as for instance in the spin-echo sequence, those measurements inform about the performance of the RF pulse only for a particular input state. For the first time in MRI, we report the implementation of a Quantum Process Tomography experiment at 7 Tesla in order to characterize a transmit-SENSE 180° refocusing RF pulse, thereby providing information about the performance of the operation regardless of the input state.

Aurélien Massire¹, Martijn A. Cloos², Alexandre Vignaud¹, Denis Le Bihan¹, Alexis Amadon¹, and Nicolas Boulant^1
1CEA DSV I2BM NEUROSPIN LRMN, Gif-sur-Yvette, France, ²Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, NY, United States

We use gradient ascent pulse engineering combined with the kT-point method to design non-selective refocusing pulses that mitigate severe B1 and ΔB0 inhomogeneities. The novelty of the method lays in the optimization of the relevant rotation matrices themselves rather than magnetization states. Experimental validation was performed on a phantom and using a 7 T scanner equipped with an 8-channel transmit array. The rotation matrix on every voxel was measured using Quantum Process Tomography. In addition, a modified non-selective Spin-Echo sequence was run to evaluate the ability to refocus dephased magnetization. Both experiments confirmed high fidelity of the here-introduced technique.

Martijn A. Cloos¹, Wonje Lee², Graham C. Wiggins², and Daniel Sodickson^2,3
1Radiology, New York University School of Medicine, New York, NY, United States, ²Radiology, New York University Langone Medical Center, New York, NY, United States, ³The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, United States

In the recent past several publications have demonstrated parallel transmission for flip-angle homogenization at ultra-high field in the human brain. In this work we introduce, the asymmetric spokes design for slab-selective imaging with reduced echo times. To facilitate a completely free-breathing protocol, an optimized B1-mapping approach is detailed. Subsequently, the comprehensive method is demonstrated by homogenizing the flip-angle on a 6cm axial slab through the human torso at 7T using the 3DVIBE sequence.

Patrick Waxmann¹, Tomasz Dawid Lindel¹, Frank Seifert¹, Bernd Ittermann¹, and Ralf Mekle^1
1Physikalisch-Technische Bundesanstalt, Berlin, Germany, Germany

Single voxel MR spectroscopy desires to acquire spectra from an anatomically defined region of interest. Spatially selective excitation (SSE) has been studied to adapt the voxel shape to the anatomy. Segmentation of SSE pulses can enhance the excitation bandwidth. Here, we introduce an off-resonance correction for segmented SSE-pulses designed with a small-tip-angle algorithm. The pulses can be designed as a whole and segmented only afterwards. This correction enhances target pattern fidelity even for large off-resonances and thus provides for uniform voxel localization over a wide frequency range.

Ingmar Graesslin¹, Annighoefer Bjoern¹, Ulrich Katscher¹, and Peter Börnert^2
1Philips Research, Hamburg, Germany, ²Philips Research Laboratory, Hamburg, Germany

Parallel transmission in high-field MRI can improve the B1 homogeneity, as well as speed up multidimensional RF pulses (Transmit SENSE). However, the calculation of such pulses often takes too long for the use in a clinical setting, in particular if RF safety constraints are considered. This work presents a novel simple and efficient approach to calculate selective RF pulses for arbitrary target patterns based on pre-calculated base pulses. The base pulses can be precalculated by using arbitrary RF pulse design algorithms. They can be optimized for SAR or power and are valid for certain k-space trajectories and transmit coil arrangements.

Rainer Schneider^1,2, Matthias Gebhardt¹, Jens Haueisen², and Josef Pfeuffer^1
1Siemens Healthcare, MR Application Development, Erlangen, Germany, ²Institute of Biomedical Engineering and Informatics, Ilmenau University of Technology, Ilmenau, Germany

A lot of work has been done towards SAR-constrained optimization in pTX. However, in clinical use these methods can be too computationally intensive for highly parameterized spatially selective pulses. We propose a target-pattern-driven variable-density k-space trajectory (TD) metric, which inherently offers significant RF hardware efficiency and a beneficial impact on local and global SAR performance. To evaluate potential benefits of the TD approach, an elaborate simulation study for an 8ch 3T whole-body multi-channel TX array was conducted. The TD method was applied to a 3D-selective stack-of-spirals trajectory and compared to equal and fixed variable-density designs for varying TX acceleration factors.

