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• Schumacher, J., Ahlborg, M., Aderhold, E., Stagge, P., Buzug, T. M. and Gräser, M.: Comparison of Reconstruction Methods for Measured FFL Data, 2022, DOI: 10.18416/IJMPI.2022.2203061.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{https://doi.org/10.18416/ijmpi.2022.2203061, author = {Schumacher, Jonas and Ahlborg, Mandy and Aderhold, Eric and Stagge, Pascal and Buzug, Thorsten M. and Gräser, Matthias}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {buzugthorsten}, number = {1 Suppl 1}, publisher = {International Journal on Magnetic Particle Imaging}, title = {Comparison of Reconstruction Methods for Measured FFL Data}, volume = 8, year = 2022 }

• Ehrhardt, J., Ahlborg, M., Uzunova, H., Buzug, T. M. and Handels, H.: Temporal Polyrigid Registration for Patch-based MPI Reconstruction of Moving Objects, International Journal on Magnetic Particle Imaging, 5(1), 1908001, 2019, DOI: 10.18416/ijmpi.2019.1908001.
  • [ BibTeX ]
  • [ URL ]
  @article{ehrhardt2019temporal, author = {Ehrhardt, Jan and Ahlborg, Mandy and Uzunova, Hristina and Buzug, Thorsten M. and Handels, Heinz}, journal = {International Journal on Magnetic Particle Imaging}, keywords = {buzugthorsten}, number = 1, pages = 1908001, title = {Temporal Polyrigid Registration for Patch-based MPI Reconstruction of Moving Objects}, volume = 5, year = 2019 }

• Erb, W., Weinmann, A., Ahlborg, M., Brandt, C., Bringout, G., Buzug, T. M., Frikel, J., Kaethner, C., Knopp, T., März, T., Möddel, M., Storath, M. and Weber, A.: Mathematical analysis of the 1D model and reconstruction schemes for magnetic particle imaging, Inverse Problems, 34(5), 055012, 2018, DOI: 10.1088/1361-6420/aab8d1.
  • [ BibTeX ]
  @article{Erb_2018, author = {Erb, W and Weinmann, A and Ahlborg, M and Brandt, C and Bringout, G and Buzug, T M and Frikel, J and Kaethner, C and Knopp, T and März, T and Möddel, M and Storath, M and Weber, A}, journal = {Inverse Problems}, keywords = {buzugthorsten}, number = 5, pages = {055012}, title = {Mathematical analysis of the 1D model and reconstruction schemes for magnetic particle imaging}, volume = 34, year = 2018 }
• Ahlborg, M., Kaethner, C., Szwargulski, P., Knopp, T. and Buzug, T. M.: Abstract: Patches in Magnetic Particle Imaging, 2018.
  • [ BibTeX ]
  @inproceedings{ahlborg2018abstract, author = {Ahlborg, Mandy and Kaethner, Christian and Szwargulski, Patryk and Knopp, Tobias and Buzug, Thorsten M.}, booktitle = {Bildverarbeitung für die Medizin}, keywords = {buzugthorsten}, title = {Abstract: Patches in Magnetic Particle Imaging}, year = 2018 }
• Ehrhardt, J., Ahlborg, M., Uzunova, H., Buzug, T. M. and Handels, H.: Temporal Polyrigid Registration for Patch-based MPI Reconstruction of Moving Objects, 55–56, 2018.
  • [ BibTeX ]
  @inproceedings{ehrhardt2018temporal, author = {Ehrhardt, Jan and Ahlborg, Mandy and Uzunova, Hristina and Buzug, Thorsten M. and Handels, Heinz}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {buzugthorsten}, pages = {55-56}, title = {Temporal Polyrigid Registration for Patch-based MPI Reconstruction of Moving Objects}, year = 2018 }
• Ahlborg, M., Kaethner, C., Szwargulski, P., Knopp, T. and Buzug, T. M.: Reusing System Matrices of Patches in Magnetic Particle Imaging via Mirroring, 51–52, 2018.
  • [ BibTeX ]
  @inproceedings{ahlborg2018reusing, author = {Ahlborg, Mandy and Kaethner, Christian and Szwargulski, Patryk and Knopp, Tobias and Buzug, Thorsten M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {AhlborgMandy}, pages = {51-52}, title = {Reusing System Matrices of Patches in Magnetic Particle Imaging via Mirroring}, year = 2018 }

• von Gladiss, A., Graeser, M., Szwargulski, P., Knopp, T. and Buzug, T. M.: Hybrid System Calibration for Multidimensional Magnetic Particle Imaging, Physics in Medicine and Biology, 62(9), 3392–3406, 2017, DOI: 10.1088/1361-6560/aa5340.
  • [ BibTeX ]
  • [ URL ]
  @article{vongladiss2017hybrid, author = {von Gladiss, Anselm and Graeser, Matthias and Szwargulski, Patryk and Knopp, Tobias and Buzug, Thorsten M.}, journal = {Physics in Medicine and Biology}, keywords = {imt}, number = 9, pages = {3392-3406}, title = {Hybrid System Calibration for Multidimensional Magnetic Particle Imaging}, volume = 62, year = 2017 }
• von Gladiss, A., Graeser, M. and Buzug, T. M.: Applying Compressed Sensing on Hybrid System Matrices in Magnetic Particle Imaging, 81, 2017.
