7 Tesla Multinuclear MRI: Oxygen imaging

Groupleader : Dr. rer. nat. Sebastian Niesporek

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Dr. rer. nat. Sebastian Niesporek
Medical Physics in Radiology
7T Multinuclear MRI: Oxygen Imaging

Tel.: +49 6221 42 4941
Fax: +49 6221 42 3058
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The aim of this project group is to provide the necessary parts for efficient metabolic imaging. Development, improvement and optimization of post processing techniques, the experimental setup as well as investigation of additional, supporting imaging modalities (e.g. 25Mg-MRI) are one focus. In vivo application and small cohort studies in interdisciplinary cooperation with de Department of Radiology are the second important pillar.

Multinuclear Imaging

In recent years the development and installation of magnet resonance imaging (MRI) scanners with magnetic field strengths B0 of 7T and beyond has let to numerous improvements and developments in proton and non-proton (multinuclear) imaging. Whereas proton imaging generates contrasts that mainly reflect pathological structures data of other nuclei, so called x-nuclei, as for example sodium (23Na), potassium (39K), chloride (35Cl), oxygen (17O), magnesium (25Mg), phosphorus (31P) bear information of metabolic and functional origin. Whereas 23Na, 39K, and 35Cl ion concentrations mirror the cell physiology and can be applied in various body regions (7 Tesla Multinuclear MRI: Sodium Imaging).

There are various technical and methodical challenges in the process of realization of multinuclear MRI and especially 17O MRI. Different nuclei possess, due to their physical properties, different resonance frequencies and require special hardware and scanner components during imaging. Furthermore due to lower gyromagnetic rations and concentrations and nuclear spins >1/2 and the available signal is lower (~10-3-10-5 of the proton signal) and experiences much faster decay (so-called T2/ T2*-relaxation). Therefore special techniques and post-processing algorithms have be developed to efficiently use the reduced signal.

Visualization of the energy metabolism: Oxygen Imaging

Dynamic 17O MRI utilizes the only MR detectable oxygen isotope (17O) to absolutely quantify the functional parameter of the cerebral metabolic rate of oxygen consumption (CMRO2), reflecting the energy metabolism in the human brain. The CMRO2 parameter is an indicator of cell viability. In many diseases such as Parkinson’s or in Alzheimer’s disease or cancer (‘Warburg Effect’) CMRO2 is reduced and might therefore be an important diagnostic parameter. The method, which includes inhalation of 17O2 gas, was first validated in a volunteer study, where we could verify our results and show reproducibility. Measuring various glioma patients demonstrated the capability of dynamic 17O MRI for direct metabolic imaging generating a functional contrast between healthy and malignant tissue. Future work includes investigation of further pathologies and optimization of the current method for a more cost efficient use of 17O2 gas as well as fundamental research in the animal model at the newly acquired 9.4T PET/MRI animal scanner

Example structural 1H and metabolic 17O MRI in a patient (WHO grade IV glioblastoma), Clinical anatomical 1H images with delineated tumor volume without (A) and after contrast media administration with typical tumor ring enhancement and (B). Color-coded map of relative 17O signal change with/ without fusion of 1H MRI data (C, D). Regions of tumor tissue show a clearly reduced metabolic activity measured with information of dynamic 17O MRI demonstrating the metabolic contrast in tumor tissue. Tumor metabolism is shifted to a more anaerobic pathway, consuming less oxygen than healthy tissue (‘Warburg-Effect’). Data acquired at the German Cancer Research Center (DKFZ), Heidelberg.

Publications

Niesporek SC, Umathum R, Lommen JM, Behl NGR, Paech D, Bachert P, Ladd ME, Nagel AM. Reproducibility of CMRO2 determination using dynamic (17) O MRI. Magn Reson Med 2018;79(6):2923-2934.

Niesporek S, Nagel A, Umathum R, Behl NG, Ladd ME, Schlemmer HP, Paech D. Metabolic Rate of Oxygen Consumption in Brain Tumors: A Pilot 17O-MRI Study. In: Proceeding 25th Annual Meeting of the International Society of Magnetic Resonance in Medicine (ISMRM) 2018.

Niesporek SC, Umathum R, Fiedler TM, Bachert P, Ladd ME, Nagel AM. Improved T2* determination in 23Na, 35Cl, and 17O MRI using iterative partial volume correction based on 1H MRI segmentation. Magnetic Resonance Materials in Physics, Biology and Medicine 2017:1-18.

Niesporek SC, Hoffmann SH, Berger MC, Benkhedah N, Kujawa A, Bachert P, Nagel AM. Partial volume correction for in vivo (23)Na-MRI data of the human brain. Neuroimage 2015;112:353-363.

Benkhedah N, Hoffmann SH, Biller A, Nagel AM. Evaluation of adaptive combination of 30-channel head receive coil array data in 23Na MR imaging. Magn Reson Med 2016;75(2):527-536.

Hoffmann SH, Radbruch A, Bock M, Semmler W, Nagel AM. Direct (17)O MRI with partial volume correction: first experiences in a glioblastoma patient. MAGMA 2014;27(6):579-587.

Hoffmann SH, Begovatz P, Nagel AM, Umathum R, Schommer K, Bachert P, Bock M. A measurement setup for direct 17O MRI at 7 T. Magn Reson Med 2011;66(4):1109-1115.

Konstandin S, Nagel AM, Heiler PM, Schad LR. Two-dimensional radial acquisition technique with density adaption in sodium MRI. Magn Reson Med 2011;65(4):1090-1096.

Nagel AM, Laun FB, Weber MA, Matthies C, Semmler W, Schad LR. Sodium MRI using a density-adapted 3D radial acquisition technique. Magn Reson Med 2009;62(6):1565-1573.

Research topics

Multinuclear images from top to bottom): human torso (²³Na), human heart (²³Na) low grade glioma (17O), human head (²³Na, yellow box).

•    Metabolic imaging in the human brain (dynamic 17O MRI)
•    Development, implementation, validation of reconstruction
      and correction methods (iterative reconstruction, partial volume correction)
•    Animal experiments with 17O MRI
•    Hardware development (coils, experimental setup)
•    Pulse sequence and reconstruction techniques

Job Offers

If you are interested to participate as part of your Bachelor’s, Master’s, or Ph.D. thesis, we are more than happy to discuss potential projects with you. Please do not hesitate to contact us.

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