Marcin Jankiewicz¹ and Jay Moore^2
1MRC/UCT Medical Imaging Research Unit, Department of Human Biology, University of Cape Town, Observatory, Western Cape, South Africa, ²Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States

We show a construction that enables the design and implementation of semi-adiabatic waveforms with performance optimized on a set of grids of predefined (B₁⁺)i and Δf₀ values associated with a multi-channel transmission system.

Shaihan J. Malik¹ and Joseph V. Hajnal^1
1Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, London, United Kingdom

Dynamic RF shimming using a Spatially-Resolved Extended Phase Graph signal model was recently proposed for optimising pseudo-steady-state pulse sequences. The SR-EPG framework is more powerful than simple RF shimming because it considers the effect on the signal from multiple RF pulses. The original method modelled the transient state arising from a single shot, neglecting the effect of incomplete (and spatially variable) recovery that really occurs during multi-shot sequences. This leads to suboptimal results when such sequences are used in practice. In this work the steady-state that arises after multiple shots is modelled and optimized directly, improving the resulting solutions.

Stephen James Wastling¹ and Gareth John Barker^1
1Department of Neuroimaging, King's College London, London, United Kingdom

GE-EPI images suffer from signal dropout caused by susceptibility gradients. This can be reduced using Hyperbolic Secant (HS) RF excitation pulses with quadratic phase profiles. We determine by Bloch simulation the HS pulse parameters to give the most uniform signal response across the range of susceptibility gradients observed in the human head and show that the previous theoretical model for this is inaccurate. We also derive an expression for the bandwidth of a HS pulse used for excitation that is flip angle dependent. Finally using our optimised pulse we demonstrate recovery of signal in regions of dropout in six subjects.

Florent Eggenschwiler¹, Rolf Gruetter², and José P. Marques^3
1EPFL, Laboratory for Functional and Metabolic Imaging, Lausanne, Vaud, Switzerland, ²Universities of Geneva and Lausanne, École Polytechnique Fédérale de Lausanne, Lausanne, Vaud, Switzerland, ³University of Lausanne, Department of Radiology, Lausanne, Vaud, Switzerland

This work presents a new approach for designing high tip angle k_T-point pulses based on a linearization of the Bloch equations and usage of symbolic notation to accelerate the computation when the optimization has to be performed for large number of pixels. Based on the differentiation of the analytic form of the Bloch equations, the k_T-point weights and positions were iteratively optimized in order to converge towards a targeted distribution of the magnetization across the brain. The validity of the method was demonstrated by designing high tip angle k_T-points excitation and refocusing pulses.

Min-Oh Kim¹, Jaewook Shin¹, Narae Choi¹, Joonsung Lee¹, and Dong-Hyun Kim^1
1Electrical and Electronic Engineering, Yonsei University, Seoul, Korea

An extremely fast B1 mapping method is proposed based on the oscillatory signal behaviors in transient phase of /3balanced SSFP (bSSFP) sequences.

Mohammad Mehdi Khalighi¹, Adam B. Kerr², and Brian K. Rutt^3
1Applied Science Lab, GE Healthcare, Menlo Park, California, United States, ²Department of Electrical Engineering, Stanford University, Stanford, California, United States,³Department of Radiology, Stanford University, Stanford, California, United States

The adiabatic Bloch-Siegert (B-S) method has been introduced to design short highly sensitive frequency-swept B-S pulses to address the long TE and high SAR problems of B-S B₁⁺ mapping method; however, it is not clear which ABS pulse width gives the best results. Here we have compared ABS pulses with different pulse widths and showed that the best ABS pulse width, which generates the highest angle-to-noise ratio (ANR) is ¾ T₂^*. We used 2, 4 and 6ms ABS pulses in brain at 7T and showed that 6ms ABS pulse generates highest ANR maps.

Xiaoying Cai¹, Wu Dan², and Jiangyang Zhang^3
1Biomedical Engineering, Tsinghua University, Beijing, Beijing, China, ²Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States,³Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States

We propose the use of a twin-navigator phase correction scheme to monitor and correct phase errors in fast spin echo Bloch-Siegert B1 mapping sequences. The proposed sequence was implemented and tested on an 11.7T MR system. With phase correction, both individual phase images and calculated B1 maps contained fewer artifacts. The technique can be used to acquire 3D B1 map on high field magnet and tolerate certain degree of subject motion and instrument instability.