  • [ BibTeX ]
  @inproceedings{vongladiss2017applying, author = {von Gladiss, Anselm and Graeser, Matthias and Buzug, Thorsten M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {imt}, pages = 81, title = {Applying Compressed Sensing on Hybrid System Matrices in Magnetic Particle Imaging}, year = 2017 }

• Knopp, T., Kaethner, C., Ahlborg, M. and Buzug, T. M.: X-Space and Chebyshev Reconstruction in Magnetic Particle Imaging, 75, 2016.
  • [ BibTeX ]
  @inproceedings{knopp2016xspace, author = {Knopp, Tobias and Kaethner, Christian and Ahlborg, Mandy and Buzug, Thorsten M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {AhlborgMandy}, pages = 75, publisher = {Infinite Science Publishing}, title = {X-Space and Chebyshev Reconstruction in Magnetic Particle Imaging}, year = 2016 }
• Ahlborg, M.: Bildgebungskonzepte für Magnetic Particle Imaging Bildgebungskonzepte und Rekonstruktionsansätze für große Bildgebungsvolumen bei Magnetic Particle Imaging, Infinite Science Publishing, Lübeck, 2016, ISBN: 9783945954157 3945954150.
  • [ BibTeX ]
  • [ URL ]
  @book{ahlborg2016bildgebungskonzepte, address = {Lübeck}, author = {Ahlborg, Mandy}, keywords = {imt}, publisher = {Infinite Science Publishing}, title = {Bildgebungskonzepte für Magnetic Particle Imaging Bildgebungskonzepte und Rekonstruktionsansätze für große Bildgebungsvolumen bei Magnetic Particle Imaging}, year = 2016 }
• Kaethner, C., Ahlborg, M., Erb, W. and Buzug, T. M.: Lissajous Node Points for a Sytem Matrix based MPI Image Reconstruction Approach, 99, 2016.
  • [ BibTeX ]
  @inproceedings{kaethner2016lissajous, author = {Kaethner, Christian and Ahlborg, Mandy and Erb, Wolfgang and Buzug, Thorsten M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {AhlborgMandy}, pages = 99, title = {Lissajous Node Points for a Sytem Matrix based MPI Image Reconstruction Approach}, year = 2016 }
• Mrongowius, J., Kaethner, C. and Buzug, T. M.: Studies on the Optimization of Efficient Selection and Focus Field Coil Configurations, 30, 2016.
  • [ BibTeX ]
  @inproceedings{mrongowius2016studies, author = {Mrongowius, Julia and Kaethner, Christian and Buzug, Thorsten M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {IMT}, pages = 30, title = {Studies on the Optimization of Efficient Selection and Focus Field Coil Configurations}, year = 2016 }
• Mrongowius, J., Frikel, J. and Kaethner, C.: Tikhonov regularization scheme for image reconstruction in the presence of model errors, 233–236, 2016.
  • [ BibTeX ]
  @inproceedings{mrongowius2016tikhonov, author = {Mrongowius, Julia and Frikel, Jürgen and Kaethner, Christian}, booktitle = {Student Conference Medical Engineering Science}, keywords = {IMT}, pages = {233-236}, title = {Tikhonov regularization scheme for image reconstruction in the presence of model errors}, volume = 5, year = 2016 }
• Medimagh, H. and Buzug, T. M.: Predicting 2D MPI imaging performance using a conventionally acquired or a hybrid 2D system function, 2016.
  • [ BibTeX ]
  @inproceedings{medimagh2016predicting, author = {Medimagh, Hanne and Buzug, Thorsten M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {MedimaghHanne}, title = {Predicting 2D MPI imaging performance using a conventionally acquired or a hybrid 2D system function}, year = 2016 }
• Haensch, A., Kaethner, C., Cordes, A. and Buzug, T. M.: Towards the Characterization of Distortion Artifacts in Elongated Trajectory MPI, 114, 2016.
  • [ BibTeX ]
  @inproceedings{haensch2016towards, author = {Haensch, Annika and Kaethner, Christian and Cordes, Aileen and Buzug, Thorsten M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {IMT}, pages = 114, title = {Towards the Characterization of Distortion Artifacts in Elongated Trajectory MPI}, year = 2016 }
• Ahlborg, M., Kaethner, C., Knopp, T., Szwargulski, P. and Buzug, T. M.: The Influence of Trajectory and System Matrix Overlap on Image Reconstruction Results in Magnetic Particle Imaging, 175, 2016.
  • [ BibTeX ]
  @inproceedings{ahlborg2016influence, author = {Ahlborg, Mandy and Kaethner, Christian and Knopp, Tobias and Szwargulski, Patryk and Buzug, Thorsten M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {AhlborgMandy}, pages = 175, publisher = {Infinite Science Publishing}, title = {The Influence of Trajectory and System Matrix Overlap on Image Reconstruction Results in Magnetic Particle Imaging}, year = 2016 }
• Kaethner, C., Erb, W., Ahlborg, M., Szwargulski, P., Knopp, T. and Buzug, T. M.: Non-Equispaced System Matrix Acquisition for Magnetic Particle Imaging based on Lissajous Node Points, IEEE Transactions on Medical Imaging, PP(99), 1–1, 2016, DOI: 10.1109/TMI.2016.2580458.
