Donglai Huo¹, and Xiaoli Zhao^1
1GE Healthcare, Waukesha, WI, United States

3DFSE sequence (CUBE) is widely used in clinical now. In this abstract, a new 3DFSE acquisition method called Cube Cx2 (Cube Contrast times 2) is proposed to acquire a 3D Cube T2 weighted and a 3D Cube T2 FLAIR weighted data simultaneously, all within the same scan time as the original Cube T2 FLAIR sequence. Scan time are greatly saved (a 3D T2 weighted dataset is free), and the resulting two perfectly registered 3D datasets could also be potentially used for other research fields.

Hahnsung Kim¹, Suhyung Park², Dong-Hyun Kim¹, and Jaeseok Park^3
1Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong, Seoul, Korea, Republic of, ²Medical Science, Yonsei University, Seoul, Korea, Republic of, ³Radiology, Yonsei University, Seoul, Korea, Republic of

We develop flip-angle single-slab 3D GRASE imaging, incorporating multiple echo planar imaging (EPI) readouts into a framework of turbo/fast SE imaging, to enhance the imaging efficiency without the direct trade off with SNR. To avoid the phase discontinuity induced problems, phase-independent image reconstruction is performed, in which each echo k-space is regenerated by GRAPPA-like parallel imaging technique employing within-and between- group k-space correlations and then averaged to retain SNR efficiency.

Masami Yoneyama¹, Masnobu Nakamura¹, Tomoyuki Okuaki¹, Takashi Tabuchi¹, and Junko Ogura^1
1Medical Satellite Yaesu Clinic, Tokyo, Japan

Magnetic resonance neurography is a useful technique with which to evaluate abnormal conditions of entire nerves and nerve bundles, and it has been used successfully in patients with tumors, trauma, and neuritis. In this study, we propose a new scheme of RARE (TSE) based fast high-resolution 3D volumetric peripheral nerve-sheath images using 3D nerve-SHeath signal increased with INKed rest-tissue RARE Imaging (3D SHINKEI). 3D SHINKEI technique combines fat-suppression prepulse, iMSDE�@preparation for suppression from vessels, and 3D variable refocusing flip-angle RARE readout segments for contrast-efficient T2-weighted images. Furthermore, iMSDE prepulse was based on T2-prep�@pulse; therefore, T2-contrast is affected by preparation duration.�@We attempt to use that characterization for muscle�@suppression. Consequently, 3D-SHINKEI technique was made possible to nerve-sheath depiction. 3D SHINKEI revealed detailed anatomy of lumbosacral plexus, brachial plexus, and cranial nerves. These results suggest that 3D SHINKEI can be used for fast high-resolution volumetric imaging of the peripheral nervous system.

Linqing Li^1,2, and Peter Jezzard^1,2
1FMRIB Centre, University of Oxford, Oxford, United Kingdom, ²Department of Clicical Neurosciences, University of Oxford, Oxford, United Kingdom

Flow-crushing bipolar gradient pairs are introduced into 2D TSE and 3D GRASE pulse sequences for black blood imaging multi-slice 2D or multi-slab 3D acquisition, termed as Bipolar 2D TSE and Bipolar 3D GRASE. Non-selective hard pulses used in conventional black blood modules are not required in these new imaging pulse sequences. Preliminary results indicate that the final average imaging speed has been increased dramatically up to 5 sec/slice or even faster (at least 2 or 3 times faster than conventional methods) with acceptable black blood imaging quality and comparable SNR.

Ryan Chamberlain¹, Steen Moeller¹, Curt Corum¹, Djaudat Idiyatullin¹, and Michael Garwood^1
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States

Sweep imaging with Fourier transform (SWIFT) is a novel 3D radial imaging technique that allows smooth and gradual gradient orientation changes during acquisition. Therefore, a SWIFT acquisition is nearly silent. A basic SWIFT sequence is proton density weighted due to low flip angles and very short echo times. It would be desirable to have a silent imaging technique that can create images with varying contrast. This work describes the use of SWIFT as a readout sequence with T₁ and T₂ preparation schemes, resulting in T₁- and T₂- weighted images acquired with minimal acoustic noise.

