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Kontakt

Shajan Gunamony

Adresse: Spemannstr. 41
72076 Tübingen
Raum Nummer: 3.B.06
Tel.: 07071 601 734
Fax: 07071 601 702
E-Mail: Shajan.Gunamony

 

Bild von Gunamony, Shajan

Shajan Gunamony

Position: Wissenschaftler  Abteilung: Scheffler

In magnetic resonance imaging, radio frequency (RF) coils are used to produce RF magnetic fields in order to excite the nuclei as well as for acquisition of the induced NMR signal. The push towards higher static magnetic field strength in search of higher signal to noise ratio increases the RF (B1) field frequency. Constructive and destructive interferences due to the resultant shorter wavelength in tissue create strong inhomogeneities in the B1+ field produced by conventional coils. Hence specialized RF hardware and B1 management methods are required to obtain high-quality images that take full advantage of the increased static field strength.

            I am involved in the development of RF coils and associated front-end RF hardware like low noise preamplifiers, TR switches, quadrature hybrids etc for the 9.4 T human MRI scanner and 16.4 T small animal scanner.

RF Coils for Human Brain MRI at 9.4T 

Transmit Only Receive Only Coil Arrays

At Larmor frequencies as high as 400 MHz, transmit array coils are essential tools to mitigate B1+ field inhomogeneities caused by the shorter wavelength in tissue. Additional flexibility to influence the B1+ field in the lower brain regions like the cerebellum and the lower temporal lobes can be achieved by unique coil layouts like the dual-row transmit array configuration.

 

In this project, an actively detunable 16-element dual row transmit loop coil was designed which could be combined with our 31-channel receive only helmet for increased sensitivity during reception. Furthermore, since the transmit array has built-in TR switches with preamplifiers, this coil can be easily combined with mulit-nuclei coils for co-localization.

    

 

 

 

Transceiver Arrays

In this project, the complete RF front-end required for human MRI at 9.4 T was designed and evaluated. A 16 channel elliptical transceiver array using microstrip transmission line elements was designed. To separate the transmit and receive functions, TR switches and preamplifiers were designed. The coil can be operated in circularly polarized mode or RF shimming methods can be applied to favourably influence the transmit field.

 

 

RF Coils for MRI at 16.4T

Our lab is equipped with one of the strongest horizontal bore magnets currently available for small animal MRI. RF coils optimized for rat brain imaging, whole body mouse imaging etc were developed for imaging in this scanner.

    

Professional Experience:

1998-2000               Scientist/Engineer at the ISRO Satellite Center, Indian Space Research Organization, Bangalore, India
2001-2007     Senior Engineer in the MR Engineering Group, GE Healthcare, Bangalore, India
Since July 2007 Research Scientist at the Max Planck Institute for Biological Cybernetics, Tuebingen, Germany

Education:

1991 - 1995                   Bachelor of Engineering in Electronics and Communication Engineering, Karunya Institute of Technology, Coimbatore, India
1996 - 1998 Master of Engineering in Communication Systems, Thiagarajar College of Engineering, Madurai, India

Patent:

RF Coil Assembly US patent No. 7605588 / HF-Spulenanordnung (DE102006050989A1)

Präferenzen: 
Referenzen pro Seite: Jahr: Medium:

  
Zeige Zusammenfassung

Artikel (13):

