ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • Journal cover
    Springer
    Online: 1.1993 –
    Publisher: Springer
    Print ISSN: 0968-5243
    Electronic ISSN: 1352-8661
    Topics: Medicine , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • Publication Date: 2012-04-17
    Description: Object   Staff operating in the environment of magnetic resonance imaging (MRI) scanners are exposed daily to static magnetic fields (MFs). To protect workers several guidelines are present in literature reporting exposure limits values expressed in terms of magnetic flux density or induced current density. We present here a novel tool for estimating the induced current density due to worker movement in the MR environment. Materials and methods   A Matlab script was created to estimate the induced current density J due to operator movements along a chosen walking path. Results   The induced current density associated with any worker’s movements during MR procedures is dependent on the walking speed and on the spatial gradient fields associated with a specific path. Some examples of possible worker paths were considered here for a 3 T MR scanner and a maximum value of 160 cm/s walking speed. Conclusion   This tool permits one to find exposure level for specific worker walking path and speed; it can be used as assessment tool in any MRI centre and for workers safety education. It is valid for any kind of commercial scanner because it requires only the knowledge of the MR scanner room map with isogauss lines. Content Type Journal Article Category Research Article Pages 323-330 DOI 10.1007/s10334-011-0279-2 Authors Valentina Hartwig, Institute of Clinical Physiology, National Council of Research, via G. Moruzzi 1, 56124 Pisa, Italy Nicola Vanello, Institute of Clinical Physiology, National Council of Research, via G. Moruzzi 1, 56124 Pisa, Italy Giulio Giovannetti, Institute of Clinical Physiology, National Council of Research, via G. Moruzzi 1, 56124 Pisa, Italy Massimo Lombardi, Fondazione G. Monasterio CNR-Regione Toscana, Pisa, Italy Luigi Landini, Department of Information Engineering, University of Pisa, via G. Caruso 16, 56126 Pisa, Italy Maria Filomena Santarelli, Institute of Clinical Physiology, National Council of Research, via G. Moruzzi 1, 56124 Pisa, Italy Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243 Journal Volume Volume 24 Journal Issue Volume 24, Number 6
    Print ISSN: 0968-5243
    Electronic ISSN: 1352-8661
    Topics: Medicine , Physics
    Published by Springer
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • Publication Date: 2012-04-17
    Description: Object   Two approaches of reconstructing undersampled partial k -space data, acquired with multiple coils are compared: homodyne detection combined with SENSE (HM_SENSE) and analytic image reconstruction combined with SENSE (AI_SENSE). The latter overcomes limitations of HM_ SENSE by considering aliased images as analytic thus avoiding the need for phase correction required for HM_SENSE. Materials and methods   In vivo imaging experiments were carried out in male Lewis rats using both gradient echo and spin echo sequences. Accelerated images obtained by using the various reconstruction algorithms were compared to fully sampled reference images both qualitatively and quantitatively. Results   For the various sampling patterns evaluated, both HM_SENSE and AI_SENSE were found to yield robust image reconstruction with small deviations from the reference image. Even for high acceleration factors AI_SENSE still provided useful results and was found superior compared to HM_SENSE. Conclusion   Combination of partial k -space sampling and parallel image acquisition allows for further acceleration of data acquisition as compared to each method alone. Image reconstruction from undersampled data sets using the AI_SENSE algorithm was found to considerably reduce reconstruction errors and artifacts observed for HM_SENSE reconstruction caused by errors in phase estimation. Content Type Journal Article Category Research Article Pages 305-313 DOI 10.1007/s10334-011-0274-7 Authors Josiane Yankam Njiwa, Institute for Biomedical Engineering, University and ETH Zurich, AIC-ETH, HIT E22, Wolfgang Pauli-Strasse 27, 8093 Zurich, Switzerland Christof Baltes, Institute for Biomedical Engineering, University and ETH Zurich, AIC-ETH, HIT E22, Wolfgang Pauli-Strasse 27, 8093 Zurich, Switzerland Markus Rudin, Institute for Biomedical Engineering, University and ETH Zurich, AIC-ETH, HIT E22, Wolfgang Pauli-Strasse 27, 8093 Zurich, Switzerland Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243 Journal Volume Volume 24 Journal Issue Volume 24, Number 5