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  • [ URL ]
  @article{7490369, abstract = {Magnetic Particle Imaging (MPI) is an emerging technology in the field of (pre)clinical imaging. The acquisition of a particle signal is realized along specific sampling trajectories covering a defined field of view (FOV). In a system matrix (SM) based reconstruction procedure, the commonly used acquisition path in MPI is a Lissajous trajectory. Such a trajectory features an inhomogeneous coverage of the FOV, i.e. the center region is sampled less dense than the regions towards the edges of the FOV. Conventionally, the respective SM acquisition and the subsequent reconstruction do not reflect this inhomogeneous coverage. Instead, they are performed on an equispaced grid. The objective of this work is to introduce a sampling grid that inherently features the aforementioned inhomogeneity by using node points of Lissajous trajectories. Paired with a tailored polynomial interpolation of the reconstructed MPI signal, the entire image can be recovered. It is the first time that such a trajectory related non-equispaced grid is used for image reconstruction on simulated and measured MPI data and it is shown that the number of sampling positions can be reduced, while the spatial resolution remains constant.}, author = {Kaethner, C. and Erb, W. and Ahlborg, M. and Szwargulski, P. and Knopp, T. and Buzug, T. M.}, journal = {IEEE Transactions on Medical Imaging}, keywords = {buzugthorsten}, number = 99, pages = {1-1}, title = {Non-Equispaced System Matrix Acquisition for Magnetic Particle Imaging based on Lissajous Node Points}, volume = {PP}, year = 2016 }
• Cordes, A., Kaethner, C., Ahlborg, M. and Buzug, T. M.: X-space Deconvolution for Multidimensional Lissajous-based Data- Acquisition Schemes, 74, 2016.
  • [ BibTeX ]
  @inproceedings{cordes2016xspace, author = {Cordes, Aileen and Kaethner, Christian and Ahlborg, Mandy and Buzug, Thorsten M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {AhlborgMandy}, pages = 74, title = {X-space Deconvolution for Multidimensional Lissajous-based Data- Acquisition Schemes}, year = 2016 }
• Maass, M., Bente, K., Ahlborg, M., Medimagh, H., Phan, H., Buzug, T. M. and Mertins, A.: Optimized Compression of MPI System Matrices Using a Symmetry-Preserving Secondary Orthogonal Transform, International Journal on Magnetic Particle Imaging, 2(1), 1607002, 2016, DOI: 10.18416/ijmpi.2016.1607002.
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  • [ URL ]
  @article{maass2016optimized, author = {Maass, Marco and Bente, Klaas and Ahlborg, Mandy and Medimagh, Hanne and Phan, Huy and Buzug, Thorsten M. and Mertins, Alfred}, journal = {International Journal on Magnetic Particle Imaging}, keywords = {buzugthorsten}, number = 1, pages = 1607002, title = {Optimized Compression of MPI System Matrices Using a Symmetry-Preserving Secondary Orthogonal Transform}, volume = 2, year = 2016 }
• Ahlborg, M., Kaethner, C., Knopp, T., Szwargulski, P. and Buzug, T. M.: Using data redundancy gained by patch overlaps to reduce truncation artifacts in magnetic particle imaging, Physics in Medicine and Biology, 61(12), 4583, 2016, DOI: 10.1088/0031-9155/61/12/4583.
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  @article{0031-9155-61-12-4583, abstract = {The imaging technology magnetic particle imaging allows the detection of magnetic material, in particular superparamagnetic nanoparticles, by remagnetization of the material via magnetic fields. The application is aimed at medical imaging where the particles are applied as tracer directly into the blood stream. Medical safety considerations such as peripheral nerve stimulation limit the maximal amplitude of the magnetic fields and in turn the field of view size. To handle this constraint the concept of patches was introduced, which allows a shift of a field of view to different positions in order to enlarge the imaging area. If this is done statically an overlap of patches can be used to reduce truncation artifacts occurring at the adjacent edges. In this contribution, a differentiation of two different kinds of patch overlaps, i.e. a trajectory and a system matrix overlap, is made. Further, different concepts to combine the resulting redundant information are investigated with respect to the reduction of truncation artifacts. The methods are analyzed in detail in a simulation study and validated on experimental data.}, author = {Ahlborg, M and Kaethner, C and Knopp, T and Szwargulski, P and Buzug, T M}, journal = {Physics in Medicine and Biology}, keywords = {buzugthorsten}, number = 12, pages = 4583, title = {Using data redundancy gained by patch overlaps to reduce truncation artifacts in magnetic particle imaging}, volume = 61, year = 2016 }

• v. Gladiß, A., Gräfe, K., Ahlborg, M. and Buzug, T.: Undersampling the system matrix of a single sided MPI-scanner, 2015, DOI: 10.1109/IWMPI.2015.7107021.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Gladiss2015b, author = {{v. Gladiß}, A. and Gräfe, K. and Ahlborg, M. and Buzug, T.M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {AhlborgMandy}, publisher = {IEEE Xplore}, title = {Undersampling the system matrix of a single sided MPI-scanner}, year = 2015 }
• Szwargulski, P., Rahmer, J., Ahlborg, M., Kaethner, C. and Buzug, T. M.: Experimental Evaluation of Different Weighting Schemes in Magnetic Particle Imaging Reconstruction, Current Directions in Biomedical Engineering 2015, 1(1), 206–209, 2015, DOI: 10.1515/CDBME-2015-0052.
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  @article{Szwargulski2015e, author = {Szwargulski, P. and Rahmer, J. and Ahlborg, M. and Kaethner, C. and Buzug, T. M.}, journal = {Current Directions in Biomedical Engineering 2015}, keywords = {AhlborgMandy}, number = 1, pages = {206-209}, title = {Experimental Evaluation of Different Weighting Schemes in Magnetic Particle Imaging Reconstruction}, volume = 1, year = 2015 }
• Medimagh, H., Weissert, P., Bringout, G., Bente, K., Weber, M., Gräfe, K., Cordes, A. and Buzug, T.: Artifacts in field free line magnetic particle imaging in the presence of inhomogeneous and nonlinear magnetic fields, Current Directions in Biomedical Engineering, 1(1), 245–248, 2015, DOI: 10.1515/cdbme-2015-0061.
