Contact

Jonas Bause

Address: Spemannstr. 41
72076 Tübingen
Room number: 3.B.03
Phone: +49 7071 601 922
Fax: +49 7071 601 702
E-Mail: jonas.bause

 

Picture of Bause, Jonas

Jonas Bause

Position: PhD Student  Unit: Scheffler

Perfusion Measurement with Arterial Spin Labeling at 9.4 T


Introduction

Local and global variations in brain perfusion can occur in a number of diseases like stroke, vascular malfunctions and inflammation processes. The main physiological process which leads to changes in cerebral blood flow (CBF) is neural activity. The most common method to map neural activity evoked by a specific task is blood oxygen level dependent (BOLD) fMRI. The interpretation of BOLD signals, however, is complicated by their dependence on several additional parameters like blood volume and oxygen consumption. Furthermore BOLD fMRI has a low spatial specificity and some methods are strongly influenced by draining vessels.

Variations in CBF can be measured independently with several invasive methods like 15O positron emission tomography (PET) and dynamic susceptibility contrast (DSC) MRI. However, the only non-invasive and rapidly repeatable method to map variations in cerebral blood flow caused by neural activity is arterial spin labeling (ASL) MRI. ASL-MRI has a high temporal and spatial resolution and offers the possibility for quantitative measurements. Furthermore, arterial spin labeling can be combined with BOLD fMRI in calibrated experiments to measure changes in the metabolic rate of oxygen. The major drawback of this method is that the change in signal intensity due to perfusion is only in the range of few percent. Therefore, the SNR in ASL-MRI is poor and signal averaging and/or a lower spatial resolution has to be used to achieve reasonable SNR in the resulting CBF maps.

Ultra high-field MRI systems provide the capability for higher spatial and temporal resolution due the linear relationship between SNR and the strength of the magnetic field. In addition, perfusion measurements with ASL-MRI may benefit from longer longitudinal relaxation times at higher field strengths. The limiting factors of ASL at 9.4T are the high power demands of the arterial spin labeling pulses and the resulting high SAR values as well as inhomogeneous transmit fields and shorter transverse relaxation times.

 

 

Implementation of Pulsed ASL at 9.4 T

Quantitative ASL - comparison between 9.4  T and 3 T

The pulsed arterial spin labeling technique FAIR has a comparatively low power deposition and is virtually unaffected by magnetization transfer effects. For this reason, a FAIR sequence was implemented using an optimized adiabatic inversion pulse and an in-plane presaturation method with reduced sensitivity to transmit field inhomogeneities. Quantitative measurements were performed at 3 T and 9.4 T to determine the actual performance of ASL at ultra-high field. Corrected for the different voxel size, the 9.4 T showed a 2.3 higher SNR compared to 3 T.
Acquisition parameters:  Preparation TR 4 s, TE 17/18 ms (9.4 T/ 3T), 400-2800 ms (stepwidth 400 ms), voxel size 2x2x3 mm³ (9.4 T), 3x3x3 mm³ (3 T).

Perfusion weighted images obtained at 9.4 T and 3 T. Quantitative perfusion maps of the same slices.

 

Functional ASL

Functional arterial spin labeling signal can be contaminated with BOLD related signal changes which makes its interpretation difficult. This is especially the case at ultra-high field when a gradient echo based EPI readout with cartesian k-space sampling is used due to the shorter T2* relaxation times. As an alternative with reduced T2* and thus BOLD weighting, a balanced SSFP (bSSFP) readout was implemented and evaluated in a functional experiment where the subjects were asked to perform a simple finger tapping task. A clear increase in perfusion signal during the task can be seen for both readouts.
Acquisiton parameters: Preparation TR 5 s, TI 1700 ms, voxel size 2x2x2.5 mm³, 60 tag-control pairs.

Obtained activation maps of the ASL sequences and a reference BOLD measurement co-registered on an anatomical GRE.

 

Implementation of Dual-Coil Continuous ASL at 9.4 T

Continuous labeling techniques typically permit a higher signal to noise ratio than pulsed labeling techniques. However, a flow driven adiabatic inversion can only be achieved using either SAR intensive approaches where a high number of RF pulses are applied in a thin slab located in the inferior region of the head (so called pseudo continuous ASL) or by using a dedicated labeling coil in the neck of the subject (also called dual-coil continuous ASL). However, beside the additional labeling coil the latter approach requires an external RF amplifier which is capable of transmitting long RF pulses (duration >1 s) and an additional safety circuit to avoid risks for the subject due to RF heating. The picture shows one of the labeling coils for 9.4 T.

since Nov. 2010 PhD Student at the Magnetic Resonance Center of the Max-Planck Institute for Biological Cybernetics, Tübingen, Germany.
PhD project: Magnetic Resonance Perfusion Measurement with Arterial Spin Labeling at Ultra-High Field.