    Print ISSN: 0968-5243
    Electronic ISSN: 1352-8661
    Topics: Medicine , Physics
    Published by Springer
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • Publication Date: 2012-04-17
    Description: Object   To design and evaluate a fully shielded, λ/4 stripline resonator as a receive-only surface coil for preclinical MRI at 4.7 T. Materials and methods   A 20 mm diameter stripline surface coil was fabricated from double-sided Duroid 5880 PCB material and was directly coupled to the input of a MOSFET preamplifier, without requiring a matching network. The new coil was compared with a conventional 20 mm, wire loop, receive-only surface coil in imaging experiments with a separate transmit-only saddle coil. Results   The stripline surface coil exhibits a loaded Q -factor of 132 at 200 MHz, compared to 138 for a conventional wire loop coil and its resonant frequency drops by 0.2 MHz under loading, rather than 0.5 MHz for the wire loop. The stripline coil displays a more symmetrical B 1 map compared to the wire loop, but the SNR falls off more rapidly with depth so it is 30% poorer 8 mm from the coil plane. It should be possible, however, to reduce this difference by using a thicker dielectric in future versions of the stripline coil. Conclusion   Compared to a conventional surface coil, the stripline coil is easy to manufacture, requires shorter set-up times and shows reduced dielectric interaction with conductive samples. Content Type Journal Article Category Research Article Pages 331-337 DOI 10.1007/s10334-011-0273-8 Authors Ioannis Lavdas, Comprehensive Cancer Imaging Centre (CCIC), Imperial College MRC Cyclotron Building, Hammersmith Hospital, DuCane Road, London, W12 0NN UK Hugh C. Seton, BioMedical Physics, School of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD UK Charles R. Harrington, School of Medicine and Dentistry, University of Aberdeen and TauRx Therapeutics Ltd., Foresterhill, Aberdeen, AB25 2ZD UK Claude M. Wischik, School of Medicine and Dentistry, University of Aberdeen and TauRx Therapeutics Ltd., Foresterhill, Aberdeen, AB25 2ZD UK Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243 Journal Volume Volume 24 Journal Issue Volume 24, Number 6
    Print ISSN: 0968-5243
    Electronic ISSN: 1352-8661
    Topics: Medicine , Physics
    Published by Springer
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • Publication Date: 2012-04-17
    Description: Object   To develop an ultrafast MRI-based temperature monitoring method for application during rapid ultrasound exposures in moving organs. Materials and methods   A slice selective 90° − 180° pair of RF pulses was used to solicit an echo from a column, which was then sampled with a train of gradient echoes. In a gel phantom, phase changes of each echo were compared to standard gradient-echo thermometry, and temperature monitoring was tested during focused ultrasound sonications. Signal-to-noise ratio (SNR) performance was evaluated in vivo in a rabbit brain, and feasibility was tested in a human heart. Results   The correlation between each echo in the acquisition and MRI-based temperature measurements was good ( R  = 0.98 ± 0.03). A temperature sampling rate of 19 Hz was achieved at 3T in the gel phantom. It was possible to acquire the water frequency in the beating heart muscle with 5-Hz sampling rate during a breath hold. Conclusion   Ultrafast thermometry via phase or frequency monitoring along single columns was demonstrated. With a temporal resolution around 50 ms, it may be possible to monitor focal heating produced by short ultrasound pulses. Content Type Journal Article Category Research Article Pages 5-14 DOI 10.1007/s10334-011-0272-9 Authors Chang-Sheng Mei, Department of Physics, Boston College, Chestnut Hill, MA, USA Robert V. Mulkern, Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA Koichi Oshio, Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA Nan-kuei Chen, Brain Imaging and Analysis Center, Duke University Medical Center, Durham, NC, USA Bruno Madore, Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA Lawrence P. Panych, Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA Kullervo Hynynen, Department of Imaging Research, Sunnybrook Research Institute, Toronto, Canada Nathan J. McDannold, Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243 Journal Volume Volume 25 Journal Issue Volume 25, Number 1
    Print ISSN: 0968-5243
    Electronic ISSN: 1352-8661
    Topics: Medicine , Physics
    Published by Springer
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • Publication Date: 2012-04-17
