Contact

Dr. Christian Mirkes

Address: Spemannstr. 41
72076 Tübingen
Room number: 3.B.06
Phone: +49 7071 601 727
Fax: +49 7071 601 702
E-Mail: Christian.Mirkes

 

Picture of Mirkes, Christian, Dr.

Christian Mirkes

Position: Postdoctoral Fellow  Unit: Alumni Scheffler

Sodium (23Na) Imaging at 9.4 Tesla

Overview

Sodium nucleusAlthough hydrogen is the most commonly imaged nucleus in MRI due to its high concentration in biological tissues in the form of water and fat, any other nucleus having a net nuclear spin, e.g. 23Na, 17O, 19F, etc., can be used for imaging and potentially gaining additional information. Even though sodium is the second most abundant nucleus in the human body, the signal produced by it is considerably lower than the one obtained from hydrogen. This is due, on the one hand, to the underlying physics characterising the relaxation of the excited sodium nucleus and, on the other hand, to the 1000 fold lower in vivo concentration.

 

Sodium imaging benefits greatly from the advent of MR scanners with ultra-high magnetic field strengths (>4T). The concomitant increase in sensitivity permits the acquisition of sodium images exhibiting a higher spatial resolution and signal-to-noise ratio (SNR), while maintaining a clinically acceptable scan time. As sodium ions play an important role in cellular homeostasis and cell viability, 23Na MRI can serve as a means for the assessment of cell integrity. Furthermore, degenerative changes, e.g. in articular cartilage, might be assessed in the future by the aid of sodium imaging.

 

Imaging sequences

 

Stack-of-spirals k-space trajectory enabling an ultra-short echo time.The relaxation of the excited sodium nucleus is characterized by a fast (bi-) exponential decay, leading to a large decrease in signal intensity within only a few milliseconds. As standard imaging protocols used for proton imaging are not well suited to cope with this problem, specialized imaging modalities have to be implemented and optimized for the use at ultra-high field strength. In this project, ultra-short echo time (UTE) sequences, such as a stack-of-spirals, were implemented to acquire sodium images at 9.4 T.

 

The use of non-Cartesian imaging sequences enables a more efficient acquisition of the sodium signal. However, the reconstruction of the acquired data becomes more challenging because the data samples are in most cases not anymore evenly spaced in k-space. As a matter of fact the image cannot be reconstructed straightaway by a standard Fourier transformation. Instead, reconstruction algorithms such as gridding must be used to first interpolate the acquired data to a Cartesian grid.

 

Steady-state imaging

SNR comparisonIn most cases sodium images are acquired with long repetition times in order to minimize relaxation weighting. Nevertheless, fast imaging sequences can also be used for sodium imaging and achieve a higher SNR in a shorter time as demonstrated by the images shown on the right-hand side. An SNR comparison was performed for three spiral imaging sequences which used either RF spoiling, gradient spoiling (FISP ─ fast imaging with steady-state precession) or balanced gradients (bSSFP ─ balanced steady-state free precession). The sequence parameters of the used stack of spirals were chosen as follows: nominal resolution 1.5x1.5x4.0 mm3, partitions 52, spiral interleaves per partition 130, TR 10 ms, readout time 3 ms (RF spoiled acquisition and FISP) and 5 ms (bSSFP), acquisition time (TA) 10 min. The duration of the hard excitation pulse was set to 2 ms in order to achieve sufficient flip angle while adhering to the prescribed SAR limits. The bSSFP images exhibit excellent image quality and only a few banding artefacts can be seen. The relative SNR measured in a large region of interest (ROI) in a central slice was: 42 (spoiled acquisition), 44 (FISP), and 56 (bSSFP), respectively.