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  • [ URL ]
  @article{Medimagh2015c, author = {Medimagh, H. and Weissert, P. and Bringout, G. and Bente, K. and Weber, M. and Gräfe, K. and Cordes, A. and Buzug, T.M.}, journal = {Current Directions in Biomedical Engineering}, keywords = {BringoutGael}, number = 1, pages = {245-248}, title = {Artifacts in field free line magnetic particle imaging in the presence of inhomogeneous and nonlinear magnetic fields}, volume = 1, year = 2015 }
• Omer, O., Medimagh, H. and Buzug, T.: High resolution magnetic particle imaging with low density trajectory, 2015, DOI: 10.1109/IWMPI.2015.7106995.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Omer2015a, abstract = {The spatial resolution is an important factor in MPI. The trajectory density is one of many parameters affecting the spatial resolution of MPI. To obtain a high-resolution (HR) concentration one can increase the trajectory density or increase particle diameters. However, increasing the trajectory density leads to increase of the computational complexity. Also, large particles suffer from relaxation effects. In addition, imaging with system matrix that exhibits high grid leads to higher resolution but requires much calibration time for the system matrix. This work suggests to use small particle diameters with low density trajectory while sampling with low dimension system matrix and fuses these low-resolution (LR) concentrations as a post process to get HR concentrations.}, author = {Omer, O.A. and Medimagh, H. and Buzug, T.M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {MedimaghHanne}, month = {03}, title = {High resolution magnetic particle imaging with low density trajectory}, year = 2015 }
• Kaethner, C., Ahlborg, M., Bringout, G., Weber, M. and Buzug, T.: Axially Elongated Field-Free Point Data Acquisition in Magnetic Particle Imaging, IEEE Transactions on Medical Imaging, 34(2), 381–387, 2015, DOI: 10.1109/TMI.2014.2357077.
  • [ BibTeX ]
  • [ URL ]
  @article{Kaethner2015a, abstract = {The magnetic particle imaging (MPI) technology is a new imaging technique featuring an excellent possibility to detect iron oxide based nanoparticle accumulations in vivo. The excitation of the particles and in turn the signal generation in MPI are achieved by using oscillating magnetic fields. In order to realize a spatial encoding, a field-free point (FFP) is steered through the field of view (FOV). Such a positioning of the FFP can thereby be achieved by mechanical or electromagnetical movement. Conventionally, the data acquisition path is either a planar 2-D or a 3-D FFP trajectory. Assuming human applications, the size of the FOV sampled by such trajectories is strongly limited by heating of the body and by nerve stimulations. In this work, a new approach acquiring MPI data based on the axial elongation of a 2-D FFP trajectory is proposed. It is shown that such an elongation can be used as a data acquisition path to significantly increase the acquisition speed, with negligible loss of spatial resolution.}, author = {Kaethner, C. and Ahlborg, M. and Bringout, G. and Weber, M. and Buzug, T.M.}, journal = {IEEE Transactions on Medical Imaging}, keywords = {BringoutGael}, month = {02}, number = 2, pages = {381-387}, title = {Axially Elongated Field-Free Point Data Acquisition in Magnetic Particle Imaging}, volume = 34, year = 2015 }
• Medimagh, H., Weissert, P., Bringout, G., Bente, K., Weber, M., Gräfe, K., Cordes, A. and Buzug, T. M.: Artifacts in Field Free Line Magnetic Particle Imaging in the Presence of Inhomogeneous and Nonlinear Magnetic Fields, 2015.
  • [ BibTeX ]
  @inproceedings{Medimagh2015b, author = {Medimagh, H. and Weissert, P. and Bringout, G. and Bente, K. and Weber, M. and Gräfe, K. and Cordes, A. and Buzug, T. M.}, booktitle = {Deutsche Gesellschaft für Biomedizinische Technik Jahrestagung}, keywords = {BringoutGael}, title = {Artifacts in Field Free Line Magnetic Particle Imaging in the Presence of Inhomogeneous and Nonlinear Magnetic Fields}, volume = 60, year = 2015 }
• Kaethner, C., Ahlborg, M. and Buzug, T.: Focus field based trajectory elongation in MPI, 2015, DOI: 10.1109/IWMPI.2015.7107019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Kaethner2015c, abstract = {In Magnetic Particle Imaging (MPI), the data acquisition can be performed by steering a field-free point (FFP) through the field of view (FOV). When using drive fields to achieve the FFP movement, a fast spatial encoding of the FOV is enabled. Due to safety limits, in terms of patient heating and nerve stimulation, the amplitude of the applied currents needs to be small, which results in a small FOV. In order to enlarge the FOV, focus fields featuring a high amplitude and a low frequency can be used. In this contribution, an approach based on a linear focus field shift, which enlarges the FOV in axial direction, is proposed. Such a shift results in an elongation of a planar two-dimensional trajectory that features a controlled sub-sampling of the FOV.I Results show that a focus field based trajectory elongation in axial direction is a suitable data acquisition for MPI. In addition to this, the use of self-intersection points as trajectory specific axial distance measure has been proposed.}, author = {Kaethner, C. and Ahlborg, M. and Buzug, T.M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {AhlborgMandy}, month = {03}, title = {Focus field based trajectory elongation in MPI}, year = 2015 }
• Medimagh, H., Weissert, P., Bringout, G., Bente, K., Weber, M., Gräfe, K., Cordes, A. and Buzug, T.: Artifacts in field free line magnetic particle imaging, 2015, DOI: 10.1109/IWMPI.2015.7107043.
