Debra Strick Rivera¹, Carsten Koegler¹, and Robert Turner^1
1Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

Cable radiation reduces effective transmit power. Radiated power increases with the fourth power of frequency, and can therefore be detrimental to UHF transmit arrays. Baluns can improve voltage balance across transmit coils, and thereby reduce cable radiation. Amplitude balance, phase balance, and common-mode rejection ratio were introduced as simple quantitative methods. Wide-band and narrow-band 180° baluns were analyzed. Performance of narrow-band baluns was dramatically improved through amplitude and phase matching measurements. Transmit efficiency was characterized in the scanner from flip-angle maps. The addition of 180° baluns improved transmit power efficiency between 10% (on average) and over 50% at 7T.

Frederick H. Raab¹, Martin C. Poppe², and Daniel P. Myer^3
1Green Mountain Radio Research Company, Colchester, VT, United States, ²Poppe Associates, ³Communication Power Corporation

This amplifier system is based upon the Kahn EER (envelope-elimination-and-restoration) technique. The amplifier system incorporates class-E RF-power amplifiers, class-S modulators, and a digital signal processor. The DSP includes capability for generating stored signals as well as digitizing and amplifying low-level analog RF inputs. The module incorporates four RF-power amplifiers and can produce up to 750 W with an overall efficiency of 70 percent. It has a bandwidth of 250 kHz and an envelope rise time of 1 s, and can be configured for operation between 10 and 128 MHz.

John T Vaughan¹, and Daniel Myer^2
1University of Minnesota, Minneapolis, MN, United States, ²CPC

RF power amplifiers can be mounted on the coil, in the magnet for improved efficiency and lower cost.

Oliver Heid¹, and Timothy Hughes^1
1Corporate Research, Siemens AG, Erlangen, Bavaria, Germany

Silicon Carbide JFETs promise to revolutionize RF power generation up to UHF frequencies. The main advantages are extremely high efficiency, power density and the absence of RF load matching requirements. We report on the design and testing of a 11kW prototype RF transmitter module.

Barbara L Beck^1,2, Sien Wu³, Walker J Turner³, Rizwan Bashirullah³, and Thomas H Mareci^2,4
1McKnight Brain Institute, University of Florida, Gainesville, FL, United States, ²National High Magnetic Field Laboratory, Tallahassee, FL, United States, ³Electrical and Computer Engineering, University of Florida, ⁴Biochemistry and Molecular Biology, University of Florida

MR coil-impedance matching for in vivo animal studies in high field, small diameter, horizontal bore magnets is a time consuming and challenging procedure due to limited space and large frequency shifts from sample loading. We developed a High-Q input circuit attached to an automatic impedance matching system that optimizes, within seconds, the tuning and matching of a single-frequency coil. The procedure can be performed with the animal in the magnet, negating the need for laborious manual tuning, while at the same time, reducing the stress on the animal. Comparison to a coil with discrete components demonstrates equivalent SNR.

Robert H Caverly¹, William E Doherty², and Ronald Watkins^3
1ECE, Villanova University, Villanova, PA, United States, ²Microsemi-Lowell, ³Radiology, Stanford University

The time domain simulation techniques outlined in the abstract will help MR engineers to optimize the parameters of TR switching and to help improve minimum echo time. The work will help MR engineers pick the appropriate PIN diode for their TR switching applicaiton.

Victor Taracila¹, Aleksey Zemskov¹, Miguel A Navarro¹, Vijayanand Alagappan¹, and Fraser Robb^1
1GE Healthcare, Aurora, Ohio, United States

One of the subsets of inductive decoupling is the so-called transformer decoupling, which in fact represents a remote inductive decoupling. It is used when overlapping between elements is not desired due to possible sensitivity overlap that affects the g-factor in accelerated imaging. The traditional transformer used in MRI coils is built out of inter-woven or adjacent inductors sharing a common axis. One of the disadvantages of this type of transformer is the difficulty of adjustment of the coupling, dimensions and possible inductive coupling to other inductors in the MRI system. In this work we propose a transformer based on “RF Invisible” inductors shape with adjustable inductive coupling strength and no self-inductance, which is very handy for MRI coil design and applications.

