Contact

Ali Aghaeifar

Address: Spemannstr. 41
72076 Tübingen
Room number: 3.B.10
Phone: +49 7071 601 941
Fax: +49 7071 601 702
E-Mail: Ali.Aghaeifar

 

Picture of Aghaeifar, Ali

Ali Aghaeifar

Position: PhD Student  Unit: Scheffler

Human brain shimming at 9.4T with a multi-coil setup


 

The homogeneity of the main static magnetic field (B0) is a crucial prerequisite for MR imaging due to the manifold image artifacts that can arise from field perturbations. B0 inhomogeneity becomes more pronounced with increasing field strength and can lead to severe image distortions [1]. Usually, the scanner’s inbuilt shim system, which creates spherical harmonic (SH) field terms, is used for global static shimming. Recently, smaller local coils were proposed in the literature to achieve a higher shim performance [2]. We have made a multi-coil setup to achieve a superior homogeneity of the B0 field.

A multi-coil shim setup was constructed consisting of 16 circular coils, which were arranged in two rows. Each coil had 25 wire turns and a diameter of 100 mm. The coils were mounted on a fiber-glass cylinder having a diameter of 370 mm and a length of 310 mm. A custom-built amplifier was used to drive the 16 coils individually. Performance of the multi-coil setup was evaluated in terms of global and slice-wise dynamic shimming.

 

 

 

 

[1] S. Sengupta et al., “Dynamic B0 shimming at 7 T,” Magn. Reson. Imaging, vol. 29, no. 4, pp. 483–496, 2011.

[2] C. Juchem, T. W. Nixon, S. McIntyre, D. L. Rothman, and R. A. De Graaf, “Magnetic field modeling with a set of individual localized coils,” J. Magn. Reson., vol. 204, no. 2, pp. 281–289, 2010.


 

 

Advanced motion correction for high-resolution EPI imaging


 

Magnetic resonance imaging (MRI) is one of the most widely used non-invasive research tools for functional imaging. However, Image quality is highly sensitive to the subject motion, and undesired motions lead to artifacts in final image. EPI is one of the most favorite pulse sequences used in functional imaging since it almost owns the best scan time and enables to images rapid physiological functions in human brain. Despite lots of benefits, EPI suffer from high degree of sensitivity to B0 field inhomogeneity. Subject motion is one cause to motivate higher local field inhomogeneity.

To provide a high quality imaging capability, in one hand, accurate control of the radio-frequency (RF) pules and gradient fields in MRI are necessary. On the other hand, facing higher fields for higher image resolution, shimming is a substantial concept in imaging to achieve homogeneous slices.

The aim of this project is to address motion artifacts in EPI imaging through prospective motion correction. We will use position feedback signal from NMR field probes, installed on the subject, to discern subject position. Having new updated position, in a real-time framework the sequence will change the slice orientation by updating the gradients. Thereafter, to overcome field inhomogeneity resulted from subject motion, shimming coefficients will be reconfigured before the next excitation.

Education:


 

Since 11.2014

PhD student at Max Planck for Biological Cybernetics & Graduate School of Neuroscience (Neural and Behavioral Science), University of Tuebingen.

09.2010 - 09.2012

M.Sc. in Electrical Engineering, Iran University of Science & Technology, Tehran, Iran

09.2006 - 08.2010

B.Sc. in Biomedical Engineering, AmirKabir University of Technology (Tehran Polytechnic), Tehran, Iran

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Posters (6):