Esra Abaci Turk^1,2, Yusuf Ziya Ider¹, Arif Sanli Ergun³, and Ergin Atalar^1,2
1Electrical and Electronics Engineering Department, Bilkent University, Ankara, Turkey, ²National Magnetic Resonance Research Center (UMRAM), Ankara, Turkey, ³Electrical and Electronics Engineering Department, TOBB-University of Economics and Technology, Ankara, Turkey

In this study, a new simple Fourier domain based analytical expression is proposed for the Bloch-Siegert phase shift based B1 mapping method. With this new expression off- and on-resonance effects can be understood more easily due to the Fourier domain relation. It is shown that |B₁⁺| can be obtained more accurately by the aid of this expression for short pulse durations and offset frequencies.

Alois M. Sprinkart^1,2, Georg Schmitz², Frank Träber¹, Wolfgang Block¹, Jürgen Gieseke³, Winfried A. Willinek¹, Hans H. Schild¹, Peter Börnert⁴, and Kay Nehrke^4
1Dept. of Radiology, University of Bonn, Bonn, Germany, ²Institute of Medical Engineering, Ruhr-University Bochum, Bochum, Germany, ³Philips Healthcare, Hamburg, Germany,⁴Philips Research Laboratory, Hamburg, Germany

The recently published ultra-fast B₁⁺ mapping approach DREAM was used to acquire an volumetric B₁⁺ calibration dataset of the whole upper abdomen with an isotropic voxel size of 4.7mm within a single breath-hold acquisition in 12 patients and 2 volunteers at 3T. Based on this data RF settings were optimized separately for each of 60 transversal and 40 coronal reformatted slices, adaptive to position and angulations to evaluate potential improvements in flip angle accuracy and B₁⁺ homogeneity by multi-slice adapative RF shimming. Results were compared to conventional transversal single-slice optimization approach.

Kay Nehrke¹, Alois M. Sprinkart^2,3, Hans H. Schild², and Peter Börnert^1
1Philips Research Laboratory, Hamburg, Germany, ²Department of Radiology, University of Bonn, Bonn, Germany, ³Institute of Medical Engineering, Ruhr-University Bochum, Bochum, Germany

The recently introduced DREAM B₁⁺ mapping approach has been combined with a black-blood prepulse to allow a 2D B₁⁺ map of the heart to be acquired in the diastolic phase of a single heart beat. The approach has been studied in vivo for RF shimming of the heart using a dual-transmit 3T MRI system. Application of the black blood prepulse facilitated automatic threshold-based masking of the B₁⁺ maps, thus improving the reliability of the maps. RF shimming resulted in significant improvement of RF homogeneity.

Yi Wang^1,2, Glen Morrell², and Dennis L. Parker^2
1Neurology, University of California, Los Angeles, Los Angeles, California, United States, ²Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah, United States

SSFP sequences offer superior signal intensity in a relative short time. The potential of a dual-echo SSFP sequence has been investigated for breast imaging applications, where fat signal is separated from the water signal using the two-point Dixon technique [3]. Dual echo SSFP provides robust water-only and fat-only images in the presence of B0 and B1 inhomogeneity. Due to the sensitivity of SSFP to off resonance, short TR is needed to minimize the banding artifact. The two echoes required for the two-point Dixon fat-water separation can be acquired using a bipolar gradient. Compared to mono-polar readout, a bipolar gradient can reduce echo spacing and therefore result in more efficient readout. However, due to the opposite chemical shift, mis-registration between images from the two echoes using bipolar readouts exists. In this work, we improved the dual-echo 3D SSFP sequence by correcting the bi-directional chemical shift error in two-point Dixon fat/water separation.

Thomas Benkert¹, Riad Ababneh², Martin Blaimer¹, Peter M. Jakob^1,3, and Felix A. Breuer^1
1Research Center Magnetic Resonance Bavaria, Würzburg, Bavaria, Germany, ²Yarmouk University, Irbid, Jordan, ³Experimental Physics 5, University Würzburg, Würzburg, Bavaria, Germany

To achieve fat water separation out of just one single acquisition, we propose a golden ratio radial bSSFP sequence. The echotime of each radial projection is shifted dynamically, allowing to extract images with different echotimes by using a k-space weighted image contrast (KWIC) filter.