Sergei Obruchkov¹, William O'Reilly², and Arsen Hajian^3
1University of Waterloo, Waterloo, ON, Canada, ²Tornado Medical Systems, Toronto, ON, Canada, ³Systems Design Engineering, University of Waterloo, Waterloo, ON, Canada

Digital receiver technology is relatively a new comer to the field of MRI and it offers great opportunity for customization and research. The purpose of our work was to show how developments in digital communication technology may be used to used as MR receiver chains such that each receive channel is optimized to acquire data from an individual coil in the phased array. The findings showed that by decreasing receiver bandwidth and digital filtering it is possible to reduce noise power, thus by matching receiver channel to individual coil signal from phased array coils could be optimized.

Walker J. Turner¹, Barbara L. Beck², Sien Wu¹, Thomas H. Mareci³, and Rizwan Bashirullah^1
1Electrical and Computer Engineering, University of Florida, Gainesville, FL, United States, ²McKnight Brain Institute, University of Florida, ³Biochemistry and Molecular Biology, University of Florida

This RF front-end circuitry is designed for clock and data extraction from wirelessly transmitted RF pulses for use in controlling the resonance of an implantable receiver coil with a digitally controlled capacitor array intended for monitoring an implanted artificial pancreas. The fabricated chip measures 650um by 450um and demonstrates the capability of data/clock recovery. The design is compatible with current NMR console technology and can be further integrated for in vivo operation.

Ye Li¹, Yong Pang¹, and Xiaoliang Zhang^1,2
1Department of Radiology and Biomedical Imaging, Univerisity of California San Francisco, San Francisco, California, United States, ²UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco, California, United States

We propose a CMDM design of quadrature transmit/receive surface coil at 7T. A prototype coil was fabricated. Bench test and MR phantom experiments were carried out to evaluate the coil performance. Our results show that the common-mode and differential-mode are decoupled sufficiently at 300MHz range due to the intrinsic decoupling of the two modes. SNR improvement is achieved in the whole region of interest. The CMDM coil is feasible for parellel imaging. The proposed method is an efficient, robust and simple approach to increase the SNR of surface coils as well as surface coil elements in array coils.

Yoshihisa Soutome¹, Yosuke Otake¹, and Yoshitaka Bito^1
1Central Research Laboratory, Hitachi Ltd., Kokubunji, Tokyo, Japan

We have developed a new decoupling method using a vertical loop for gapped phased-array coils. The vertical loop is placed between nearest-neighbor coils, and by changing the value of the capacitor in the vertical loop, decoupling can be easily achieved. We also fabricated a 3.0T 2-ch loop array with vertical loop and demonstrated its decoupling performance. The coupling S12 measured between the two coils was −28 dB. Phantom images showed no significant coupling between the coils. These results indicate that the proposed method can effectively decouple between the nearest-neighbor coils in gapped phased-array coils.

Bing Wu¹, and Xiaoliang Zhang^2,3
1Coil Engineering, GE Healthcare, Wauehsha, WI, United States, ²Radiology and Biomedical Imaging, UCSF, ³UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco, CA, United States

Transformer or capacitor is often required to electromagnetically decouple the gapped loops, non-adjacent loops, or microstrip resonators in RF coil arrays when conventional coil overlapping is not applicable. In this abstract, we analyze the general L/C decoupling circuits and suggest the use of inductor for decoupling at high fields. Based on the circuit analysis, a new inductive decoupling method is proposed for designing microstrip arrays at high magnetic fields.

Andreas Peter¹, and Jan G. Korvink^1,2
1Department of Microsystems Engineering - IMTEK, University of Freiburg, Freiburg, Germany, ²Freiburg Institute of Advanced Studies (FRIAS), University of Freiburg, Freiburg, Germany

We present the design and optimisation of a novel single and dual-stage low-Z LNAs for 3 T, 7 T and 9.4 T. Cascaded two-port networks represent the small-signal behaviour of the LNA. Matlab is used to optimise the component values to fulfil the desired matching conditions at the input and the output of the LNA together with a minimal noise figure, a maximum gain and unconditional stability. A gain of 38 dB together with a noise-figure of 0.3 dB was achieved at 7 T.