 

2005-2010 Medical engineering studies with an emphasis on medical equipment technology at the University of Applied Sciences, Ulm, Germany.
Degree: Diplom-Ingenieur (Fachhochschule)

 

Diploma Thesis (October 2009 – March 2010) at the Max-Planck Institute for Biological Cybernetics, Tübingen, Germany.
Topic: Non-invasive Temperature Measurement at Ultra-high Fields.

 

Practical training semester (March 2008 – August 2008) at the Department of Radiation Sciences, University Umeå, Sweden.
Project: Development and evaluation of a SPM based Matlab tool to compensate patient movements in dynamic contrast enhanced MRI (DCE-MRI) time series.

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Articles (6):

Loureiro JR, Hagberg GE, Ethofer T, Erb M, Bause J, Ehses P, Scheffler K and Himmelbach M (January-2017) Depth-dependence of visual signals in the human superior colliculus at 9.4 T Human Brain Mapping 38(1) 574–587.
Hagberg GE, Bause J, Ethofer T, Ehses P, Dresler T, Herbert C, Pohmann R, Shajan G, Fallgatter A, Pavlova MA and Scheffler K (January-2017) Whole brain MP2RAGE-based mapping of the longitudinal relaxation time at 9.4T NeuroImage 144(Part A) 203–216.
Chadzynski GL, Bause J, Shajan G, Pohmann R, Scheffler K and Ehses P (November-2016) Fast and efficient free induction decay MR spectroscopic imaging of the human brain at 9.4 Tesla Magnetic Resonance in Medicine Epub ahead.
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.
Ehses P, Bause J, Shajan G and Scheffler K (December-2015) Efficient generation of T2*-weighted contrast by interslice echo-shifting for human functional and anatomical imaging at 9.4 Tesla Magnetic Resonance in Medicine 74(6) 1698–1704.

Conference papers (1):

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.

Posters (12):

Stelzer J, Ehses P, Bause J, Scheffler K and Lohmann G (November-16-2016): Resolving large-scale networks in ultra-high field fMRI (9.4T) of the human brain, 46th Annual Meeting of the Society for Neuroscience (Neuroscience 2016), San Diego, CA, USA.
Chadzynski GL, Bause J, Shajan G, Pohmann R, Scheffler K and Ehses P (May-11-2016): Fast and efficient free induction decay MRSI at 9.4 T: assessment of neuronal activation-related changes in the human brain biochemistry, 24th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2016), Singapore.
Lacosse E, Bause J, Lohmann G, Scheffler K, Schaal S and Sternad D (April-2016): Neural Control of Discrete and Rhythmic Movement, 26th Annual Meeting of the Society for the Neural Control of Movement (NCM 2016), Montego Bay, Jamaica.
Chadzynski GL, Ehses P, Bause J, Shajan G, Pohmann R and Scheffler K (January-15-2016): A novel approach to assess an extended biochemical profile of the human brain by the means of fast and efficient in-vivo proton Magnetic Resonance Spectroscopic Imaging at 9.4 Tesla, Forschungskolloquium 2016 der Medizinischen Fakultät, Tübingen, Germany.
Martin P, Hagberg G, Loureiro J, Bause J, Erb M, Lerche H, Scheffler K and Focke N (January-15-2016): Strukturelle Hochfeld-MRT-Bildgebung bei Epilepsie, Forschungskolloquium 2016 der Medizinischen Fakultät, Tübingen, 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.
Bause J, In M-H, Ehses P, Shajan G, Speck O, Pohmann R and Scheffler K (June-3-2015): Distortion-Corrected High Resolution Zoomed fMRI at 9.4 T, 23rd Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2015), Toronto, Canada.
Chadzynski G, Hagberg GE, Bause J, Shajan G, Bisdas S, Pohmann R, Engelmann J and Scheffler K (March-20-2015): Assessment of human brain tumors with proton magnetic resonance spectroscopic imaging at 9.4 Tesla, 10th Annual Meeting of the European Society for Molecular Imaging (EMIM 2015), Tübingen, Germany.
Chadzynski G, Bause J, Hagberg GE, Shajan G, Pohmann R, Engelmann J and Scheffler K (March-19-2015): Free induction decay proton magnetic resonance spectroscopic imaging in the healthy human brain at 9.4 Tesla: initial results, 10th Annual Meeting of the European Society for Molecular Imaging (EMIM 2015), Tübingen, Germany.
Bause J, Ehses P, Shajan G, Scheffler K and Pohmann R (May-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.
Hagberg GE, Martirosian P, Bause J, Shajan G, Klose U and Scheffler K (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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Bause J, Shajan G, Hoffmann J, Scheffler K and Pohmann R (May-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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Talks (12):