  • [ BibTeX ]
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  @inproceedings{Medimagh2015a, abstract = {Field Free Line (FFL) Magnetic Particle Imaging (MPI) allows for system function [1] or Radon based [2] image reconstruction and for projection imaging [3]. In light of efforts to scale up imaging systems (e.g. from mouse/rat size [3-6] to rabbit size [7]) and/or to increase the size of the field of view (FOV) compared to the bore of the scanner [8], the question gains in importance how the imaging process is affected by magnetic field inhomogeneities and gradient field nonlinearities, which may deform the FFL compared to an FFL produced by idealized homogeneous/linear magnetic fields. Moreover, truncation effects are an important aspect that has so far not been studied in FFL MPI. This contribution presents initial results of a comprehensive simulation study comparing Radon based and system function based image reconstruction in FFL MPI, both under idealized field conditions and in the presence of magnetic field inhomogeneities and gradient field nonlinearities.}, author = {Medimagh, H. and Weissert, P. and Bringout, G. and Bente, K. and Weber, M. and Gräfe, K. and Cordes, A. and Buzug, T.M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {BringoutGael}, month = {03}, title = {Artifacts in field free line magnetic particle imaging}, year = 2015 }
• von Gladiß, A., Ahlborg, M., Knopp, T. and Buzug, T.: Compressed Sensing of the System Matrix and Sparse Reconstruction of the Particle Concentration in Magnetic Particle Imaging, IEEE Transactions on Magnetics, 51(2), 6501304, 2015, DOI: 10.1109/TMAG.2014.2326432.
  • [ BibTeX ]
  • [ URL ]
  @article{Gladiss2015a, abstract = {The reconstruction of a particle concentration in magnetic particle imaging is commonly based on using a system matrix, whose acquisition is time consuming and whose storing is challenging. It has been shown recently that the acquisition time can be reduced with methods of compressed sensing and storage requirements can be reduced by storing in sparse representation. To improve the reconstruction, signals of low signal-to-noise ratio (SNR) are discarded. The determination of the SNR is difficult for undersampled signals. In this paper, the mixing order of the acquired harmonics is calculated to estimate the SNR. The spatial resolution of a system matrix can be increased by compressed sensing. A system matrix of small spatial resolution can be fully acquired in the same amount of time as a high resoluted system matrix that is undersampled correspondingly.}, author = {von Gladiß, A. and Ahlborg, M. and Knopp, T. and Buzug, T.M.}, journal = {IEEE Transactions on Magnetics}, keywords = {AhlborgMandy}, month = {02}, number = 2, pages = 6501304, title = {Compressed Sensing of the System Matrix and Sparse Reconstruction of the Particle Concentration in Magnetic Particle Imaging}, volume = 51, year = 2015 }

• Wojtczyk, H., Bringout, G., Tenner, W., Graeser, M., Grüttner, M., Sattel, T., Gräfe, K. and Buzug, T.: Toward the Optimization of D-Shaped Coils for the Use in an Open Magnetic Particle Imaging Scanner, IEEE Transactions on Magnetics, 50(7), 5100507, 2014, DOI: 10.1109/TMAG.2014.2303113.
  • [ BibTeX ]
  • [ URL ]
  @article{Wojtczyk2014a, abstract = {Magnetic particle imaging (MPI) is a novel medical imaging modality that allows for the quantitative detection of superparamagnetic iron oxide nanoparticles using static and oscillating magnetic fields. Essential aspects in the coil optimization for MPI include the magnetic field generated per unit current and the magnetic field homogeneity. For a set of D-shaped coils, which can be used in an open MPI scanner with lateral patient access to enable multidimensional imaging, these quantities were analyzed for a range of configurations. The results were compared with the situation in a four-wire-model and a four-wire-model with return paths (called eight-wire-model). It was found that for large coil radii, the effects of the D-coil set resemble those of the eight-wire-model; however, the local minimum in the magnetic field inhomogeneity is less pronounced.}, author = {Wojtczyk, H. and Bringout, G. and Tenner, W. and Graeser, M. and Grüttner, M. and Sattel, T.F. and Gräfe, K. and Buzug, T.M.}, journal = {IEEE Transactions on Magnetics}, keywords = {BringoutGael}, month = {07}, number = 7, pages = 5100507, title = {Toward the Optimization of D-Shaped Coils for the Use in an Open Magnetic Particle Imaging Scanner}, volume = 50, year = 2014 }
• Kaethner, C., Ahlborg, M., Knopp, T., Sattel, T. F. and Buzug, T. M.: Efficient gradient field generation providing a multi-dimensional arbitrary shifted field-free point for magnetic particle imaging, Journal of Applied Physics, 115(4), 044910, 2014, DOI: 10.1063/1.4863177.
  • [ BibTeX ]
  • [ URL ]
  @article{Kaethner2014d, abstract = {Magnetic Particle Imaging (MPI) is a tomographic imaging modality capable to visualize tracers using magnetic fields. A high magnetic gradient strength is mandatory, to achieve a reasonable image quality. Therefore, a power optimization of the coil configuration is essential. In order to realize a multi-dimensional efficient gradient field generator, the following improvements compared to conventionally used Maxwell coil configurations are proposed: (i) curved rectangular coils, (ii) interleaved coils, and (iii) multi-layered coils. Combining these adaptions results in total power reduction of three orders of magnitude, which is an essential step for the feasibility of building full-body human MPI scanners.}, author = {Kaethner, Christian and Ahlborg, Mandy and Knopp, Tobias and Sattel, Timo F. and Buzug, Thorsten M.}, journal = {Journal of Applied Physics}, keywords = {AhlborgMandy}, number = 4, pages = {044910}, title = {Efficient gradient field generation providing a multi-dimensional arbitrary shifted field-free point for magnetic particle imaging}, volume = 115, year = 2014 }
• Omer, O., Wojtczyk, H. and Buzug, T.: Simultaneous Reconstruction and Resolution Enhancement for Magnetic Particle Imaging, IEEE Transactions on Magnetics, 51(2), 6500804, 2014, DOI: 10.1109/TMAG.2014.2330553.