Elmar Fischer¹, Andreas Peter², Daniel Sonner³, Hermann Massler³, Jan G Korvink^2,4, Jürgen Hennig¹, and Maxim Zaitsev^1
1Radiology, University Medical Center Freiburg, Freiburg, Germany, ²Microsystems Engineering – IMTEK, University of Freiburg, Freiburg, Germany, ³Hochfrequenz-Bauelemente und -Schaltungen, Fraunhofer IAF, Freiburg, Germany, ⁴Freiburg Institute of Advanced Studies (FRIAS), University of Freiburg, Freiburg, Germany

This work is on the implementation of miniaturized two-stage preamplifiers for 9.4 T (400 MHz), intended to be used for each coil, respectively, in multi-parallel receive array coils. Amplifier performance has been tested successfully with signals of up to eight coils of a receive array with eight preamplifiers in parallel. Amplifier performance could be verified for magnetic fields up to 9.4 T.

Cecilia Possanzini¹, Phil van Liere¹, Hans Roeven¹, Jan den Boef¹, Charlie Saylor², Jan van Eggermond¹, Paul Harvey¹, and Elisabeth Moore^1
1Philips Healthcare, Best, Netherlands, ²Invivo Corp., Gainsville, Florida, United States

This work describes a scalable digital broadband receive system architecture which no longer limits the number of receive channels that can be connected and provides a consistent signal fidelity independent of the number of channels. In this study, we show that in this architecture increasing the ‘channel count’ of the system is simply achieved by placing additional coils on the patient support, without modifying anything on installed receive chain of the system as for traditional analog architecture.

Russell Lagore¹, Brodi Roberts¹, B. Gino Fallone^1,2, and Nicola De Zanche^1,2
1Dept. of Oncology, University of Alberta, Edmonton, Alberta, Canada, ²Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada

Three preamplifier technologies are compared at various B₀ field strengths, highlighting sensitivity to changes in noise figure and input impedance.

Taner Demir¹, Lance DeLaBarre², Burak Akin¹, Gregor Adriany², Kamil Ugurbil², and Ergin Atalar^1
1National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Ankara, Turkey, ²Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, United States

In this work, we introduce an optical transmission system for a 3T and a 7T system. The transmission system reduces the interconnection problems between large number of coil elements and the scanner and possibly enhances RF safety. The system transmits the analog MRI and detuning signals optically. In order to demonstrate the performance of the system, phantom and human experiments are performed.

Boris Keil¹, Veneta Tountcheva¹, Christina Triantafyllou^1,2, and Lawrence L Wald^1,3
1A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States, ²McGovern Institute for Brain Research, MIT, Cambridge, MA, United States, ³Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, United States

An intentionally mistuned approach was tested as a simple additional decoupling method for array coils. To address this issue, we exploit a phenomena associated with preamplifier decoupling, which allows array coil element to be tuned off-resonance from the Larmor frequency without significant degradation of SNR. This approach can potentially facilitate decoupling in arrays with high element coupling, especially in flexible arrays where geometric decoupling from overlap or shared impedances is not feasible for all positions of the flexing former.

Lou Poulo¹, Robert Haefner¹, Bernd Stoeckel², Cem Murat Deniz³, Leeor Alon³, Daniel K Sodickson³, and Yudong Zhu^3
1Analogic Corporation, Peabody, MA, United States, ²Siemens Medical Solutions USA Inc, New York, NY, United States, ³Center for Biomedical Imaging, Department of Radiology, NYU School of Medicine, New York, NY, United States

The development and initial testing of a complete 7T, 32-channel RF transmit system is described. This RF subsystem, consisting of a new RF sequencer/controller, independent waveform generation, and power amplifiers, is designed to be an add-on expansion to an existing 7T imager. The new RF capability will enable research into the tradeoffs in the various questions/tradeoffs relating to the number of available channels. The system is modular in 8-channel increments, and the architecture allows relatively straightforward integration into most scanners