Petros Martirosian¹, Christina Schraml², Nina Franziska Schwenzer², Fabian Springer², Fritz Schick¹, and Michael Deimling^3
1Section on Experimental Radiology, University of Tübingen, Tübingen, Germany, ²Department of Diagnostic and Interventional Radiology, University of Tübingen, Germany, ³Department of Magnetic Resonance, Siemens Healthcare, Erlangen, Germany

Structure and composition of certain musculoskeletal tissues result in short T2 values and nearly lacking signal using conventional imaging sequences. In this work we aimed at improving the visualization of tendons, ligaments, and menisci by subtraction of two steady state free precession signals which were simultaneously acquired in a constant readout gradient. By means of strong asymmetric echo acquisition and short non-selective excitation RF-pulse providing an echo time 0.8 ms it was possible to visualize tendons, ligaments and menisci as hyperintense structures in the subtraction images. The presented sequence is a promising approach which is worth being evaluated in clinical musculoskeletal MR imaging.

Thomas Christen¹, Greg Zaharchuk¹, Nicolas Pannetier^2,3, Raphael Serduc^2,3, Nicolas Joudiou^2,3, Jean Claude Vial^2,3, Chantal Remy^2,3, and Emmanuel L Barbier^2,3
1Department of radiology, Stanford University, Stanford, California, United States, ²U836, INSERM, Grenoble, France, ³Grenoble Institut des Neurosciences, Grenoble, France

Using numerical simulations, we analyzed the influence of assumptions of a mathematical model on estimates of T2*, blood volume fraction (BVf) and blood oxygen saturation (StO2). Our results suggest that the static dephasing regime (water diffusion neglected) is a good approximation as long as vessel radii are above 3 µm and StO2 is below 80% at 3T. MR estimates of StO2 obtained using the total BVf are in good agreement with the StO2 averaged over arterial and venous compartments. According to the results obtained using microscopy data as microvascular geometry input, using straight cylinders to model blood vessels seems appropriate.

Pierre Bouzat^1,2, Thomas Christen^1,3, Sébastien Thomas^1,2, Nicolas Pannetier^1,4, Chantal Rémy^1,4, Jean-François Payen^1,2, and Emmanuel L Barbier^1,4
1U836, Inserm, Grenoble, France, ²CHU, Grenoble, France, ³Department of Radiology, Standford University, Standford, CA, United States, ⁴Grenoble Institut des Neurosciences, Université Joseph Fourier, Grenoble, France

To improve the accuracy and the spatial resolution of SO2MR maps obtained with quantitative BOLD approaches, an approach which combines a steady-state Blood Volume fraction measurement scheme, B0 and T2 mapping techniques, and a simpler mathematical model has recently been proposed. In this study, we evaluate the proposed acquisition scheme in healthy rats (n=17) while varying the inspired oxygen fraction and using a complete physiological control. We obtained a correlation between SO2MR and oxygen saturation measured in the sagital sinus of 0.84.

Thomas Christen¹, Benjamin Lemasson^2,3, Nicolas Pannetier^3,4, Regine Farion^3,4, Chantal Remy^3,4, Greg Zaharchuk¹, and Emmanuel L Barbier^3,4
1Department of radiology, Stanford University, Stanford, California, United States, ²Departments of Radiology, University of Michigan, Center for Molecular Imaging, Ann Arbor, Michigan, United States, ³Grenoble Institut des Neurosciences, Grenoble, France, ⁴U836, INSERM, Grenoble, France

We have analyzed how the addition of the transverse relaxation parameter (T2), the macroscopic field inhomogeneities (∆B0) and the blood volume fraction (BVf) to the estimates of magnetic resonance T2* influences the interpretation of BOLD oximetry results in a rat cerebral tumor model. We found no significant correlations between T2* and all other parameters in both tumor and healthy tissues. A lack of inclusion of any of these parameters may lead to incorrect assumptions about tumor oxygenation. Combining the parameters according to a quantitative BOLD approach leads to blood oxygenation (SO2) values independent of the initial T2* and consistent with previous measurements.

thomas christen¹, and Greg Zaharchuk^1
1Department of radiology, Stanford University, Stanford, California, United States

We have recently developed an MR method to measure the level of blood oxygenation (SO2) in the brain. The technique is based on extraction of the oxygenation information from T2* measurements using a mathematical model and measurements of T2, B0 and the cerebral blood volume (CBV). Although the studies in healthy rat brain have shown good results, the steady state approach used for the determination of CBV is yet only applicable in rodents. The objective of this study was to translate the method for human use. Estimates of MR_SO2 were obtained on healthy volunteers by combining ASL and PWI measurements.