  • [ BibTeX ]
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  @article{Omer2014b, abstract = {Spatial resolution is an essential parameter for magnetic particle imaging (MPI). The spatial resolution of MPI depends, among other things, on the particles diameter and sampling frequency. The spatial resolution increases when increasing the particle diameter. However, large particles suffer from relaxation effects and are not preferred in some applications. On the other hand, spatial resolution increases with the sampling frequency, which in turn increases the number of sampling points. As an alternative solution for resolution enhancement, super-resolution (SR) is proved to be beneficial in improving the image quality of many medical imaging systems without the need for significant hardware alteration. In this paper, we propose to use small particle diameter and low sampling frequency to obtain multiple low-resolution (LR) magnetic particle measurements and apply a resolution enhancement technique to reconstruct a higher resolution magnetic particle concentration. Unlike the conventional SR techniques, we propose to reconstruct a high-resolution concentration from the measured LR signals instead of reconstructing LR concentrations and then post-process these concentrations to get a higher resolution concentration. Simulation results show that the resolution of MPI can be increased by incorporating resolution enhancement technique without increasing the particle diameter. In addition, simulation results show that using simultaneous reconstruction and resolution enhancement results in sharper concentrations and that this procedure is more robust against noise than using SR as a post-process.}, author = {Omer, O.A. and Wojtczyk, H. and Buzug, T.M.}, journal = {IEEE Transactions on Magnetics}, keywords = {MedimaghHanne}, month = {02}, number = 2, pages = 6500804, title = {Simultaneous Reconstruction and Resolution Enhancement for Magnetic Particle Imaging}, volume = 51, year = 2014 }
• Bente, K., Weber, M., Graeser, M., Sattel, T. F., Erbe, M. and Buzug, T. M.: Electronic Field Free Line Rotation and Relaxation Deconvolution in Magnetic Particle Imaging, IEEE Transactions on Medical Imaging, 34(2), 644–651, 2014, DOI: 10.1109/TMI.2014.2364891.
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  @article{Bente2014a, abstract = {It has been shown that magnetic particle imaging (MPI), an imaging method suggested in 2005, is capable of measuring the spatial distribution of magnetic nanoparticles. Since the particles can be administered as biocompatible suspensions, this method promises to perform well as a tracer-based medical imaging technique. It is capable of generating real-time images, which will be useful in interventional procedures, without utilizing any harmful radiation. To obtain a signal from the administered superparamagnetic iron oxide (SPIO) particles, a sinusoidal changing external homogeneous magnetic field is applied. To achieve spatial encoding, a gradient field is superimposed. Conventional MPI works with a spatial encoding field that features a field free point (FFP). To increase sensitivity, an improved spatial encoding field, featuring a field free line (FFL) can be used. Previous FFL scanners, featuring a 1-D excitation, could demonstrate the feasibility of the FFL-based MPI imaging process. In this work, an FFL-based MPI scanner is presented that features a 2-D excitation field and, for the first time, an electronic rotation of the spatial encoding field. Furthermore, the role of relaxation effects in MPI is starting to move to the center of interest. Nevertheless, no reconstruction schemes presented thus far include a dynamical particle model for image reconstruction. A first application of a model that accounts for relaxation effects in the reconstruction of MPI images is presented here in the form of a simplified, but well performing strategy for signal deconvolution. The results demonstrate the high impact of relaxation deconvolution on the MPI imaging process.}, author = {Bente, K. and Weber, M. and Graeser, M. and Sattel, T. F. and Erbe, M. and Buzug, T. M.}, journal = {IEEE Transactions on Medical Imaging}, keywords = {WeberMatthias}, month = {02}, number = 2, pages = {644-651}, title = {Electronic Field Free Line Rotation and Relaxation Deconvolution in Magnetic Particle Imaging}, volume = 34, year = 2014 }
• Ahlborg, M., Knopp, T. and Buzug, T. M.: Comparison of X-Space and Chebychev Reconstruction in Magnetic Particle Imaging, 104–105, 2014.
  • [ BibTeX ]
  @inproceedings{Ahlborg2014a, author = {Ahlborg, Mandy and Knopp, Tobias and Buzug, Thorsten M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {AhlborgMandy}, pages = {104-105}, title = {Comparison of X-Space and Chebychev Reconstruction in Magnetic Particle Imaging}, year = 2014 }
• Omer, O. A., Wojtczyk, H. and Buzug, T. M.: Simultaneous Reconstruction and Resolution Enhancement for Magnetic Particle Imaging, 28–29, 2014.
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  @inproceedings{Omer2014a, author = {Omer, Osama A. and Wojtczyk, Hanne and Buzug, Thorsten M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, editor = {Buzug, Thorsten M. and Borgert, Joern}, keywords = {MedimaghHanne}, pages = {28-29}, title = {Simultaneous Reconstruction and Resolution Enhancement for Magnetic Particle Imaging}, year = 2014 }
• Kaethner, C., Knopp, T., Ahlborg, M., Sattel, T. F. and Buzug, T. M.: Efficient Gradient Fields in Magnetic Particle Imaging - From One Dimension to Multiple Dimensions, 72–73, 2014.