Wolfgang Loew¹, Randy Giaquinto¹, Laura Sacolick², William Allyn Grissom², and Mika Vogel^2
1Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States, ²GE Global Research Europe, Germany

To increase homogeneity of the transmit field at 3 Tesla an 8-channel transceiver system implementation is presented. Shorter distance to the imaging object reduces the amount of power needed for a desired B₁ field in the object. The system consists of an 8-channel head T/R-coil, 8 modified GE T/R-switches, and 8 high power bias tees. Imaging experiments were performed in-vivo with this setup and B₁ magnitude and phase maps were acquired.

Bing Wu¹, Haidong Peng¹, Dan Xu¹, and Liang Xuan^1
1GE Healthcare, Waukesha, WI, United States

Through the study on a commercial 32ch coil, we find that the channel number can be reduced from 32 to 24 without degrading its SNR and parallel imaging performance. Reduced losses from coil components, reduced cost and increased stability are then expected.

Christian Findeklee¹, Randy Duensing², and Arne Reykowski^2
1Philips Research Laboratories, Hamburg, Hamburg, Germany, ²Invivo, United States

The effect of element coupling in receive arrays has been investigated for a long time. With new insights into noise coupling and array noise matching, we now can quantify this SNR reduction. Optimized matching is able to avoid SNR reduction for a target location; however, it may still yield significant SNR-loss in other areas. In our experiments, we demonstrate how inductive decoupling can increase the area of high SNR.

Aurelien F Stalder¹, Zhi Yuan Dong¹, Yang Qi¹, Jelena Bock², Jürgen Hennig², Michael Markl², and Kun Cheng Li^1
1Dept. of Radiology, Xuanwu Hospital of Capital Medical University, Beijing, China, People's Republic of, ²Dept. of Radiology - Medical Physics, University Hospital Freiburg, Germany

4D flow-sensitive MRI was performed in the thoracic aorta of 11 healthy volunteers at 3T using 12- and 32-channel coils and parallel imaging (GRAPPA) with accelerations R=2 and R=3. SNR, velocity divergence and streamlines length quantification as well as semi-quantitative image grading was performed to assess data quality. R=3 allowed to save 19.5±5% measurement time compared to R=2 (14.2±2.4 min). 12 channels with R=2 and 32 channels with R=3 produced data with significantly higher quality compared to 12 channels and R=3. There was no significant difference between 12 channels with R=2 and 32 channels with R=3 but for the depiction of supra-aortic branches where the 32-channel coil was superior.

Petrice Marie Mostardi¹, Eric G Stinson¹, Thomas C Hulshizer¹, Phillip J Rossman¹, and Stephen J Riederer^1
1MR Research Laboratory, Mayo Clinic, Rochester, MN, United States

Currently there is no coil that allows for 2D acceleration over the entire head and neck. The purpose of this work was to develop a multi-element receiver coil array that has high SNR and the capability for high (R =4-8) 2D SENSE acceleration from the head through the upper torso. The coil design consists of a newly developed neck/torso array which is used in combination with the clinical 8HRBRAIN coil. The neck/torso array was designed as an eight element linear array wrapped around the neck with three circular elements on each side of the neck and two longer rectangular elements on the anterior neck and chester. In phantom and in vivo studies this coil shows higher SNR and lower g factors than clinically available coils throughout the desired FOV.

Aziz Kadjo¹, Ludovic Martin-Durupty¹, Raymond Cespuglio², Danielle Graveron-Demilly¹, and Latifa Fakri-Bouchet^1
1University of Lyon, Lyon1,Laboratoire CREATIS-LRMN, UMR CNRS 5220, INSERM U 630, INSA de Lyon, Villerbanne, France, ²University of Lyon, Lyon1, Laboratoire «Radicaux libres/substrats énergie et physiopatho cérébrale, Lyon cedex 08, France

Considering the need to explore a limited sample volume (microlitre), the feasibility to use a new micro-coil concept is proposed. Simulations of B1 field distribution correlated to MR imaging, demonstrates the potential of micro-coil in terms of sensitivity, (Vactive~2 µl), SNR and limits of detection (LOD). Estimated LOD from MR-observable brain metabolite spectra are compared to those obtained using a commercial surface-coil. A gain factor about 2 is obtained. The micro-coil advantage, in spite of its small sensitive volume, to detect a small concentration is demonstrated. This result opens the way to new spatially resolved explorations on animal model.