    Description: Object   The EU directive on safety requirements (2004/40/EC) limits the exposure to time varying magnetic fields to d B /d t = 200 mT/s. This action value is not clearly defined as it considers only the temporal change of the magnitude of ® B   . Thus, only the translational motion in the magnet’s fringe field is considered and rotations are neglected. Materials and methods   A magnetic field probe was constructed to simultaneously record the magnetic flux density ® B   ( x , y , z ) with a 3-axis Hall sensor and the induced voltage due to movements with a set of three orthogonal coils. Voltages were converted into time-varying magnetic flux d Φ ( x , y , z )/d t serving as an exposition parameter for both translations and rotations. To separate the two types of motion, d B /d t was additionally calculated on the basis of the Hall sensor’s data. The calibrated probe was attached to the forehead of 8 healthcare workers and 17 MR physicists, and ® B   and d Φ /d t were recorded during standard operating procedures at three different MR systems up to 7 T. Results   The maximum percentage of the translational motion referring the data including both translations and rotations amounts to 32%. During volunteer measurements, maximum exposure values of d Φ /dt = 21 mWb/s, d B /d t = 1.40 T/s and ê ê ® B   ê ê = 2.75 Twere found. Conclusion   The findings in this work indicate that both translations and rotations in the vicinity of an MR system should be taken into account, and that a single regulatory action level might not be sufficient. Content Type Journal Article Category Research Article Pages 315-322 DOI 10.1007/s10334-011-0270-y Authors Jens Groebner, Department of Medical Physics in Radiology (E020), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany Reiner Umathum, Department of Medical Physics in Radiology (E020), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany Michael Bock, Department of Medical Physics in Radiology (E020), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany Axel J. Krafft, Department of Medical Physics in Radiology (E020), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany Wolfhard Semmler, Department of Medical Physics in Radiology (E020), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany Jaane Rauschenberg, Department of Medical Physics in Radiology (E020), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243 Journal Volume Volume 24 Journal Issue Volume 24, Number 6
    Print ISSN: 0968-5243
    Electronic ISSN: 1352-8661
    Topics: Medicine , Physics
    Published by Springer
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • Publication Date: 2012-04-17
    Description: ESMRMB 2011, 28th Annual Scientific Meeting, Leipzig, Germany, 6-8 October: EPOS TM Posters / Paper Posters / Clinical Review Posters / Software Exhibits Content Type Journal Article Pages 271-543 DOI 10.1007/s10334-011-0268-5 Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243 Journal Volume Volume 24 Journal Issue Volume 24, Supplement 1
    Print ISSN: 0968-5243
    Electronic ISSN: 1352-8661
    Topics: Medicine , Physics
    Published by Springer
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • Publication Date: 2012-04-17
    Description: ESMRMB 2011, 28th Annual Scientific Meeting, Leipzig, Germany, 6-8 October: Abstracts, Saturday Content Type Journal Article Pages 183-270 DOI 10.1007/s10334-011-0267-6 Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243 Journal Volume Volume 24 Journal Issue Volume 24, Supplement 1
    Print ISSN: 0968-5243
    Electronic ISSN: 1352-8661
    Topics: Medicine , Physics
    Published by Springer
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • Publication Date: 2012-04-17
    Description: ESMRMB 2011, 28th Annual Scientific Meeting, Leipzig, Germany, 6-8 October: Abstracts, Friday Content Type Journal Article Pages 98-182 DOI 10.1007/s10334-011-0266-7 Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243 Journal Volume Volume 24 Journal Issue Volume 24, Supplement 1
    Print ISSN: 0968-5243
    Electronic ISSN: 1352-8661
    Topics: Medicine , Physics
    Published by Springer
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • Publication Date: 2012-04-17
    Description: ESMRMB 2011, 28 th Annual Scientific Meeting, Leipzig, Germany, 6-8 October: Abstracts, Thursday Content Type Journal Article Pages 1-97 DOI 10.1007/s10334-011-0265-8 Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243 Journal Volume Volume 24 Journal Issue Volume 24, Supplement 1
    Print ISSN: 0968-5243
    Electronic ISSN: 1352-8661
    Topics: Medicine , Physics
    Published by Springer
    Location Call Number Expected Availability
    BibTip Others were also interested in ...