Comparison of three multichannel transmit/receive radiofrequency coil configurations for anatomic and functional cardiac MRI at 7.0T: implications for clinical imaging

Winter, Lukas; Kellman, Peter; Renz, Wolfgang; Gräßl, Andreas; Hezel, Fabian; Thalhammer, Christof; Knobelsdorff‐Brenkenhoff, Florian von; Ткаченко, В. Е.; Schulz‐Menger, Jeanette; Niendorf, Thoralf

doi:10.1007/s00330-012-2487-1

Cited by 68 publications

(62 citation statements)

References 20 publications

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“…This finding is in alignment with a recent in vivo study performed at The results reported for this feasibility study are likely to pave the way for further advances in RF coil technology tailored for assessment of skin sodium content. These efforts will help to further gain sensitivity by reducing loop element size and by including more loop elements as recently demonstrated for transceiver arrays customized for proton MRI at 7.0 T (41)(42)(43)(44)(45)(46), and hence will contribute to further improvements of in-plane resolution. The use of a large slice thickness for transversal slices of skin in the lower leg implies perfect orientation of the calf-skin and agarose standards parallel to the main axis of the MR scanner to reduce partial volume effects of skin Na + signal, Na + free environment and low Na + subcutaneous fat tissue.…”

Section: Discussionmentioning

confidence: 99%

Skin sodium measured with ²³Na MRI at 7.0 T

et al. 2014

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Objective: Skin-sodium storage, as a physiologically important regulatory mechanism for blood pressure, volume regulation, and indeed survival, has recently been rediscovered. This prompted the development of MRI methods to assess sodium storage in humans ( 23 Na-MRI) at 3.0 Tesla. This work examines the feasibility of high in-plane spatial resolution 23 Na MRI in skin at 7.0 T. Methods:A two-channel transceiver RF coil array tailored for skin MRI at 7.0 T (f=78.5MHz) is proposed. Specific absorption rate (SAR) simulations and a thorough assessment of RF power deposition were performed to meet the safety requirements. Human skin was examined in an in vivo feasibility study using 2D gradient echo imaging. Normal male adult volunteers (n=17, mean ± SD = 46 ± 18 years, range: 20-79 years) were investigated.Transverse slices of the calf were imaged with 23 Na MRI using a high in-plane resolution of (0.9 x 0.9) mm 2 . Skin Na + content was determined using external agarose standards covering a physiological-range of Na + concentrations. To assess the intra-subject reproducibility, each volunteer was examined three to five times with each session including a 5 min walk and repositioning/preparation of the subject. Age-dependence of skin Na + content was investigated. Results:The 23 Na RF coil provides improved sensitivity within a range of 1 cm from its surface versus a volume RF coil which facilitates high in-plane spatial resolution imaging of human skin. Intra-subject variability of human skin sodium content in the volunteer population was <10.3%. An age-dependent increase in skin Na + content was observed, r = 0.78). Short abstractThis work demonstrates the feasibility of sub-millimeter in-plane spatial resolution 23 Na MRI in skin at clinically acceptable acquisition times at 7.0 T. Intra-subject variability of human skin sodium content in the volunteer population was <10.3%. An age-dependent increase in skin Na + content was observed (r = 0.78). Assigning sodium stores with 23 Na-MRI techniques could be improved at 7.0 T compared to current 3.0 T technology.-6 -

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Section: Discussionmentioning

confidence: 99%

Skin sodium measured with ²³Na MRI at 7.0 T

et al. 2014

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“…In addition to SNR gains and phase noise reduction at UHF (111)(112)(113), improvements are expected by using local multi-channel receive arrays for MR thermometry which demonstrated major SNR benefits over the use of the traditional RF body coil approach and are clinical routine (B0 ≤ 3.0T) (98,(114)(115)(116).…”