Adam Maunder¹, Tyler Charlton¹, B. Gino Fallone^1,2, and Nicola De Zanche^1,2
1Dept. of Oncology, University of Alberta, Edmonton, Alberta, Canada, ²Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada

Complete arrays capture all three components of the RF magnetic field using additional loops placed orthogonally to the standard surface coils. This experimental study at 3T confirms improvements in SNR and parallel imaging performance predicted by theory, and demonstrates an effective method to increase channel density three-fold without decreasing coil size.

Amol Pednekar¹, Claudio Arena², Greg Wilson³, Cecilia Possanzini⁴, Charles Saylor², and Raja Muthupillai^2
1Philips Healthcare, Houston, Texas, United States, ²Diagnostic and Interventional Radiology, St. Luke's Episcopal Hospital, Houston, Texas, United States, ³Philips Healthcare, Cleveland, United States, ⁴Philips Healthcare, Best, Netherlands

The study summarises the experience with a 62 element neurovascular array. (a) It is feasible to obtain a high resolution 3D-ToF images of the entire neuro-vascular tree from the aortic arch to the intra-cranial vessels ( < 8 min), as well as targeted high-resolution carotid vessel wall imaging ( < 7 min) using a 62 element coil array without operator intervention; (b) Automated selection of coil elements using SNR contribution to the region of interest performed just as well as manual selection of dedicated coil elements.

Martin Meyerspeer^1,2, Rolf Gruetter^1,3, and Arthur W Magill^1,4
1LIFMET, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, ²MR Centre of Excellence and ZMPBMT, Medical University of Vienna, Vienna, Austria, ³Radiology, University of Geneva and Lausanne, Switzerland, Switzerland, ⁴Radiology, University of Lausanne, Lausanne, Switzerland

Trapped coil designs allow the operation of lower-frequency coils in the presence of a proton coil. Adding a second capacitor to a trap in the non-proton RF coil allows control over the trap reactance at the low and high frequency (here 13C and 1H) and the frequency of the trap mode. We demonstrate the interdependence of the parameters controlled and show analytical and numerical solutions to fulfill the design constraints. Our experiments show that, using the simulations, it possible to construct an effective second order trap for 13C at 7T.

Assunta Vitacolonna¹, Sandro Romanzetti², Joerg Felder², Nadim Jon Shah^2,3, Antonello Sotgiu⁴, and Marcello Alecci^1
1Scienze della Salute, University of L'Aquila, L'Aquila, Italy, ²Inst. of Neuroscience and Medicine, Research Centre, Jülich, Germany, ³Faculty of Medicine, Department of Neurology, RWTH Aachen University, Aachen, Germany, ⁴ITA srl, L'Aquila, Italy

Sodium MRI/MRS benefits of improved SNR obtainable at high fields (3-12 T). Surface TEM resonators are especially designed for high-field applications. In recent works a novel double-tuned (DT) surface TEM resonator, made by three microstrip elements and suitable for sodium and proton MRI at 4T was described. Here, we report workbench and 4T MRI data showing the optimization of the RF field distribution of the 23Na channel by a proper selection of the relative distance between the external microstrips, while maintaining the 1H field distribution.

Raffi Kalayciyan¹, Friedrich Wetterling¹, Sabine Neudecker², and Lothar R. Schad^1
1Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany, ²Medical Research Center, Heidelberg University, Mannheim, Germany

The quantification of local Tissue Sodium Concentration (TSC) can serve as a diagnostic measure for renal diseases, because TSC is strongly linked to the corticomedullary function regulating the vascular ion concentrations. In this work, for the TSC quantification the required homogeneous B1 is achieved by a dual RF resonator system composed of a newly-developed low noise preamplifier receive-only coil without the need to tune and match, that was used in conjunction with a commercial transmit birdcage volume resonator. The TSC quantification in the rat kidney was illustrated through TSC maps using 3D-UTE sequence.