Shajan G Person, Kozlov M , Hoffmann J Person, Turner R , Scheffler K Person und Pohmann R Person (Februar-2014) A 16-channel dual-row transmit array in combination with a 31-element receive array for human brain imaging at 9.4 T Magnetic Resonance in Medicine 71(2) 870–879.
Budde J Person, Shajan G Person, Scheffler K Person und Pohmann R Person (Februar-2014) Ultra-high resolution imaging of the human brain using acquisition-weighted imaging at 9.4 T NeuroImage 86 592–598.
Budde J Person, Shajan G Person, Zaitsev M , Scheffler K Person und Pohmann R Person (Januar-2014) Functional MRI in human subjects with gradient-echo and spin-echo EPI at 9.4 T Magnetic Resonance in Medicine 71(1) 209–218.
Mirkes CC Person, Hoffmann J Person, Shajan G Person, Pohmann R Person und Scheffler K Person (Januar-2014) High-resolution quantitative sodium imaging at 9.4 tesla Magnetic Resonance in Medicine Epub ahead.
Balla DZ Person, Gottschalk S Person, Shajan G Person, Ueberberg S , Schneider S , Hardtke-Wolenski M , Jaeckel E , Hoerr V , Faber C , Scheffler K Person, Pohmann R Person und Engelmann J Person (Dezember-2013) In vivo visualization of single native pancreatic islets in the mouse Contrast Media & Molecular Imaging 8(6) 495-504.
Hoffmann J Person, Shajan G Person, Scheffler K Person und Pohmann R Person (November-2013) Numerical and experimental evaluation of RF shimming in the human brain at 9.4 T using a dual-row transmit array Magnetic Resonance Materials in Physics, Biology and Medicine Epub ahead.
Hoffmann J Person, Shajan G Person, Budde J Person, Scheffler K Person und Pohmann R Person (Mai-2013) Human brain imaging at 9.4 T using a tunable patch antenna for transmission Magnetic Resonance in Medicine 69(5) 1494–1500.
Pohmann R Person, Shajan G Person, Hoffmann J Person, Budde J Person, Hagberg G Person, Bieri O , Bisdas S , Ernemann U , Weigel M , Ehses P Person, Hennig J , Chadzynski G und Scheffler K Person (April-2013) Imaging and Spectroscopy at 9.4 Tesla: First Results on Patients and Volunteers MAGNETOM Flash 2013(2) 58-67.
Shajan G Person, Hoffmann J Person, Balla DZ Person, Deelchand DK , Scheffler K Person und Pohmann R Person (Oktober-2012) Rat brain MRI at 16.4T using a capacitively tunable patch antenna in combination with a receive array NMR in Biomedicine 25(10) 1170–1176.
Pohmann R Person, Shajan G Person und Balla D Person (Dezember-2011) Contrast at high field: Relaxation times, magnetization transfer and phase in the rat brain at 16.4 T Magnetic Resonance in Medicine 66(6) 1572-1581.
Shajan G Person, Hoffmann J Person, Budde J Person, Adriany G , Ugurbil K und Pohmann R Person (August-2011) Design and Evaluation of an RF Front-End for 9.4 T Human MRI Magnetic Resonance in Medicine 66(2) 594–602.
Budde J Person, Shajan G Person, Hoffmann J Person, Ugurbil K und Pohmann R Person (Februar-2011) Human imaging at 9.4 T using T2*-, phase-, and susceptibility-weighted contrast Magnetic Resonance in Medicine 65(2) 544-550.
Hong S-T Person, Balla DZ Person, Shajan G Person, Choi C , Ugurbil K und Pohmann R Person (Januar-2011) Enhanced neurochemical profile of the rat brain using in vivo 1H NMR spectroscopy at 16.4 T Magnetic Resonance in Medicine 65(1) 28-34.
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Beiträge zu Tagungsbänden (1):

Balla DZ Person, Ehses P Person, Pohmann R Person, Budde J Person, Mirkes C Person, Shajan G Person, Bowtell R und Scheffler K Person (Juli-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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Poster (33):