Markus Florian Untenberger¹, Martin Uecker², Dirk Voit¹, and Jens Frahm^3
1Biomedizinische NMR Forschungs GmbH, Max-Planck Insitut fuer biophysikalische Chemie, Goettingen, Niedersachsen, Germany, ²Dept. of Electrical Engineering and Computer Sciences, University of California, Berkeley, California, United States, ³Biomedizinische NMR Forschungs GmbH, Max Planck Institute, Goettingen, Niedersachsen, Germany

A novel chemical species separation method is presented. We repetitively switch a saturation pulse and acquire multiple images afterwards to get a global behavior, a paradigm, of the data. The correlation and significance of each pixel with the paradigm is calculated and used for visualization of the saturated species. The results are compared with conventional iterative decomposition of water and fat with echo asymmetry and least squares estimation (IDEAL), giving good agreement.

Markus Florian Untenberger¹, Martin Uecker², Sebastian Schaetz¹, Dirk Voit¹, and Jens Frahm^3
1Biomedizinische NMR Forschungs GmbH, Max-Planck Insitut fuer biophysikalische Chemie, Goettingen, Niedersachsen, Germany, ²Dept. of Electrical Engineering and Computer Sciences, University of California, Berkeley, California, United States, ³Biomedizinische NMR Forschungs GmbH, Max Planck Institute, Goettingen, Niedersachsen, Germany

In this abstract the extension of water-fat separation from static images to dynamic, real-time imaging is presented. We used a regularized nonlinear inverse image reconstruction on top of which an adapted iterative decomposition of water and fat with echo asymmetry and least squares estimation (IDEAL) was performed. Results from different anatomical views at different temporal and spatial resolutions are shown. Expected improvements from a model-based reconstruction and the extension to fat quantification are also discussed. The results show the feasibility of water-fat separation in real time.

Riad Ababneh¹, Thomas Benkert², Martin Blaimer², and Felix A. Breuer^2
1Physics, Yarmouk University, Irbid, Jordan, ²Research Center Magnetic Resonance Bavaria, Würzburg, Bavaria, Germany

We present a robust approach to separate fat and water signals in the abdomen during free breathing. The approach combined with a self-gated reconstruction of different respiratory phases in free-breathing. In this study a radial TrueFISP sequence was modified, wherein TE was made to vary between subsequent readouts. Good separation without streaking artifacts or blurring due to respiratory motion was obtained in all studied cases.

Abraam S. Soliman^1,2, Jing Yuan², Terry M. Peters^1,2, and Charles A. McKenzie^1,3
1Biomedical Engineering, University of Western Ontario, London, Ontario, Canada, ²Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada, ³Medical Biophysics, University of Western Ontario, London, Ontario, Canada

Several confounding factors can compromise the ability of MRI to accurately quantify fat, particularly B0 inhomogeneities and T2* decay. Recently, a labeling approach has been proposed to estimate B0 field variations in fat/water separation and was shown to outperform the widely-used region growing method. In this work, we extend this technique to 3D as well as integrate pixel-by-pixel calculation of T2* decay, necessary for accurate fat quantification. We demonstrate our approach on data for healthy volunteers and NAFLD patients.

Nadine Gdaniec¹, Tim Nielsen², Peter Börnert³, Holger Eggers², Mariya Doneva⁴, and Alfred Mertins^1
1University of Lübeck, Lübeck, Germany, ²Philips Research Laboratories, Hamburg, Germany, ³Philips Research Laboratory, Hamburg, Germany, ⁴Philips Research Europe, Hamburg, Germany

Breath-holding is an efficient strategy to minimize respiration induced artifacts in the abdomen if the patient’s capability is sufficient. The sampling pattern used deals with premature breathing onset by flexible scan termination. A temporally continuous compromise is made between SNR, undersampling aritifacts and resolution. This work aims at finding the optimal compromise by simulations on phantom experiments. To meet real clinical needs, dual-echo imaging was added for water-fat separation. The scan was complemented with a fast motion detection navigator that does not disturb the steady state and triggers automatic scan termination. Coil compression was applied for reduced reconstruction time.