 

 

Tissue sodium concentration maps

TSC map

Tissue sodium concentration (TSC) maps can be obtained based on UTE images if adequate reference standards are available for calibration. The figure on the left-hand side shows TSC maps acquired at 9.4 T in a healthy volunteer. The nominal resolution of these images is 1x1x5 mm3 and the measurement time was 30 min. Six reference standards were placed below the subject's head in order to relate the measured signal intensity to the sodium concentration. An average sodium concentration of 36±2 and 31±1 mmol/L of wet tissue were found for gray and white matter, respectively.

 

 

 

 

 

 

 

 

 

 

 

 


Education

2015-2016 Scientist at the Max-Planck-Institute for Biological Cybernetics
2011-2016 PhD student at the University of Tübingen, guest scientist at the High-Field Magnetic Resonance Center, MPI for Biological Cybernetics
2005-2011 Diploma in Physics at RWTH Aachen University, Aachen, Germany
2008-2009 Erasmus Exchange Program at Imperial College London, London, United Kingdom

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Articles (11):

Cakić N, Savić T, Stricker-Shaver J, Truffault V, Platas-Iglesias C, Mirkes C, Pohmann R, Scheffler K and Angelovski G (July-2016) Paramagnetic Lanthanide Chelates for Multicontrast MRI Chemical Communications 52(59) 9224-9227.
Mirkes C, Shajan G, Chadzynski G, Buckenmaier K, Bender B and Scheffler K (June-2016) 31P CSI of the human brain in healthy subjects and tumor patients at 9.4 T with a three-layered multi-nuclear coil: initial results Magnetic Resonance Materials in Physics, Biology and Medicine 29(3) 579-589.
Tse DH, Wiggins CJ, Ivanov D, Brenner D, Hoffmann J, Mirkes C, Shajan G, Scheffler K, Uludağ K and Poser BA (June-2016) Volumetric imaging with homogenised excitation and static field at 9.4 T Magnetic Resonance Materials in Physics, Biology and Medicine 29(3) 333–345.
Bause J, Ehses P, Mirkes C, Shajan G, Scheffler K and Pohmann R (March-2016) Quantitative and functional pulsed arterial spin labeling in the human brain at 9.4 t Magnetic Resonance in Medicine 75(3) 1054–1063.
Mirkes C, Shajan G, Bause J, Buckenmaier K, Hoffmann J and Scheffler K (March-2016) Triple-quantum-filtered sodium imaging at 9.4 Tesla Magnetic Resonance in Medicine 75(3) 1278–1289.
Shajan G, Mirkes C, Buckenmaier K, Hoffmann J, Pohmann R and Scheffler K (February-2016) Three-layered radio frequency coil arrangement for sodium MRI of the human brain at 9.4 Tesla Magnetic Resonance in Medicine 75(2) 906–916.
Hoffmann J, Mirkes C, Shajan G, Scheffler K and Pohmann R (January-2016) Combination of a multimode antenna and TIAMO for traveling-wave imaging at 9.4 Tesla Magnetic Resonance in Medicine 75(1) 452–462.
Mirkes CC, Hoffmann J, Shajan G, Pohmann R and Scheffler K (January-2015) High-resolution quantitative sodium imaging at 9.4 tesla Magnetic Resonance in Medicine 73(1) 342–351.
Heule R, Bär P, Mirkes C, Scheffler K, Trattnig S and Bieri O (September-2014) Triple-echo steady-state T2 relaxometry of the human brain at high to ultra-high fields NMR in Biomedicine 27(9) 1037–1045.
Romanzetti S, Mirkes CC, Fiege D, Celik A, Felder J and Shah NJ (August-2014) Mapping tissue sodium concentration in the human brain: A comparison of MR sequences at 9.4 Tesla NeuroImage 96 44–53.
Fiege DP, Romanzetti S, Mirkes CC, Brenner D and Shah NJ (June-2013) Simultaneous single-quantum and triple-quantum-filtered MRI of 23Na (SISTINA) Magnetic Resonance in Medicine 69(6) 1691-1696.