Ehses P Person, Shajan G Person und Scheffler K Person (Mai-15-2014): 3D Radial GRE-EPI with Up to 8-Fold Acceleration for Functional Imaging at 9.4T, Joint Annual Meeting ISMRM-ESMRMB 2014, Milano, Italy.
Chadzynski GL Person, Henning A Person, Ehses P Person, Hoffmann J Person, Shajan G Person und Scheffler K Person (Mai-15-2014): High-Resolution Free Induction Decay Proton MRSI in the Human Brain at 9.4 T, Joint Annual Meeting ISMRM-ESMRMB 2014, Milano, Italy.
Mirkes CC Person, Shajan G Person, Hoffmann J Person, Brenner D , Pohmann R Person und Scheffler K Person (Mai-15-2014): Sodium B1 mapping at 9.4 T, Joint Annual Meeting ISMRM-ESMRMB 2014, Milano, Italy.
Hoffmann J Person, Mirkes C Person, Shajan G Person, Scheffler K Person und Pohmann R Person (Mai-13-2014): 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.
Bause J Person, Ehses P Person, Shajan G Person, Scheffler K Person und Pohmann R Person (Mai-12-2014): Functional ASL at 9.4 T: a Comparison Between Balanced SSFP and GRE-EPI Readout, Joint Annual Meeting ISMRM-ESMRMB 2014, Milano, Italy.
Goense J Person, Beyerlein M Person, Hoffmann J Person, Shajan G Person, Steudel T Person, Scheffler K Person, Logothetis NK Person und Merkle H Person (Mai-12-2014): Novel RF-Coil Assembly to Simultaneously Investigate fMRI and Electrophysiology in Non-Human Primates in a Large Bore Vertical Magnet, Joint Annual Meeting ISMRM-ESMRMB 2014, Milano, Italy.
Balla DZ Person, Ehses P Person, Pohmann R Person, Budde J Person, Mirkes C Person, Shajan G Person, Bowtell R und Scheffler K Person (Juli-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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Hagberg GE Person, Martirosian P , Bause J Person, Shajan G Person, Klose U und Scheffler K Person (April-25-2013): Time-Of-Flight Angiography in Humans at 9.4T, 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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Bakhtiary M Person, Shajan G Person, Hoffmann J Person, Scheffler K Person und Pohmann R Person (April-2013): 31P-spectroscopy on humans at 9.4 T in combination with a patch antenna for proton imaging: Initial results, 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 Person, Hoffmann J Person, Shajan G Person, Pohmann R Person und Scheffler K Person (April-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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Mirkes C Person, Hoffmann J Person, Shajan G Person, Pohmann R Person und Scheffler K Person (April-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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Kozlov M , Shajan G Person und Turner R (April-2013): Effects of Tuning Condition, Head Size and Position on the SAR of a 9.4T Dual Row Array, 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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Chadzynski G Person, Bisdas S , Hagberg G Person, Pohmann R Person, Shajan G Person, Kolb R , Klose U und Scheffler K Person (April-2013): First Proton CSI of a Human Brain Tumor at 9.4T, 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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Chadzynski G Person, Pohmann R Person, Shajan G Person, Kolb R , Klose U und Scheffler K Person (April-2013): Gradient Induced Sideband Artifacts in non Water-Suppressed Proton CSI of the Human Brain 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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Budde J Person, Shajan G Person, Scheffler K Person und Pohmann R Person (April-2013): Ultra-High-Resolution Imaging of the Human Brain at 9.4 T Using k-Space Weighted Acquisition, 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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Budde J Person, Shajan G Person, Scheffler K Person und Pohmann R Person (März-2013): k-Space Weighted Acquisition for Ultra-High-Resolution Imaging of the Human Brain at 9.4 T, ISMRM Workshop Ultra High Field MRI: What is in Full Bloom & What is Sprouting?, Noordwijk aan Zee, Netherlands.
Bause J Person, Shajan G Person, Hoffmann J Person, Scheffler K Person und Pohmann R Person (Mai-7-2012): Design and SAR Estimation of a Segmented Loop for Dual Coil CASL at 9.4 T, 20th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2012), Melbourne, Australia.
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Ehses P Person, Budde J Person, Shajan G Person und Scheffler K Person (Mai-2012): Distortion-free high-resolution fMRI at 9.4 T, 20th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2012), Melbourne, Australia.
Budde J Person, Shajan G Person, Zaitsev M , Scheffler K Person und Pohmann R Person (Mai-2012): Human functional imaging at 9.4 T: Spin echo and gradient echo EPI, 20th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2012), Melbourne, Australia.