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  @inproceedings{Kaethner2014c, author = {Kaethner, C. and Knopp, T. and Ahlborg, M. and Sattel, T. F. and Buzug, T. M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {AhlborgMandy}, pages = {72-73}, title = {Efficient Gradient Fields in Magnetic Particle Imaging - From One Dimension to Multiple Dimensions}, year = 2014 }
• Kleine, M., v. Gladiß, A. and Buzug, T. M.: Iterative Hard Thresholding for the Reconstruction of an Undersampled System Matrix in Magnetic Particle Imaging, 628–632, 2014, DOI: 10.1515/bmt-2014-5008.
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  @inproceedings{Kleine2014, author = {Kleine, Matthias and {v. Gladiß}, A. and Buzug, Thorsten M.}, booktitle = {Deutsche Gesellschaft für Biomedizinische Technik Jahrestagung}, keywords = {IMT}, pages = {628-632}, title = {Iterative Hard Thresholding for the Reconstruction of an Undersampled System Matrix in Magnetic Particle Imaging}, volume = {59, Suppl. 1}, year = 2014 }

• Timmermeyer, A., Wojtczyk, H., Tenner, W., Bringout, G., Grüttner, M., Graeser, M., Sattel, T., Halkola, A. and Buzug, T.: Super-resolution approaches for resolution enhancement in magnetic particle imaging, 2013, DOI: 10.1109/IWMPI.2013.6528360.
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  @inproceedings{Timmermeyer2013a, abstract = {Given a definition of spatial resolution that considers two objects as distinguished if the minimum value of the gap is less than 50% of the value at the object position [7], both approaches achieved an improvement of the spatial resolution in the 1D simulation study as visualized in Fig. 1 and 2. If the spatial resolution is considered as the minimum width of two distinguished lines, the first approach using spatially shifted images achieved a spatial resolution of 1.7 mm and the second approach using different sampling points achieved a resolution of 2.6 mm. This is an improvement in comparison to the used low resolution images with a spatial resolution of 2 mm (first approach) and 2.9 mm (second approach).}, author = {Timmermeyer, A. and Wojtczyk, H. and Tenner, W. and Bringout, G. and Grüttner, M. and Graeser, M. and Sattel, T. and Halkola, A. and Buzug, T.M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {BringoutGael}, month = {03}, title = {Super-resolution approaches for resolution enhancement in magnetic particle imaging}, year = 2013 }
• Wojtczyk, H., Bringout, G., Tenner, W., Graeser, M., Grüttner, M., Sattel, T., Gräfe, K., Haegele, J., Duschka, R., Panagiotopoulos, N., Vogt, F., Barkhausen, J. and Buzug, T.: Comparison of Open Scanner Designs for Interventional Magnetic Particle Imaging, 2013, DOI: 10.1515/bmt-2013-4279.
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  @inproceedings{Wojtczyk2013b, author = {Wojtczyk, H. and Bringout, G. and Tenner, W. and Graeser, M. and Grüttner, M. and Sattel, T.F. and Gräfe, K. and Haegele, J. and Duschka, R.L. and Panagiotopoulos, N. and Vogt, F.M. and Barkhausen, J. and Buzug, T.M.}, booktitle = {Deutsche Gesellschaft für Biomedizinische Technik Jahrestagung}, keywords = {BringoutGael}, title = {Comparison of Open Scanner Designs for Interventional Magnetic Particle Imaging}, volume = 58, year = 2013 }
• Grüttner, M., Knopp, T., Franke, J., Heidenreich, M., Rahmer, J., Halkola, A., Kaethner, C., Borgert, J. and Buzug, T.: On the formulation of the image reconstruction problem in magnetic particle imaging, Biomedizinische Technik / Biomedical Engineering, 58(6), 583–591, 2013, DOI: 10.1515/bmt-2012-0063.
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  @article{Gruettner2013c, author = {Grüttner, M. and Knopp, T. and Franke, J. and Heidenreich, M. and Rahmer, J. and Halkola, A. and Kaethner, C. and Borgert, J. and Buzug, T.M.}, booktitle = {Biomedizinische Technik / Biomedical Engineering}, keywords = {AhlborgMandy}, number = 6, pages = {583-591}, title = {On the formulation of the image reconstruction problem in magnetic particle imaging}, volume = 58, year = 2013 }
• Wojtczyk, H., Timmermeyer, A., Tenner, W., Sattel, T., Bringout, G., Grüttner, M., Graeser, M. and Buzug, T.: Measure of trajectory quality in Magnetic Particle Imaging, 2013, DOI: 10.1109/IWMPI.2013.6528351.
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  @inproceedings{Wojtczyk2013a, abstract = {For all trajectories, the energies computed in time and frequency domain agree well. The maximum local magnetization change dM/dt is largest for the spiral and Lissajous trajectories while it is smallest for the Cartesian trajectory. For the Lissajous and Cartesian trajectories, the total magnetization change appears more homogeneous over the field of view (FOV) than for the radial and spiral trajectories, where it is stronger in the center compared to the borders. In general, areas of homogeneous high total magnetization change seem to correspond to areas of high spatial resolution in reconstructed images.}, author = {Wojtczyk, H. and Timmermeyer, A. and Tenner, W. and Sattel, T.F. and Bringout, G. and Grüttner, M. and Graeser, M. and Buzug, T.M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {BringoutGael}, month = {03}, title = {Measure of trajectory quality in Magnetic Particle Imaging}, year = 2013 }
• Timmermeyer, A., Wojtczyk, H., Tenner, W., Bringout, G., Grüttner, M., Graeser, M., Sattel, T. F., Halkola, A. and Buzug, T. M.: Super-resolution approach in magnetic particle imaging – Evaluation of effectiveness at various noise levels, 2013.