Mark Jacobus van Uden¹, Yi Sun¹, and Arend Heerschap^1
1Department of Radiology (667), Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands

Within tissue engineering the restore, replacement or regeneration of defective tissues and their function by biological substitutes is monitored. To monitor this process contrast agents that contain fluorine atoms are used. Defects that are inflicted on a rat hind leg are imaged on 1H and 19F. An overlay of these image provides a good insight in the healing process. We present a Helmholtz pair that has a good coverage and good SNR to image rat hind leg. The Helmholtz pair is combined using a Wilkinson lumped element divider/ splitter.

Ivan Emilov Dimitrov^1,2, Craig R Malloy^3,4, and Andrew G Webb^5
1Philips Medical Systems, Cleveland, OH, United States, ²Advanced Imaging Reseach Center (AIRC), UT Southwestern, Dallas, TX, United States, ³Advanced Imaging Research Center (AIRC), UT Southwestern, Dallas, TX, United States, ⁴VA North Texas Health Care System, Dallas, TX, United States, ⁵Radiology, Leiden University Medical Center, Leiden, Netherlands

The metabolic implications of lipid accumulation may depend on the composition of the fat itself. Analytical high-resolution studies of ¹³C have shown the ability of MRS to distinguish a variety of fat components. Here we report on a high-sensitivity ¹³C surface coil with tailored penetration designed to specifically obtain high-resolution human in vivo carbon spectra of subcutaneous fat at 7T. The coil uses a zig-zag pattern with 5 mm distance between the opposing-current segments and shows the desired penetration depth of a few millimeters. In vivo coupled spectra show high sensitivity, and good decoupling is observed in phantoms.

Laura Claire Bell¹, Eric T Peterson¹, Jeremy W Gordon¹, Sean B Fain¹, and Krishna N Kurpad^1
1Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, United States

Development of radio frequency dual-tuned coils is important for spectral shimming and correct functional/anatomical registration. We present a dual-tuned 1H/13C Orthogonal Double Solenoid (ODS) volume coil for pre-clinical applications. This design can be placed coaxially within the bore of horizontal small animal scanner, upholds the 1H SNR at high fields and the sensitivity of 13C, and its versatile design has the potential to image other nuclides of choice. Preliminary results from simultaneous acquisition of a rat in vivo demonstrate feasibility of the coil design.

Wolfgang Driesel¹, Andre Pampel¹, Christian Labadie², Toralf Mildner³, and Harald E. Möller^4
1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Saxony, Germany, ²Max Planck Institute for Human Cognitive and Brain Sciences, ³Max Planck Institute for Human Cognitive and Brain Sciences, Germany, ⁴Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

In this work, the concept of a stacked combination of loop coils and microstrip transmission-line (MTL) elements was adopted to build a helmet-shaped, dual-tuned array coil for human brain 31P spectroscopy and 1H decoupling and imaging at 3 T. The 1H channel is based on a pure MTL design with four spokes. On each spoke, a loop coil was added to permit 31P transmission/reception (Tx/Rx). Initial results from investigations of the performance for 31P MRSI including phantom studies are presented.

Thomas Michael Barbara¹, Manoj Sammi¹, John Grinstead², and William D Rooney^1
1AIRC, Oregon Health and Sciences University, Portland, Oregon, United States, ²Siemens Healthcare, Portland, Oregon

An axially oriented loop resonator is used to obtain ¹H co-registration images for ³¹P spectroscopic imaging at 7T using a 12 leg ³¹P birdcage coil. The 8 cm diameter loop provides extended coverage from crown to brain stem with low coupling to the ³¹P volume coil. This approach provides a useful alternative to the careful subject positioning required with two coils or the construction of a double tuned resonator.