Shajan G Person, Hoffmann J Person und Pohmann R Person (Mai-2011): A 15-channel receive array and 16 channel detunable transmit coil for human brain imaging at 9.4 T, 19th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2011), Montréal, Canada.
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Budde J Person, Mühlbauer F Person, Shajan G Person, Zaitsev M und Pohmann R Person (Mai-2011): Human fMRI at 9.4 T: Preliminary Results, 19th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2011), Montréal, Canada.
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Shajan G Person, Hoffmann J Person, Balla DZ Person und Pohmann R Person (Mai-2010): A 700MHz Receive Array using Patch Antenna for Spin Excitation, ISMRM-ESMRMB Joint Annual Meeting 2010, Stockholm, Sweden.
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Hoffmann J Person, Shajan G Person und Pohmann R Person (Mai-2010): Capacitively Tunable Patch Antenna for Human Head Imaging at 9.4 Tesla, ISMRM-ESMRMB Joint Annual Meeting 2010, Stockholm, Sweden.
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Balla DZ Person, Wiesner HM Person, Shajan G Person und Pohmann R Person (Mai-2010): Functional MRI in the rat at 9.4 T and 16.4 T, ISMRM-ESMRMB Joint Annual Meeting 2010, Stockholm, Sweden.
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Budde J Person, Shajan G Person, Mühlbauer F Person, Hoffmann J Person, Ugurbil K und Pohmann R Person (Mai-2010): Human T2* and Phase Imaging at 9.4 T, ISMRM-ESMRMB Joint Annual Meeting 2010, Stockholm, Sweden.
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Hong S-T Person, Balla DZ Person, Shajan G Person, Choi C , Ugurbil K und Pohmann R Person (Mai-2010): Localized in Vivo 1H NMR Spectroscopy of the Rat Brain at 16.4T, ISMRM-ESMRMB Joint Annual Meeting 2010, Stockholm, Sweden.
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Hong S-T Person, Balla DZ Person, Shajan G Person, Choi C und Pohmann R Person (Mai-2010): Regional Variations of Metabolite Concentrations in the Rat Brain Assessed with in vivo 1H MR Spectroscopy at 16.4T, ISMRM-ESMRMB Joint Annual Meeting 2010, Stockholm, Sweden.
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Hoffmann J Person, Budde J Person, Shajan G Person und Pohmann R Person (Mai-2010): Slice-Selective B1 Phase Shimming at 9.4 Tesla, ISMRM-ESMRMB Joint Annual Meeting 2010, Stockholm, Sweden.
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Balla DZ Person, Wiesner HM Person, Shajan G Person und Pohmann R Person (April-2009): Functional MRI in the rat brain with single-shot gradient echo EPI at 16.4 T, 17th Annual Meeting of the International Society for Magnetic Resonance in Medicine (ISMRM 2009), Honolulu, HI, USA.
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Hong S-T Person, Balla DZ Person, Shajan G Person, Ugurbil K und Pohmann R Person (April-2009): Highly Accurate Quantification of Proton MR Spectroscopy in Rat Brain in Vivo at 16.4 T, 17th Annual Meeting of the International Society for Magnetic Resonance in Medicine (ISMRM 2009), Honolulu, HI, USA.
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Balla DZ Person, Wiesner HM Person, Shajan G Person, Faber C und Pohmann R Person (April-2009): TurboCRAZED BOLD imaging detects specific activation in the rat brain after somatosensory stimulation at 16.4 Tesla, 17th Annual Meeting of the International Society for Magnetic Resonance in Medicine (ISMRM 2009), Honolulu, HI, USA.
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Shajan G Person, Balla DZ Person, Hoffmann J Person und Pohmann R Person (Oktober-2008): A Microstrip Resonator for Animal MRI at 16.4 T, ESMRMB 2008 Congress: 25th Annual Meeting, Valencia, Spain, Magnetic Resonance Materials in Physics, Biology and Medicine, 21(Supplement 1) 449-450.
Balla DZ Person, Hong S-T Person, Shajan G Person, Pohmann R Person und Ugurbil K (Mai-2008): Single Voxel MR Spectroscopy with Echo Times Below 2 ms at 16.4 T in the Rat Brain: First in vivo Results, 16th Scientific Meeting and Exhibition of the International Society of Magnetic Resonance in Medicine (ISMRM 2008), Toronto, Canada.
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Vorträge (14):

Shajan G Person, Mirkes C Person, Hoffmann J Person, Scheffler K Person und Pohmann R Person (Mai-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).
Mirkes C Person, Hoffmann J Person, Shajan G Person, Pohmann R Person und Scheffler K Person (Oktober-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.
Hoffmann J Person, Shajan G Person, Scheffler K Person und Pohmann R Person (Oktober-4-2013) Abstract Talk: Combination of Multimode Traveling-Wave Excitation and TIAMO for Human Brain Imaging at 9.4 T, 30th Annual Scientific Meeting ESMRMB 2013, Toulouse, France, Magnetic Resonance Materials in Physics, Biology and Medicine, 26(Supplement 1) 192.
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Last updated: Freitag, 17.01.2014