Bause J (April-23-2017) Invited Lecture: Construction of Rx Arrays, 25th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2017), Honolulu, HI, USA.
Martin P, Hagberg G, Loureiro J, Bause J, Lerche H, Focke N and Scheffler K (October-1-2016) Abstract Talk: Can 9.4 T MRI improve lesion visualization in epilepsy patients?, 33rd Annual Scientific Meeting of the European Society for Magnetic Resonance in Medicine and Biology (ESMRMB 2016), Wien, Austria, Magnetic Resonance Materials in Physics, Biology and Medicine, 29(Supplement 1) S347-S348.
Ehses P, Bause J and Scheffler K (September-30-2016) Abstract Talk: Optimizing inversion-recovery bSSFP for T1 quantification at ultra high-field, 33rd Annual Scientific Meeting of the European Society for Magnetic Resonance in Medicine and Biology (ESMRMB 2016), Wien, Austria, Magnetic Resonance Materials in Physics, Biology and Medicine, 29(Supplement 1) S197.
Hagberg GE, Bause J, Ethofer T, Ehses P, Dresler T, Shajan G, Pohmann R, Herbert C, Fallgatter A, Laske C, Pavlova M and Scheffler K (May-9-2016) Abstract Talk: Consistent detection of age-dependent variations of the longitudinal relaxation time in cortical brain regions investigated by MP2RAGE at 9.4T: influence of correcting for a non-uniform transmit field, 24th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2016), Singapore(0059).
Shajan G, Bause J, Pohmann R and Scheffler K (October-2015) Abstract Talk: Choice of RF coils at 9.4T: SNR and B1+ of transceiver and transmit-only receive-only arrays, 32nd Annual Scientific Meeting ESMRMB 2015, Edinburgh, UK, Magnetic Resonance Materials in Physics, Biology and Medicine, 28(1 Supplement) S58-S59.
Chadzynski GL, Scheffler K, Bause J, Shajan G, Pohmann R and Ehses P (October-2015) Abstract Talk: Fast and efficient free induction decay proton MRSI in the 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) S298-S299.
Bause J, Scheffler K and Pohmann R (October-2015) Abstract Talk: Simulation of Flow-Driven Adiabatic Inversion in Dual Coil Continuous ASL at 9.4 T, 32nd Annual Scientific Meeting ESMRMB 2015, Edinburgh, UK, Magnetic Resonance Materials in Physics, Biology and Medicine, 28(1 Supplement) S367-S368.
Hagberg GE, Bause J, Ethofer T, Dresler T, Herbert C, Pohmann R, Shajan G, Fallgatter A and Scheffler K (October-2015) Abstract Talk: T1 relaxometry and tissue segmentation of the human brain at 9.4T and 3T using MP2RAGE, 32nd Annual Scientific Meeting ESMRMB 2015, Edinburgh, UK, Magnetic Resonance Materials in Physics, Biology and Medicine, 28(1 Supplement) S234-S235.
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.
Chadzynski GK, Hagberg G, Bause J, Shajan G, Bisdas S, Pohmann R and Scheffler K (June-5-2015) Abstract Talk: In-vivo proton MR spectroscopic imaging of the human brain gliomas at 9.4 Tesla: evaluation of metabolite coordinates, 23rd Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2015), Toronto, Canada(0763).
Molaei-Vaneghi F, Bause J, Ehses P, Scheffler K and Bartels A (June-1-2015) Abstract Talk: Encoding Self-Motion and External Motion during Pursuit Eye Movement, A Study at 9.4T, 23rd Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2015), Toronto, Canada(0139).
Bause J, Shajan G, Scheffler K and Pohmann R (October-4-2013) Abstract Talk: High Resolution Arterial Spin Labeling in the Human Brain at 9.4 T: Initial Results using FAIR, 30th Annual Scientific Meeting ESMRMB 2013, Toulouse, France, Magnetic Resonance Materials in Physics, Biology and Medicine, 26(Supplement 1) 257.
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Last updated: Tuesday, 18.11.2014