Thomas Christen¹, Heiko Schmiedeskamp¹, Matus Straka¹, Roland Bammer¹, and Greg Zaharchuk^1
1Department of radiology, Stanford University, Stanford, California, United States

The objective of the study was to translate a quantitative BOLD approach originally designed to assess blood oxygenation in the rat brain into a clinical protocol. The technique is based on extraction of the oxygenation information from T2* measurements using a mathematical model and measurements of T2, B0 and the cerebral blood volume (CBV). We propose here to use an EPI multiple gradient and spin echo sequence to follow the bolus of a contrast agent. Baseline scans were used for T2*/T2 estimates whereas PWI was used to derive CBV maps. 4 healthy subjects and one stroke patient were scanned.

Julien Y BOUVIER^1,2, Irène TROPRES^3,4, Marjorie VILLIEN^1,5, Sylvie GRAND^1,6, Assia JAILLARD^4,6, Omer EKER^3,6, Olivier DETANTE^1,6, David CHECHIN², Jean-François LE BAS^3,6, Alexandre KRAINIK^1,6, and Emmanuel L BARBIER^1,5
1Grenoble Institut des Neurosciences, Université Joseph Fourier, Grenoble, France, ²Philips Healthcare, Suresnes, France, ³Université Joseph Fourier, Grenoble, France, ⁴IFR1, Grenoble, France,⁵U836, INSERM, Grenoble, France, ⁶CHU, Grenoble, France

A simple MR approach for local oxygen saturation (lSO2) assessment in human brain at 3T is evaluated. It combines separate estimates of T2, T2*, Blood Volume fraction (BVf) and B0 inhomogeneities. lSO2, BVf, T2 and T2* maps of four patients are presented. Mean lSO2 values in gray matter, white matter or both were 57±5%, 34±3%, and 45±4% respectively. This study shows that cerebral lSO2 may be measured with good spatial resolution in a short MR exam using three MR sequences. Further studies are required to validate this promising approach in human and improve the estimates obtained in white matter.

Deniz Ulucay¹, Judith Wild¹, Jessica Mende², Michael Dönnebrink³, Jürgen Finsterbusch⁴, Carsten Urbach¹, and Karl Maier^1
1HISKP, University of Bonn, Bonn, NRW, Germany, ²Lavandoo Mobile Solutions GmbH, Bonn, NRW, Germany, ³Medizin Center Bonn, Bonn, NRW, Germany, ⁴University Medical Center Hamburg-Eppendorf, Hamburg, Germany

Acoustic radiation contrast in magnetic resonance (ARC-MR) phase images is an innovative and recently developed method to visualize lesions and microcalcifications non-invasively based on differences in viscoelastic properties. Acoustic radiation force was applied using a custom made MR compatible piezoelectric transducer with a resonance frequency of 2.5 MHz. The thus produced displacement in breast tissue was made visible with a displacement sensitive spin-echo sequence. Measurements on three healthy volunteers show the feasibility of ARC-MR in human breast. It is expected that this method benefits breast cancer diagnostics by providing viscoelastic properties.

Alexey Tonyushkin¹, and Andrew M Kiruluta^1,2
1Physics, Harvard University, Cambridge, Massachussetts, United States, ²Radiology, MGH, Boston, Massachussetts, United States

Current approaches aimed at understanding brain function can be broadly divided into those that rely on hemodynamic responses as indicators of neural activity (fMRI, Optical and PET) and methods that measure neural activity directly (MEG and EEG). These approaches all suffer from poor temporal resolution (fMRI), poor spatial localization (MEG and EEG), or indirectly measuring neuron activity (fMRI, Optical and PET). It has been suggested that the proton spin population will be altered by neural activity fields resulting in a measurable effect on the MR signal that can be imaged by MRI methods. Unfortunately, this effect has been determined to be too small to be detectable. We present the physical basis and experimental evidence for an alternative approach based on a resonant interaction between the magnetic fields such as those arising from neuron activity, with a spin population that is undergoing Rabi oscillations at a frequency commensurate with the neuron currents. It is well established that neural firing during an activation has a spectrum associated with it.