Conference papers (2):

Mirkes C, Shajan G, Hoffmann J, Bause J, Buckenmaier K and Scheffler K (November-2015) Natrium MRT bei 9,4 Tesla, 18. Jahrestagung der Deutschen Sektion der ISMRM e.V. (DS ISMRM 2015), 23-27.
Balla DZ, Ehses P, Pohmann R, Budde J, Mirkes C, Shajan G, Bowtell R and Scheffler K (July-2013) Functional QSM at 9.4T with single echo gradient-echo and EPI acquisition, 2nd International Workshop on MRI Phase Contrast & Quantitative Susceptibility Mapping (QSM 2013), 1-4.
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Posters (14):

Chmelik M, Bencikova D, Mirkes C, Rodgers CT, Shajan G, Scheffler K, Trattnig S and Bogner W (May-11-2016): 31P MRS Signal-to-Noise Ratio in Human Brain at 3, 7, and 9.4 Tesla Using Dual Tuned Head RF Coils, 24th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2016), Singapore.
Zivkovic I, Mirkes C and Scheffler K (March-2016): B0 shimming at 9.4T: 12 channel shim array with combined loop and star coil geometry, ISMRM Workshop on Ultra High Field MRI: Technological Advances & Clinical Applications, Heidelberg, Germany.
Mirkes C, Shajan G, Bause J, Buckenmaier K, Hoffmann J and Scheffler K (June-4-2015): Triple-quantum-filtered sodium imaging at 9.4 Tesla, 23rd Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2015), Toronto, Canada.
Scheffler K, Lohmann G, Mirkes C, Shajan G and Ehses P (June-3-2015): bOVOC: 200 Hz balanced One-Voxel-One-Coil MREG at 9.4T, 23rd Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2015), Toronto, Canada.
Shajan G, Mirkes C, Pohmann R and Scheffler K (June-1-2015): Phosphorus 3D CSI at 9.4 T using a 27-channel Receiver array, 23rd Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2015), Toronto, Canada.
Hoffmann J, Shajan G, Mirkes C, Shao T, Henning A, Pohmann R and Scheffler K (June-1-2015): Towards routine application of dynamic parallel transmission for whole-brain imaging at 9.4 Tesla, 23rd Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2015), Toronto, Canada.
Mirkes CC, Shajan G, Hoffmann J, Brenner D, Pohmann R and Scheffler K (May-15-2014): Sodium B1 mapping at 9.4 T, Joint Annual Meeting ISMRM-ESMRMB 2014, Milano, Italy.
Balla DZ, Ehses P, Pohmann R, Budde J, Mirkes C, Shajan G, Bowtell R and Scheffler K (July-2013): Functional QSM at 9.4T with single echo gradient-echo and EPI acquisition, 2nd International Workshop on MRI Phase Contrast & Quantitative Susceptibility Mapping (QSM 2013), Ithaca, NY, USA.
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Mirkes C, Hoffmann J, Shajan G, Pohmann R and Scheffler K (April-25-2013): Combination of a sodium birdcage coil with a tunable patch antenna for B0 shimming and anatomical localization at 9.4 T, 21st Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2013), Salt Lake City, UT, USA.
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Mirkes C, Hoffmann J, Shajan G, Pohmann R and Scheffler K (April-23-2013): Amide Proton Chemical Exchange Saturation Transfer at 9.4 T with Optimized RF Transmit Field Through B1 Shimming, 21st Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2013), Salt Lake City, UT, USA.
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Abbas Z, Fiege DP, Neuner I, Mirkes CC, Gras V, Romanzetti S and Shah NJ (May-10-2012): Quantitative parametric mapping and tissue sodium concentration at 3T/4T, 20th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2012), Melbourne, Australia.
Romanzetti S, Fiege D, Felder J, Celik A, Mirkes C and Shah NJ (May-10-2012): Ultra-High-Field Sodium Imaging of the Human Brain at 9.4 Tesla, 20th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2012), Melbourne, Australia.
Romanzetti S, Mirkes CC, Fiege D, Celik AA, Felder J and Shah NJ (May-12-2011): A comparison of imaging sequences for sodium MR imaging on a 9.4T whole body machine, 19th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2011), Montréal, Canada.
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Fiege DP, Mirkes CC, Oros-Peusquens A-M, Romanzetti S and Shah NJ (May-11-2011): High-Resolution Sodium Imaging of the Human Brain at 4T, 19th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2011), Montréal, Canada.
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Theses (1):