Jedrzej Burakiewicz¹, Annette Jones², Sarah McWilliams², Jyoti Parikh², Hema Verma², Tobias Schaeffter¹, and Geoffrey David Charles-Edwards^1,2
1Biomedical Engineering, King's College London, London, United Kingdom, ²Guy's and St. Thomas' NHS Trust, London, United Kingdom

Separating silicone signal is an important issue in breast imaging, particularly when ruptures of the implant are suspected. Methods used up to date include either STIR or spectral suppression, or a combination of both. These however are susceptible to B0 inhomogeneities and can reduce signal strength. We present a combination of a 4-point IDEAL method with an optimised initial echo time,and with a region growing algorithm to provide a good initial estimate for the B0 map to efficiently separate water, fat and silicone signals; we also show first clinical results from a breast implant patient.

Yuji Iwadate¹, Anja C.S. Brau², Yoshihiro Tomoda³, Kenji Asano³, and Hiroyuki Kabasawa^1
1Global Applied Science Laboratory, GE Healthcare Japan, Hino, Tokyo, Japan, ²Global Applied Science Laboratory, GE Healthcare, Munich, DE, Germany, ³MR Engineering, GE Healthcare Japan, Hino, Tokyo, Japan

Multiecho water-fat separation with multifrequency fat spectrum modeling (IDEAL IQ) provides accurate estimates of fat fraction. Liver imaging is suitable for this technique, since fat is the hallmark feature of nonalcoholic fatty liver disease. However, respiratory motion often causes artifacts in liver imaging. We developed respiratory gated IDEAL IQ with navigator echo for free-breathing image acquisition. A navigator is inserted after imaging sequence and used for data acceptance/rejection. Navigator did not corrupt fat fraction calculation, and enabled free-breathing data acquisition with minimum motion related artifacts. This technique may be useful for patients who cannot hold their breath.

Sören Johst^1,2, Stephan Orzada^1,2, Anja Fischer^1,2, Lale Umutlu^1,2, Mark E. Ladd^1,2, and Stefan Maderwald^1
1Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany, ²Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany

Several different fat saturation (FS) techniques for single-shot fast spin echo (SSFSE) were compared at 7 Tesla, whereby the recently proposed Time Interleaved Acquisition of Modes (TIAMO) was used for the imaging portion of the sequence: A novel method using TIAMO (multiple fat-selective 90° RF pulses applied with alternating transmit RF modes), slice-selective gradient reversal (SSGR), and slice-selective smaller bandwidth refocusing pulses (SSB). SSGR performed best regarding FS, homogeneity of FS, and preservation of tissue signal intensity.

Robert Trampel¹ and Robert Turner^1
1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

Spin-echo and turbo-spin echo images of brain tissue displaying a strong contrast between grey and white matter are usually referred to as “T2-weighted”. However, since earlier studies show very little difference in T2 relaxation times between grey and white matter, the actual underlying contrast mechanism remains unclear. We therefore investigated the contrast obtained using a common spin-echo sequence at 7T with a range of sequence parameters. The results clearly show that T2 relaxation contributes hardly at all to the contrast obtained in brain tissue. Depending on the sequence parameters, variations in proton density, T1 relaxation, and magnetization transfer are the main sources of image contrast in common spin-echo imaging.

Flavio Carinci^1,2, Morwan Choli^2,3, Felix A. Breuer³, and Peter M. Jakob^2,3
1MRB Research Center, Wuerzburg, Germany, ²Department of Experimental Physics 5, University of Wuerzburg, Wuerzburg, Germany, ³Research Center Magnetic Resonance Bavaria e. V. (MRB), Wuerzburg, Germany

Magnetic resonance imaging of the lung is challenging due to low proton density, short T₂*, respiratory and cardiac motion. Single-shot turbo spin-echo (ssTSE) sequences can be used to obtain good signal-to-noise ratio in the lungs and to suppress motion artifacts. However preparation schemes such as diffusion and T₂* preparation can result in the violation of the CPMG conditions and generate severe artifacts. In this work we present the application of a non-CPMG ssTSE sequence to diffusion-weighted and T₂*-weighted imaging of the human lung. We show that this approach allows for apparent diffusion coefficient (ADC) and T₂* mapping of the human lung in a single 10s breath-hold.