Congbo Cai¹, Zhong Chen¹, Shuhui Cai¹, and Jianhui Zhong^2
1Departments of Physics and Communication Engineering, Xiamen University, Xiamen, Fujian, China, People's Republic of, ²Departments of Radiology and Biomedical Engineering, University of Rochester, Rochester, United States

Intermolecular multiple quantum coherences (iMQCs) possess some appealing unique properties for MRI. However, their intrinsic low signal to noise ratio prevents their widespread application. In this abstract, a new method was designed to produce a highly efficient localized distant dipolar field, thus substantially enhancing the iMQC signal intensity. Its application in MRI was tested. Experimental and simulation results indicate that the iMQC signal intensity is enhanced by more than two folds in comparison with the conventional CRAZED method.

Uvo Christoph Hoelscher¹, Steffen Lother¹, Florian Fidler¹, and Peter Jakob^1,2
1Research Center Magnetic Resonance Bavaria (MRB), Wuerzburg, Bavaria, Germany, ²Department for Experimental Physics 5 (Biophysics), University of Wuerzburg, Wuerzburg, Germany

Many medical problems can benefit from unambiguous localization and quantification of contrast agents, but conventional detection / quantification methods always require reference scans to separate contrast agent and tissue. In this work we present a new method to acquire both information without the need for a reference scan. The technique exploits relaxivity dispersion of the contrast agent making separation between contrast agent and tissue unambiguous. Resulting images show pure contrast agent signal and can be used to determine concentrations.

Craig Kenneth Jones^1,2, Alan J Huang^1,3, and Peter C M van Zijl^1,2
1FM Kirby Center, Kennedy Krieger Institute, Baltimore, MD, United States, ²Department of Radiology and Radiological Sciences, Johns Hopkins Medical Institutes, Baltimore, MD, United States,³Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States

Recently, chemical exchange saturation transfer (CEST) MRI has been used to detect the signals of mobile proteins and peptides in vivo through the exchange between amide protons and water protons. It is well known that mid to large size mobile macromolecules should experience cross-relaxation effects called Nuclear Overhauser Enhancements (NOEs), the build-up of which should be slower than exchange effects. In this work, exchange-relayed NOEs of mobile proteins are shown to be visible in CEST images in vivo. This is possible because a small B1 irradiation field was used to avoid competing effects from exchange and semi-solid magnetization transfer effects.

Luisa Ciobanu¹, Olivier Reynaud¹, Béchir Jarraya², and Denis Le Bihan^1
1NeuroSpin, CEA, Gif-sur-Yvette, France, ²NeuroSpin, INSERM-A VENIR unit, Gif-sur-Yvette, France

T2*-weighted imaging at ultra high magnetic field strengths benefits from a dramatic increase in contrast to noise ratio. We show that the vessels/tissue contrast in T2*-weighted images at 17.2 T is greatly influenced by the anesthetic agent used. Stemming from magnetic susceptibility differences, this phenomenon is visible to a much smaller extent at lower field strengths. We present high contrast T2* -weighted images of rodent brain microvasculature acquired in vivo, at 17.2 T under certain anesthesia conditions in the absence of contrast agents.

Tian Liu^1,2, Cynthia Wisnieff^1,2, Craig Horenstein³, Krishna Surapaneni³, and Yi Wang^1,2
1Biomedical Engineering, Cornell University, Ithaca, NY, United States, ²Radiology, Weill Cornell Medical College, New York, NY, United States, ³Radiology, Columbia University, New York, NY, United States

Calculation of susceptibility from measured field map is an ill-posed inverse problem. In addition, the noise on the field map may not be Gaussian in signal void regions or due to improper phase unwrapping, complicating the inversion. In this abstract, we propose to use an Iteratively Reweighted Least Square (IRLS) algorithm to automatically identify the outlier pixels with non-Gaussian field noise, and attenuate the weighting for these pixels. Preliminary results showed that IRLS is able to suppress streaking artifacts in the presence of clusters of outlier pixels.

Philipp Ehses¹, Xavier Helluy¹, Michael Völker¹, Vikas Gulani², Nicole Seiberlich², Mark A Griswold², Peter M Jakob^1,3, and Felix A Breuer^1
1Research Center for Magnetic Resonance Bavaria (MRB), Würzburg, Germany, ²Dept. of Radiology, University Hospitals of Cleveland and Case Western Reserve University, Cleveland, United States, ³Dept. of Experimental Physics 5, Universität Würzburg, Würzburg, Germany

Quantitative MRI has not yet found widespread clinical adoption, mainly due to long scan times required to map the various parameters of interest. PCA has previously been used to reconstruct data from an undersampled time series, and it has been demonstrated that relaxometry dynamics can be well described by a small number of principal components. In this work, we present a novel PCA based reconstruction method, which allows the quantification of T₁, T₂ and spin-density from a single IR TrueFISP experiment in under 5s per slice. Undersampling artifacts were completely removed and the results were comparable to a fully-encoded reference.