Stefan Alt¹, Marco Müller¹, Armin Michael Nagel¹, Florian Meise¹, Reiner Umathum¹, and Michael Bock^1
1Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany

The native wave propagation mode of a coaxial waveguide (TEM) has no cut-off frequency, which offers the opportunity of broadband operation for mulit-nuclei studies. We acquired proton (¹H) and sodium (²³Na) images at four different Larmor frequencies from 63 to 297MHz using the same coaxial waveguide setup for both spin excitation and signal reception.

Junghwan Kim¹, Chanhong Moon¹, Bumwoo Park¹, Alessandro Furlan¹, Anthony Defranco², Tiejun Zhao³, and Kyongtae Ty Bae^1
1Department of Radiology, University of Pittsburgh, Pittsburgh, PA, United States, ²MR research center, University of Pittsburgh, Pittsburgh, PA, United States, ³MR Research Support, Siemens Healthcare, Pittsburgh, PA, United States

We have developed a multi-transceiver dual-tuned knee coil at 3T which provides high SNR and imaging depth for sodium and co-register of both proton and sodium imaging in a single session. The coil allowed us to acquire in vivo knee cartilage with high SNR in a clinically acceptable time (~30 minutes total session). Further studies on B1-phase shimming are essential to produce a homogenous B1 field and to test the accuracy and reliability of sodium concentration measurement in knee cartilage.

Wolfgang Driesel¹, André Pampel¹, Christian Labadie¹, Toralf Mildner¹, Harald E Moeller¹, and Harald E Moeller^1
1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

Previously, a modular approach has been suggested for designing large arrays. It is based on a stacked combination of loop coils and microstrip transmission-line (MTL) elements, which are intrinsically orthogonal. In this work, this concept was adopted to build a helmet-shaped, dual-tuned array coil for human brain 31P spectroscopy and 1H decoupling and imaging at 3 T. The 1H channel is based on a pure MTL design with four spokes. On each spoke, a loop coil was added to permit 31P transmission/reception (Tx/Rx). Initial results from investigations of the performance for 31P MRSI including phantom studies are presented.

Matthew Finnerty¹, Xiaoyu Yang¹, Tsinghua Zheng¹, Jeremiah Heilman¹, Nicholas Castrilla¹, Joseph Herczak¹, Hiroyuki Fujita^1,2, Graham C Wiggins³, Ryan Brown³, Guillaume Madelin³, Gregory Chang³, Ravinder R Regatte³, Michael Recht³, Siegfried Trattnig⁴, Vladimir Juras⁴, Wolfgang Renz⁵, Franz Schmitt⁵, Bernd Stoeckel⁶, Andreas Potthast⁵, and Karsten Wicklow^5
1Quality Electrodynamics, Mayfield Village, Ohio, United States, ²Departments of Physics and Radiology, Case Western Reserve University, Cleveland, Ohio, United States, ³Department of Radiology, NYU Langone Medical Center, New York, New York, United States, ⁴Department of Radiology, Medical University of Vienna, Vienna, Austria, ⁵Siemens Healthcare, Erlangen, Germany,⁶Siemens Medical Solutions USA, Inc., Malvern, Pennsylvania, United States

The higher SNR found at 7T allows for more diagnostic applications for nuclei other than hydrogen. In particular, sodium imaging has been found to be useful in characterizing cartilage degeneration in the joints, with the focus primarily on the knee. In an effort to design RF coil hardware optimized for these x-nuclei applications, a 12-rung birdcage transmitter and 15-channel receive-only array coil has been developed for sodium imaging of the knee.

Mark Jacobus van Uden¹, Fernando Bonetto^1,2, E.G.W. ter Voert¹, Stephan Orzada³, IJM de Vries², Hanneke van Laarhoven⁴, and Arend Heerschap^1
1Department of Radiology (667), Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands, ²Department of Tumor Immunology, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands, ³Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany, ⁴Department of Medical Oncology, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands

Homogeneous excitation and reception provides a much better base for in vivo absolute quantification of cells and drugs levels with respect to inhomogeneous signal distribution. In this work we present a Helmholtz pair that is capable of generating a homogeneous transmit field at both 1H and 19F at 3T. To obtain signals with high SNR and optimal coverage over the liver and lymph nodes two dedicated multiple element receive coils were developed.