Section: Integrated Systems or Thermal Mrmentioning

confidence: 99%

Magnetic resonance thermometry: Methodology, pitfalls and practical solutions

Winter

Oberacker

Paul

et al. 2015

International Journal of Hyperthermia

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Clinically established thermal therapies like thermo ablative approaches or adjuvant hyperthermia treatment rely on accurate thermal dose information for the evaluation and adaptation of the thermal therapy. Intratumoral temperature measurements have been correlated successfully with clinical endpoints. Magnetic resonance imaging is the most suitable technique for non-invasive thermometry avoiding complications related to invasive temperature measurements. Since the advent of MR thermometry two decades ago, numerous MR thermometry techniques have been developed continuously increasing accuracy and robustness for in vivo applications. While this progress was primarily focused on relative temperature mapping, current and future efforts will likely close the gap towards quantitative temperature readings. These efforts are essential to benchmark thermal therapy efficiency, understand temperature related biophysical and physiological processes and to use these insights to set new landmarks for diagnostic and therapeutic applications. With that in mind, this review summarizes and discusses advances in MR thermometry providing practical considerations, pitfalls and technical obstacles constraining temperature measurement accuracy, spatial and temporal resolution in vivo. Established approaches and current trends in thermal therapy hardware are surveyed with respect to potential benefits for MR thermometry.3

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“…To address this obstacle multi-element transceiver coil arrays have been developed. These developments took advantage of building blocks that include stripline elements (34)(35)(36)(37)(38), dielectric resonant antennae (39), loop elements (40)(41)(42)(43)(44)(45)(46) and electrical dipoles (47)(48)(49)(50)(51)(52)(53).…”

Section: Theorymentioning

confidence: 99%

Electrodynamics and radiofrequency antenna concepts for human magnetic resonance at 23.5 T (1 GHz) and beyond

Winter

Niendorf

2016

Magn Reson Mater Phy

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Materials and MethodsElectromagnetic field simulations (EMF) are performed in phantoms with average tissue simulants for dipole antennae using discrete frequencies (300MHz (7.0T) to 3GHz (70.0T)).To advance to a human setup EMF simulations are conducted in anatomical human voxel models of the human head using a 20-element dipole array operating at 1 GHz. ResultsOur results demonstrate that transmission fields suitable for 1 H MR of the human brain can be achieved at 1GHz. An increase in transmit channel density around the human head helps to enhance B1 + in the center of the brain. The calculated relative increase in specific absorption rate (SAR) at 23.5T vs. 7.0T was below 1.4 (in-phase phase setting) and 2.7 (circular polarized phase setting) for the dipole antennae array. ConclusionThe benefits of multi-channel dipole antennae at higher frequencies render MR at 23.5Tfeasible from an electrodynamic standpoint. This very preliminary finding opens the door on further explorations that might be catalyzed into a 20 Tesla class human MR system.2

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Comparison of three multichannel transmit/receive radiofrequency coil configurations for anatomic and functional cardiac MRI at 7.0T: implications for clinical imaging

Cited by 68 publications

References 20 publications

Skin sodium measured with ²³Na MRI at 7.0 T

Skin sodium measured with ²³Na MRI at 7.0 T

Magnetic resonance thermometry: Methodology, pitfalls and practical solutions

Electrodynamics and radiofrequency antenna concepts for human magnetic resonance at 23.5 T (1 GHz) and beyond

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Comparison of three multichannel transmit/receive radiofrequency coil configurations for anatomic and functional cardiac MRI at 7.0T: implications for clinical imaging

Cited by 68 publications

References 20 publications

Skin sodium measured with 23Na MRI at 7.0 T

Skin sodium measured with 23Na MRI at 7.0 T

Magnetic resonance thermometry: Methodology, pitfalls and practical solutions

Electrodynamics and radiofrequency antenna concepts for human magnetic resonance at 23.5 T (1 GHz) and beyond

Contact Info

Product

Resources

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Skin sodium measured with ²³Na MRI at 7.0 T

Skin sodium measured with ²³Na MRI at 7.0 T