Weiqiang Dou¹, Ralf Deichmann², Oliver Speck¹, and Kai Zhong^1
1Biomedical Magnetic Resonance, Otto-von-Guericke University, Magdeburg, Saxon-Anhalt, Germany, ²Brain Imaging Center, Johann Wolfgang Goethe-University Frankfurt/M., Frankfurt/Main, Hesse, Germany

Strong B0 field inhomogeities at 7T can decrease significantly brain T2* values that are related to brain tissue iron content. An improved correction method considering both linear and quadratic B0 variations was described and implemented in this study. The results showed significant improvement on T2* values compared to that of the linear correction method at intermediate susceptibility gradients (50 – 150 T/m). The new method therefore allow for more reliable T2* mapping for 7T in vivo studies.

Julia V Velikina¹, Samuel A Hurley¹, Andrew L Alexander¹, and Alexey A Samsonov^1,2
1Medical Physics, University of Wisconsin - Madison, Madison, WI, United States, ²Radiology, University of Wisconsin - Madison, Madison, WI, United States

We propose a novel way to accelerate multi-component relaxometry by a factor of 4 by applying variable density undersampling in the flip angle dimension of the acquired SPGR and bSSFP data and then reconstructing the obtained incomplete data sets using constrained reconstruction in the parametric (flip angle) dimension. Finally, parameter maps, such as myelin water fraction, are derived from the reconstructed image series. We compare our results with the ones obtained using parallel imaging alone and fully sampled data.

Tilman Johannes Sumpf¹, Martin Uecker¹, Susann Boretius¹, and Jens Frahm^1
1Biomedizinische NMR Forschungs GmbH, Goettingen, Germany

Quantitative evaluations of the T2 relaxation time are of high importance for diagnostic MRI. Standard T2 mapping procedures rely on the time-demanding acquisition of fully sampled k-space datasets at multiple echo times. Recently, a nonlinear inverse reconstruction method has been proposed which allows for reconstructions of spin-density and T2 maps from highly undersampled radial data. Here, we extended this concept for Cartesian acquisition schemes and even for settings without parallel imaging. An automatic scaling procedure as well as a dedicated undersampling pattern minimize residual artifacts. The approach is validated for T2 mapping of a numerical phantom and the human brain.

Nicole Seiberlich¹, Dan Ma², Philipp Ehses³, Vikas Gulani¹, and Mark Griswold^1,2
1Radiology, University Hospitals of Cleveland, Cleveland, OH, United States, ²Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States, ³Research Center for Magnetic Resonance Bavaria (MRB), Wuerzburg, Germany

Orthogonal Matching Pursuit (OMP) has emerged as a powerful tool for the quantification of MRI relaxation parameters, where a dictionary of simulated signal evolution curves (atoms) is compared with undersampled images in order to determine relaxation parameter maps. When working with multiple parameters (quantifying T1, T2, and M0 simultaneously), atoms can be quite similar, making OMP quantification inaccurate. Using an approach that considers the average correlation instead of simply the highest correlation, we show that the relaxation parameters can be more accurately determined. Average correlation OMP is demonstrated using IR-TrueFISP to yield accurate T1 and T2 maps in abdominal imaging.

Ives R Levesque¹, Nikola Stikov², G Bruce Pike², and John M Pauly^1
1Electrical Engineering, Stanford University, Stanford, CA, United States, ²Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada

Drift in the signal of MT-weighted short-TR GRE sequences has been observed in quantitative MT experiments at two different sites. Signal decreases of 2-6% were observed over the course of data acquisitions in phantoms and in vivo. Drift appears to depend on the duration of the acquisition and on the MT pulse characteristics. The drift likely affects QMTI parameter estimates, in a manner dependent on the experimental method. We present our investigation into this effect, and discuss potential causes including B1 drift related to RF amplifier and/or coil performance, and temperature-related T1 increases.