Mirkes C: Sodium Magnetic Resonance Imaging at 9.4 Tesla, Eberhard-Karls-Universität Tübingen, (2015). PhD thesis

Talks (10):

Zivkovic I, Mirkes C and Scheffler K (May-13-2016) Abstract Talk: B0 shimming at 9.4T using a multicoil approach: coil design with genetic algorithm, 24th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2016), Singapore(1152).
Aghaeifar A, Loktyushin A, Mirkes C, Thielscher A and Scheffler K (May-12-2016) Abstract Talk: Fast B0 first order inhomogeneity estimation using radial acquisition, 24th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2016), Singapore(0932).
Zivkovic I, Mirkes C, Shajan G and Scheffler K (October-2015) Abstract Talk: B0 shimming at 9.4T with multicoil approach: numerical investigation of different coil geometries, 32nd Annual Scientific Meeting ESMRMB 2015, Edinburgh, UK, Magnetic Resonance Materials in Physics, Biology and Medicine, 28(1 Supplement) S391.
Pohmann R, Bause J, Mirkes C, Eschelbach M, Engel E-M and Scheffler K (October-2015) Abstract Talk: Ultrahigh resolution anatomical brain imaging at 9.4 T using prospective motion correction, 32nd Annual Scientific Meeting ESMRMB 2015, Edinburgh, UK, Magnetic Resonance Materials in Physics, Biology and Medicine, 28(1 Supplement) S155.
Mirkes C, Shajan G and Scheffler K (June-1-2015) Abstract Talk: Fast Sodium Imaging at 9.4 Tesla, 23rd Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2015), Toronto, Canada(0064).
Shajan G, Mirkes C, Hoffmann J, Scheffler K and Pohmann R (May-14-2014) Abstract Talk: A Three-Layered Coil Arrangement for Sodium Imaging of the Human Brain at 9.4T, Joint Annual Meeting ISMRM-ESMRMB 2014, Milano, Italy(0620).
Hoffmann J, Mirkes C, Shajan G, Scheffler K and Pohmann R (May-13-2014) Abstract Talk: A 3-Port Traveling-Wave Antenna in Combination with TIAMO for the Acquisition of Void-Free Brain Images at 9.4 Tesla, Joint Annual Meeting ISMRM-ESMRMB 2014, Milano, Italy(0399).
Heule R, Bär P, Mirkes C, Scheffler K, Trattnig S and Bieri O (May-13-2014) Abstract Talk: Fast B1-insensitive T2 relaxometry of the human brain at high to ultra-high fields, Joint Annual Meeting ISMRM-ESMRMB 2014, Milano, Italy(0335).
Mirkes C, Hoffmann J, Shajan G, Pohmann R and Scheffler K (October-5-2013) Abstract Talk: Quantitative Sodium Imaging at 9.4 T, 30th Annual Scientific Meeting ESMRMB 2013, Toulouse, France, Magnetic Resonance Materials in Physics, Biology and Medicine, 26(Supplement 1) 370.
Mirkes CC, Shajan G, Hoffmann J and Scheffler K (October-2012) Abstract Talk: Amide Proton Chemical Exchange Saturation Transfer at 9.4T, 3rd International Workshop on Chemical Exchange Saturation Transfer Imaging (OctoberCEST 2012), Annapolis, MD, USA.
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Last updated: Tuesday, 18.11.2014