Nicholas G. Dowell¹, Hannah van den Boomen², and Mara Cercignani^3
1CISC, Brighton and Sussex Medical School, Brighton, East Sussex, United Kingdom, ²Life Sciences, University of Sussex, Brighton, East Sussex, United Kingdom, ³CISC, Brighton & Sussex Medical School, Brighton, East Sussex, United Kingdom

Quantitative MT data is often not considered in imaging protocols due to the lengthy acquisition times that are required (up to 25 minutes). This is because the normal acquisition demand the collection of up to 12 gradient echo volumes. In response, a new approach, based on SSFP acquistion can dramatically cut acquisition times to less than 10 minutes. In this work, we rigorously compare the qMT data that is produced by both methods and assess whether the new SSFP method is a drop-in replacement for the established GRE approach.

Weiguo Li¹, Ning Jin², Tianjing Zhang¹, and Andrew C. Larson^1
1Radiology, Northwestern University, Chicago, Illinois, United States, ²Siemens Healthcare, Columbus, Ohio, United States

Respiratory self-gated magnetization transfer (RSG-MT) sequence was developed and applied to abdominal organs to generate magnetization transfer ratio (MTR) maps during free breathing (FB) of patients. Results showed that respiratory motion artifacts were significantly reduced and high quality MTR maps were generated. Future studies will evaluate the application of these RSG FB MT techniques for the assessment of liver fibrosis and tumor desmoplasia in clinical settings.

Sebastien Bär¹, Matthias Weigel¹, Valerij G. Kiselev¹, and Jochen Leupold^1
1Medical Physics Department of Radiology, University Hospital Freiburg, Freiburg, Germany

Simulations and experiments exploring the steady state signal amplitude dependency on the spoiler gradient in unbalanced gradient echo sequences and RF-spoiled gradient echo sequences are shown. Additionally, for these sequences and also under consideration of diffusion, signal evolution over the sequence repetition cycles is simulated for hyperpolarized nuclei in gas and liquid phase.

Joshua de Bever^1,2, Nick Todd², Mahamadou Diakite^2,3, and Dennis Parker^2
1School of Computing, University of Utah, Salt Lake City, Utah, United States, ²Utah Center for Advanced Imaging Research, Salt Lake City, Utah, United States, ³Physics Department, University of Utah, Salt Lake City, Utah, United States

This work evaluates the effectiveness of a 3D MRI pulse sequence for performing Acoustic Radiation Force Impulse imaging (ARFI) when applied in vivo. Building on 2D MR-ARFI techniques, this sequence provides enhanced volumetric coverage and would be especially beneficial for easily and safely localizing the ultrasound focal spot in all three dimensions before an MR guided high intensity focused ultrasound treatment.

Hanping Ke¹, Hao Chen¹, Zhiyong Zhang¹, Yanqin Lin¹, Zhong Chen¹, and Shuhui Cai^1
1Department of Electronic Science, Xiamen University, Xiamen, Fujian, China

In some cases, high-resolution NMR spectra are virtually impossible to obtain by conventional NMR methods because of intrinsic or extrinsic field inhomogeneity. In this study, spatial encoding intramolecular zero-quantum coherence (ZQC) technique was proposed to ultrafast achieve high-resolution NMR spectra under inhomogeneous fields. Theoretical analyses and experimental observations demonstrate that high-resolution NMR spectral information can be revived with two scans even when the field inhomogeneities are severe enough to erase most spectral information. This work may provide a new way to extremely enhance the acquisition efficiency of ZQC high-resolution spectroscopy for in vivo study of metabolites in organisms.

Honghao Cai¹, Xiaohong Cui¹, Shuhui Cai¹, and Zhong Chen^1
1Department of Electronic Science, Xiamen University, Xiamen, Fujian, China

The flavour and nutrition of a fish are greatly influenced by its fat content and its composition. However, it is difficult to obtain high-resolution (HR) NMR spectrum of intact fish tissues by traditional methods owing to the magnetic susceptibility gradients among the tissues. In this study, a Hadamard-encoded intermolecular multiple-quantum coherence (iMQC) method was implemented to obtain HR NMR spectrum of intact salmon muscle. The experimental results indicate that iMQC technique is a feasible way for HR NMR spectrum of fish tissues. Compared to magic angle spinning, it is non-invasive and suitable for in vivo and in situ applications.