Bernhard Neumayer¹, and Rudolf Stollberger^1
1Institute of Medical Engineering, Graz University of Technology, Graz, Steiermark, Austria

The method of phase acquisition of composite echoes (PACE) is used to additionally quantify BPF by applying a non-linear parameter identification and therefore gaining information on the separate components of the acquired signal. Extrapolation of the stimulated echo component for measurements with T_M>100ms yields S₀/(1+f) which in combination with S₀ acquired using a minimum possible T_M allows for quantification of the bound pool fraction BPF additionally to the T₁ quantification provided by the phase information. The method was validated using BSA phantoms with concentrations ranging from 10 to 30% of BSA to water per weight and provided a linear relationship of BPF and BSA concentration.

Monika Gloor¹, Klaus Scheffler¹, and Oliver Bieri^1
1Radiological Physics, University of Basel Hospital, Basel, Switzerland

Recently, it has been shown that fast magnetization transfer (MT) scans based on balanced steady-state free precession (bSSFP) with RF pulse modification achieve high SNR and high reproducibility at 1.5T. At 3T, combination of multiple, phase-cycled, bSSFP scans might be required to overcome limitations from off-resonance artifacts. In this study, different recombination methods for the generation of accurate magnetization transfer ratio (MTR) maps were analyzed. Maximum intensity projection removes off-resonance artifacts without significant MTR modification, whereas sum-of-squares and weighted-combination bSSFP yield reduced MTR values.

Rebecca Sara Samson¹, Matthew Clemence², Xavier Golay³, and Claudia A M Wheeler-Kingshott^1
1Department of Neuroinflammation, UCL Institute of Neurology, London, England, United Kingdom, ²Philips Clinical Science Group, Philips Healthcare, Guildford, England, United Kingdom, ³UCL Institute of Neurology, United Kingdom

RF B₁ transmit field non-uniformity, caused primarily by skin depth and dielectric resonance effects, is a large source of error in quantitative MR measurements made at 3.0T. We investigated the possibility that B₁ errors could be reduced using dual transmission by measuring cervical cord MTR and B₁ with and without dual transmission. Preliminary data acquired on three healthy subjects indicates that it may be possible to reduce inter-subject variation in whole cord MTR histogram peak locations using dual transmission at 3.0T. This could be an important consideration when designing future long-term clinical studies using quantitative MRI outcome measures.

Richard D Dortch^1,2, Jay Moore^2,3, Marcin Jankiewicz^1,2, Adrienne N Dula^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, ²Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States, ³Physics and Astronomy, Vanderbilt University, Nashville, TN, United States

Quantitative MT (qMT) imaging yields indices describing the interactions between free water and immobile macromolecular protons. Previous work at 1.5 and 3T has indicated that certain qMT indices may be sensitive to myelin content in white matter. Such studies may benefit from the increased SNR available at 7T; however, they are currently hampered by significant ΔB₀ and B₁⁺inhomogeneities. Therefore, we have developed a selective inversion recovery (SIR) qMT protocol at 7T that addresses these issues and here we report data acquired in healthy human brain. The resulting qMT parameters at 7T were in agreement with previously published values.

Hung Phi Do¹, Robert Marc Lebel², and Krishna S Nayak^2
1Department of Physics & Astronomy, University of Southern California, Los Angeles, California, United States, ²Department of Electrical Engineering, University of Southern California, Los Angeles, California, United States

Wideband SSFP is an alternating-TR sequence that suppresses much of the off-resonant banding artifacts associated with balanced SSFP. In this study, we demonstrate that wbSSFP is more sensitive to magnetization transfer (MT) than is bSSFP at all tip angles and RF pulse durations, making this sequence attractive for mapping the MT ratio or for imaging applications where strong MT weighting is desired.

Miriam Rabea Kubach¹, Kaveh Vahedipour¹, Tony Stoecker¹, and N. Jon Shah^1,2
1Forschungszentrum Juelich, Institute of Neuroscience and Medicine, Juelich, NRW, Germany, ²Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany

Precise and accurate T1 mapping in the presence of MT requires modifications of the fitting model to account for the exchange. If those are neglected and the standard models are applied, an error in the T1 values is inevitable. Our work aims to quantify this error for different T1 mapping methods based on simulations of white and grey matter. The effects of SNR and MT on the precision and accuracy of T1 mapping was studied.

Jack T Skinner^1,2, Todd E Peterson^2,3, and Mark D Does^1,2
1Biomedical Engineering, Vanderbilt University, Nashville, TN, United States, ²Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States, ³Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States

A simple, two-measurement method for inverting a two-pool model with water exchange is presented. T₂ measurements of injured rat skeletal muscle were made before and after contrast agent injection, from which estimates of the intrinsic extra-cellular volume fraction were computed and found to correlate strongly (R² = 0.71) with estimates derived from SPECT imaging of an extra-cellular radiotracer.

