Contact

Sahar Nassirpour

Address: Spemannstr. 41
72076 Tübingen
Room number: 3.A.02
Phone: +49 7071 601 939
Fax: +49 7071 601 702
E-Mail: Sahar.Nassirpour

 

Picture of Nassirpour, Sahar,

Sahar Nassirpour

Position: PhD Student  Unit: Henning Scheffler

- PhD student at Max Planck Institute for Biological Cybernetics

- Ultra High Field Department

- The purpose of my PhD thesis is to develop acquisition sequences, image reconstruction methods and quantification routines to enable whole brain metabolic imaging and quantification in the human brain by magnetic resonance spectroscopy at 9.4T.

Accelerated Multi-slice 1H FID-MRSI in the human brain at 9.4 T


Introduction:

Magnetic resonance spectroscopic imaging (MRSI) is a very powerful technique for mapping of the metabolites over the entire brain volume that can provide sensitive markers of disease or injury and therefore plays an important role both in clinical diagnostics and in biomedical research. Compared to lower field strengths, MRSI at ultra-high fields has the advantage of higher signal to noise ratio as well as increased spectral resolution. This advantage enables the quantification of more metabolites in the brain. However, to be able to benefit from these advantages at ultra-high fields, there are many challenges that should be overcome. Some of these challenges include: shortened T2 and T2* relaxation times, severe chemical shift displacement artifacts, high spatial B1+ field inhomogeneity, long acquisition times, large B0 field inhomogeneity across the entire brain volume and processing of large multi-dimensional datasets in a robust and efficient manner. The purposes of this PhD thesis is to develop acquisition sequences, image reconstruction methods and quantification routines to overcome these challenges and enable whole brain metabolic imaging and quantification in the human brain by magnetic resonance spectroscopy at 9.4T.

 

Preliminary work:

To overcome the rather long scan times of MRSI, previous studies have suggested short repetition times (TR) [1] as well as parallel imaging strategies which accelerate the scan by acquiring only a fraction of the data points in k-space. However, an appropriate unfolding reconstruction algorithm is required. To that end, a target driven SENSE [2] reconstruction algorithm has been introduced [3], which minimizes the effects of voxel bleedings by direct control of the spatial response function.

To demonstrate the feasibility of short TR accelerated multi-slice 1H MRSI in the human brain, an in-vivo experiment was conducted with the above mentioned methods on a healthy volunteer using a 9.4T whole body scanner (Siemens, Erlangen, Germany).  The following image shows representative spectra  on a 3x3x3 voxel grid from this multi-slice spectroscopy exam before and after twofold acceleration indicating high resemblance. These results show that acceleration in combination with a target driven reconstruction algorithm is a promising technique for reducing the rather long scan times of MRSI since it yields similar spectral quality as in the non-accelerated case. However, future work on advanced B0 shimming methods is necessary to fully exploit the advantage of 1H MRSI in the human brain at 9.4T.

 

 

[1] Bogner W, et al, NMR Biomed, 2012; 25:873-882

[2] Pruessmann KP, et al, MRM, 42:952–962 (1999)

[3] Kirchner T, et al, Magnetic Resonance in Medicine 2014; 25185

Education:

06.2014 - Present:

Max Planck Institut für Biologishe Kybernetik, Tübingen

PhD Candidate

High-field Magnetic-Resonance Group

Graduate School of Neural and Behavioural Science

 

09.2009 - 12.2013:

Stanford University, Stanford, California

M.Sc. in Image System Engineering

Electrical Engineering Department

 

09.2004 - 06.2009:

Sharif University of Technology, Tehran, Iran

B.Sc. in Electrical Engineering

Electrical Engineering Department

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Show abstracts

Articles (2):

Chang P, Nassirpour S and Henning A (March-2017) Modeling real shim fields for very high degree (and order) B0 shimming of the human brain at 9.4 T Magnetic Resonance in Medicine Epub ahead.
Nassirpour S, Chang P and Henning A (December-2016) High and ultra-high resolution metabolite mapping of the human brain using 1H FID MRSI at 9.4T NeuroImage Epub ahead. in press

Posters (6):

Chang YC, Nassirpour S, Fillmer A and Henning A (May-10-2016): Correcting Geometric Distortion in B0 Mapping, 24th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2016), Singapore.
Chang YC, Nassirpour S and Henning A (May-10-2016): Very high order B0 Shimming of the human brain at 9.4 T considering Real B0 Shim Fields, 24th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2016), Singapore.
Chang P, Nassirpour S and Henning A (March-2016): Very High‐order B0 Shimming for Single‐Shot EPI at 9.4 T in the Human Brain, ISMRM Workshop on Ultra High Field MRI: Technological Advances & Clinical Applications, Heidelberg, Germany.
Nassirpour S, Kirchner T, Giapitzakis IA and Henning A (June-4-2015): Accelerated Multi-slice 1H FID-MRSI in the human brain at 9.4 T, 23rd Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2015), Toronto, Canada.
Giapitzakis IA, Nassirpour S, Avdievich N, Kreis R and Henning A (June-4-2015): Metabolite cycled single voxel 1H spectroscopy at 9.4T, 23rd Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2015), Toronto, Canada.
Giapitzakis IA, Nassirpour S, Kreis R, Avdievich NI and Henning A (March-19-2015): Metabolite cycled proton magnetic resonance spectroscopy at 9.4T, 10th Annual Meeting of the European Society for Molecular Imaging (EMIM 2015), Tübingen, Germany.

Talks (5):

Nassirpour S (August-16-2016) Abstract Talk: Metabolite Mapping of the Human Brain Using 1H FID MRSI at 9.4T, ISMRM Workshop on MR Spectroscopy: From Current Best Practice to Latest Frontiers, Allensbach-Hegne, Germany.
Nassirpour S (August-15-2016) Abstract Talk: A Comparison of Optimization Algorithms for Localized In-Vivo Shimming, ISMRM Workshop on MR Spectroscopy: From Current Best Practice to Latest Frontiers, Allensbach-Hegne, Germany.
Nassirpour S, Chang YC, Fillmer A and Henning A (May-13-2016) Abstract Talk: A Comparison of Optimization Algorithms for Localized in-vivo B0 Shimming, 24th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2016), Singapore(1142).
Giapitzakis IA, Nassirpour S, Avdievich NI, Kreis R and Henning A (October-2015) Abstract Talk: 1H single voxel spectroscopy at occipital lobe of human brain at 9.4 T, 32nd Annual Scientific Meeting ESMRMB 2015, Edinburgh, UK, Magnetic Resonance Materials in Physics, Biology and Medicine, 28(1 Supplement) S208-S209.
Giapitzakis IA, Nassirpour S and Henning A (October-2015) Abstract Talk: Short duration water suppresion using optimised flip angles (SODA) at ultra high fields, 32nd Annual Scientific Meeting ESMRMB 2015, Edinburgh, UK, Magnetic Resonance Materials in Physics, Biology and Medicine, 28(1 Supplement) S401-S402.

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Last updated: Tuesday, 18.11.2014