Aghaeifar A, Loktyushin A, Eschelbach M and Scheffler K (October-20-2017): Improving performance of linear field generation with multi-coil setup by optimizing coils position, 34th Annual Scientific Meeting of the European Society for Magnetic Resonance in Medicine and Biology (ESMRMB 2017), Barcelona, Spain, Magnetic Resonance Materials in Physics, Biology and Medicine, 30(Supplement 1) S259.
Eschelbach M, Aghaeifar A, Engel E-M and Scheffler K (October-19-2017): Prospective Head Motion Correction Using Multiple Tracking Modalities, 34th Annual Scientific Meeting of the European Society for Magnetic Resonance in Medicine and Biology (ESMRMB 2017), Barcelona, Spain, Magnetic Resonance Materials in Physics, Biology and Medicine, 30(Supplement 1) S68-S69.
Mirkes C, Shajan G, Aghaeifar A, Zivkovic I, Buckenmaier K and Scheffler K (April-26-2017): Dual-layered multi-channel B0 and RF coil setup for an improved shimming performance at 9.4 Tesla, 25th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2017), Honolulu, HI, USA.
Aghaeifar A, Zivkovic I, Mirkes C, Steffen T and Scheffler K (April-25-2017): Global and dynamic shimming with the scanner’s inbuilt shim system and a custom-made multi-coil setup at 9.4 T, 25th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2017), Honolulu, HI, USA.
Eschelbach M, Aghaeifar A, Bause J, Handwerker J, Anders J, Thielscher A and Scheffler K (April-24-2017): A Comparison of Prospective Motion Correction with 19F NMR Field Probes and an Optical Camera, 25th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2017), Honolulu, HI, USA.
Aghaeifar A, Moghaddam AN and Scheffler K (April-24-2017): Motion simulation and correction validation using MR tagging, 25th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2017), Honolulu, HI, USA.

Talks (8):

Bause J, Aghaeifar A, In M-H, Engel E-M, Ehses P, Eschelbach M, Scheffler K and Pohmann R (October-19-2017) Abstract Talk: Distortion and prospective motion corrected zoomed functional imaging of the human brain at 9.4 Tesla, 34th Annual Scientific Meeting of the European Society for Magnetic Resonance in Medicine and Biology (ESMRMB 2017), Barcelona, Spain, Magnetic Resonance Materials in Physics, Biology and Medicine, 30(Supplement 1) S125-S126.
Aghaeifar A, Zivkovic I, Steffen T, Mirkes C and Scheffler K (October-19-2017) Abstract Talk: Flexible gradient driver system for a multi-coil shim setup: design considerations and implementation, 34th Annual Scientific Meeting of the European Society for Magnetic Resonance in Medicine and Biology (ESMRMB 2017), Barcelona, Spain, Magnetic Resonance Materials in Physics, Biology and Medicine, 30(Supplement 1) S50-S51.
Bause J, Aghaeifar A, Hagberg G, Engel E-M, Avdievitch N, Scheffler K and Pohmann R (September-11-2017) Abstract Talk: 350 μm Isotropic Whole-Brain MP2RAGE without Averaging, ISMRM Workshop on Motion Correction in MRI & MRS (MoCor 2017), Cape Town, South Africa.
Aghaeifar A, Eschelbach M and Scheffler K (September-10-2017) Abstract Talk: Multi-Modality Prospective Motion Correction of Human Head, ISMRM Workshop on Motion Correction in MRI & MRS (MoCor 2017), Cape Town, South Africa.
Aghaeifar A, Eschelbach M, Bause J, Thielscher A and Scheffler K (April-24-2017) Abstract Talk: AMoCo, a software package for prospective motion correction, 25th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2017), Honolulu, HI, USA 219.
Aghaeifar A, Eschelbach M and Scheffler K (September-2016) Abstract Talk: Real time communications over UDP protocol, European IDEA Users Group Meeting 2016, Maastricht, The Netherlands.
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).
Kühne M, Ergin MA, Klare S, Eschelbach M, Aghaeifar A, Thielscher A and Peer A (May-2015) Abstract Talk: Towards an MR-compatible Haptic Interface with Seven Actuated Degrees of Freedom, IEEE International Conference on Robotics and Automation (ICRA 2015), Seattle, WA, USA.

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Last updated: Monday, 22.05.2017