Christopher David James Sinclair^1,2, Jasper M Morrow¹, Michael G Hanna¹, Mary M Reilly¹, Tarek A Yousry^1,2, Xavier Golay², and John S Thornton^1,2
1MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, United Kingdom, ²Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, London, United Kingdom

We evaluate a scheme for correcting RF inhomogeneities in skeletal muscle magnetization transfer ratio (MTR) maps using B1 mapping data. A quantitative model of pulsed MT is used to demonstrate the applicability of the scheme to muscle and we perform automatic segmentation using T1 maps. We demonstrate experimentally that the correction scheme reduces the within- and between- subject variation of muscle MTR measures in 28 healthy volunteers and 23 patients with neuromuscular conditions. Reductions in instrumental inhomogeneities improve the potential of MTR as quantitative marker of disease, which has been shown previously to correlate with clinical disease status.

Amir Eissa¹, and Alan H. Wilman^1
1University of Alberta, Edmonton, Alberta, Canada

A new class of 3D Cartesian MRI is introduced whereby the voxel encoding orientation is independent of the imaging slab orientation. The excitation region can be chosen for the optimal region of interest, while the encoding direction can be arbitrarily oriented for ideal voxel alignment. The resulting aliased image can be easily unwrapped to produce standard image depiction. The method is particularly useful with anisotropic voxels, enabling voxel alignment to produce minimal blurring of oriented fine structures, while maintaining ideal volume placement. For phase susceptibility methods, the method enables oblique imaging with voxel orientation maintained along the main field direction.

Andre de Oliveira¹, Tobias K Block¹, and Stephan Kannengiesser^1
1Siemens AG, Erlangen, Germany

In MRI exams, focus is often given to a specific pathologic region (eg.: prostate, liver, brain) and in most cases the field of view (FOV) is centred at the region to be analysed. Here we propose a a new acquisition technique where 2D RF pulses to are employed and the RO direction is rotated for each individual average, allowing image acquisition with high central SNR (the same SNR as acquired with the actual protocols using 2D RF pulses) and increased FOV.

Ning Jin¹, Yang Guo², Jie Deng³, and Andrew C Larson^1,4
1Departments of Radiology and Biomedical Engineering, Northwestern University, Chicago, IL, United States, ²Department of Radiology, Northwestern University, Chicago, IL, United States,³Department of Medical Imaging, Children's Memorial Hospital, Chicago, IL, United States, ⁴Robert H. Lurie Comprehensive Cancer Center, Chicago, IL, United States

Quantitative R2 and R2* maps are critical for a wide range of applications. The GESFIDE sequence can provide simultaneous R2 and R2* information. However, for abdominal imaging, application of this method can be particularly challenging due to respiratory motion. We developed a GESFIDE-PROPELLER approach for simultaneous R2 and R2* measurements in the abdomen and demonstrated that GESFIDE-PROPELLER can provide accurate R2 and R2* measurements while reducing respiratory motion artifacts.

Guillaume Gilbert^1,2, Geneviève Savard¹, Céline Bard¹, and Gilles Beaudoin^1
1Department of Radiology, Centre Hospitalier de l'Université de Montréal, Montreal, QC, Canada, ²MR Clinical Science, Philips Healthcare, Cleveland, OH, United States

In this abstract, the use of a multi-echo gradient-echo sequence is investigated as a way to improve the contrast-to-noise ratio for susceptibility weighted phase imaging, which is often used to assess brain iron deposition. In comparison to the standard approach using a single-echo sequence, it is shown that the use of the proposed method allows for a significant reduction of the noise contribution in the reconstructed susceptibility weighted phase image, while preserving both contrast and acquisition time.

Nicholas Ryan Zwart¹, and James Grant Pipe^1
1Neuroimaging Research, Barrow Neurological Institute, Phoenix, Arizona, United States

Signal to noise ratio gains in low VENC phase contrast MRI are limited by the ability to successfully unalias phase measurements that fall outside the -180 to 180 degree interval. The ability to unalias phase measurements on a per pixel basis is limited by errors in the measurements due to noise and signal biased phase. The method presented in this work is the combination of a multiple low VENC acquisition strategy and reconstruction algorithm that produces time efficient SNR in phase contrast MRI.

Patrick H Le Roux¹, Graeme C McKinnon², Yi-Fen Yen³, and Brice Fernandez^4,5
1Applied Science Lab, GE Healhtcare, Palaiseau, France, ²Applied Science Lab, GE Healthcare, Waukesha, WI, United States, ³Applied Science Lab, GE Healthcare, Menlo-Park, CA, United States,⁴Applied Science Lab, GE Healhtcare, Nancy, France, ⁵IADI Lab, INSERM, Nancy, France

We present the first direct experimental proof of nCPMG capability to refocus the magnetization at the end of a long echo train. The nutation angle used is small enough (130°) to make a large difference between a sequence where realignment is used and a sequence where only stabilization is used. Also measuring the two transverse components insure the third one is also refocused, and that there is truly no initial phase dependence.

Andre Jesmanowicz¹, Andrew S. Nencka¹, and James S. Hyde^1
1Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States

The addition to SENSE of spatial variation of the magnetization phase doubles the number of useful non-singular equations in the method. Phase encoded SENSE (P-SENSE) described here can be used without the need for spatial variation of coil sensitivities. An acceleration factor of up to 2 can be achieved in a single-coil MRI environment.

Shuhui Cai¹, Can Wu¹, Zhiyong Zhang¹, and Zhong Chen^1
1Department of Physics, Fujian Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, Fujian, China, People's Republic of

Ultrafast methods based on spatial encoding enable 2D and mD acquisition to be completed within a single scan and thus greatly shorten the experimental time. In this abstract, we proposed an ultrafast pulse sequence for acquiring high-resolution 2D SECSY spectrum in inhomogeneous fields. Absolute chemical shift and J-coupling information can be obtained. It works particularly well in the inhomogeneous fields where z-orientation inhomogeneities are dominant.

Xianfeng Shi^1,2, Young-Hoon Sung^1,3, SeongEun Kim², Perry Renshaw^1,3, and Eunkee Jeong^2
1The Brain Institute, University of Utah, Salt Lake City, Utah, United States, ²Department of Radiology, University of Utah, Salt Lake City, Utah, United States, ³Department of Psychiatry, University of Utah, Salt Lake City, Utah, United States

Creatine Kinase (CK) is widely present in human brain tissues. It catalyzes the conversion between phosphocreatine (PCr) and adenosine diphosphate (ATP). Thus CK reaction rate constant (k_f) is an indicator of the brain neuronal activity. A method using ISIS and a saturation recovery process provides accurate measurement of k_f within 40 minute data acquisition, which is mostly spent to measure the apparent T1 relaxation time. The long acquisition time prevents its routine application. In this report, a new pulse sequence “ISIS with simultaneous spin echo and stimulated Echo (ISIS-sSESTE)â€� is developed to rapidly measure the ³¹P T₁ relaxation time.

Patrick Michael Heiler¹, Benedikt Rieger¹, Philipp Krämer¹, Simon Konstandin¹, and Lothar Rudi Schad^1
1Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany

During the long phase encoding of sodium CSI measurements, due to hardware constraints on common whole-body scanners, signal significantly decays meanwhile no data acquisition is possible. Thus, the presented work describes a 3D chemical shift imaging (CSI) sequence with individually minimized phase encoding durations for sodium MRI. In an additional experiment, CSI data is acquired with a Hanning weighted pre-filter and both approaches are compared to the radial projection imaging technique.

Rajakumar Nagarajan¹, Jonathan Furuyama¹, Daniel Margolis¹, Steven Raman¹, Manoj Kumar Sarma¹, and Michael Albert Thomas^1
1Radiological Sciences, University of California Los Angeles, Los Angeles, California, United States

Prostate cancer (PCa) is associated with lower levels of citrate (Cit) and higher levels of choline (Cho) than those in benign prostatic hyperplasia or healthy prostate tissues. Due to the overlap of Cho with creatine resonances, it is difficult to measure spermine resonances in the prostate clearly by single-and multi-voxel based one-dimensional spectroscopic imaging. We have implemented and evaluated the novel echo-planar imaging based four dimensional (4D) MRSI sequences (J-resolved spectroscopic imaging (EP-JRESI) and correlated spectroscopic imaging (EP-COSI)) in the prostate using 3T MRI scanner. The pilot findings in six healthy males using the external phased-array matrix will be presented.