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  @inproceedings{Timmermeyer2013b, author = {Timmermeyer, Anja and Wojtczyk, Hanne and Tenner, Wiebke and Bringout, Gael and Grüttner, Mandy and Graeser, Matthias and Sattel, Timo F. and Halkola, Aleksi and Buzug, Thorsten M.}, booktitle = {Proceedings der 44. Jahrestagung der Deutschen Gesellschaft für Medizinische Physik}, editor = {Treuer, Harald}, keywords = {BringoutGael}, title = {Super-resolution approach in magnetic particle imaging – Evaluation of effectiveness at various noise levels}, year = 2013 }
• Grüttner, M., Sattel, T., Bringout, G., Graeser, M., Tenner, W., Wojtczyk, H. and Buzug, T.: Truncation artifacts in Magnetic Particle Imaging, 2013, DOI: 10.1109/IWMPI.2013.6528335.
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  @inproceedings{Gruettner2013b, abstract = {Figure 1 clearly shows the effect of truncation artifacts when particles are not covered by the trajectory. With the removal of edge pixels these artifacts disappear. However, some information of the image is lost depending on the size of the necessary cut-off. With the multi-resolution approach the full information is used. Instead of removing pixels they are combined to large pixels. This method results in a better quality with small cut-offs compared to the non-compensated images.}, author = {Grüttner, M. and Sattel, T.F. and Bringout, G. and Graeser, M. and Tenner, W. and Wojtczyk, H. and Buzug, T.M.}, booktitle = {International Workshop on Magnetic Particle Imaging}, keywords = {BringoutGael}, month = {03}, title = {Truncation artifacts in Magnetic Particle Imaging}, year = 2013 }

• Grüttner, M., Sattel, T., Graeser, M., Wojtczyk, H., Bringout, G., Tenner, W. and Buzug, T.: Enlarging the Field of View in Magnetic Particle Imaging – A Comparison, 249–253, 2012, DOI: 10.1007/978-3-642-24133-8_40.
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  @inproceedings{Gruettner2012a, author = {Grüttner, M. and Sattel, T.F. and Graeser, M. and Wojtczyk, H. and Bringout, G. and Tenner, W. and Buzug, T.M.}, booktitle = {Springer Proceedings in Physics}, editor = {Buzug, Thorsten M. and Borgert, Jörn}, keywords = {BringoutGael}, pages = {249-253}, publisher = {Springer Berlin Heidelberg}, series = {Springer Proceedings in Physics}, title = {Enlarging the Field of View in Magnetic Particle Imaging – A Comparison}, volume = 140, year = 2012 }
• Wojtczyk, H., Haegele, J., Grüttner, M., Tenner, W., Bringout, G., Graeser, M., Vogt, F., Barkhausen, J. and Buzug, T.: Visualization of Instruments in interventional Magnetic Particle Imaging (iMPI): A Simulation Study on SPIO Labelings, 167–172, 2012, DOI: 10.1007/978-3-642-24133-8_27.
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  @inproceedings{Wojtczyk2012a, author = {Wojtczyk, Hanne and Haegele, Julian and Grüttner, Mandy and Tenner, Wiebke and Bringout, Gael and Graeser, Matthias and Vogt, FlorianM. and Barkhausen, Jörg and Buzug, ThorstenM.}, booktitle = {Springer Proceedings in Physics}, editor = {Buzug, Thorsten M. and Borgert, Jörn}, keywords = {BringoutGael}, pages = {167-172}, publisher = {Springer Berlin Heidelberg}, series = {Springer Proceedings in Physics}, title = {Visualization of Instruments in interventional Magnetic Particle Imaging (iMPI): A Simulation Study on SPIO Labelings}, volume = 140, year = 2012 }
• Griese, F., Grüttner, M. and Buzug, T.: Extended Field of View in Magnetic Particle Imaging, 755, 2012, DOI: 10.1515/bmt-2012-4083.
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  @inproceedings{Griese:2012, author = {Griese, F. and Grüttner, M. and Buzug, T.M.}, booktitle = {Deutsche Gesellschaft für Biomedizinische Technik Jahrestagung}, keywords = {AhlborgMandy}, pages = 755, title = {Extended Field of View in Magnetic Particle Imaging}, volume = 57, year = 2012 }

• Grüttner, M., Graeser, M., Biederer, S., Sattel, T., Wojtczyk, H., Tenner, W., Knopp, T., Gleich, B., Borgert, J. and Buzug, T.: 1D-image reconstruction for magnetic particle imaging using a hybrid system function, 2545–2548, 2011, DOI: 10.1109/NSSMIC.2011.6152687.
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  @inproceedings{Gruettner2011, abstract = {Magnetic Particle Imaging is a promising imaging technique using iron-oxide nanoparticle tracers. The spatial distribution of these particles can be determined by solving a system of linear equations. This reconstruction is based on a system function that either has to be measured or can be calculated with given information about scanner topology and particle characteristics. This paper introduces a new approach combining both possibilities. A Magnetic Particle Spectrometer is used to obtain a hybrid system function. Furthermore, we will show that the hybrid system function can be successfully used for 1D-image reconstruction and potentially is an alternative to the measurement-based system function.}, author = {Grüttner, M. and Graeser, M. and Biederer, S. and Sattel, T.F. and Wojtczyk, H. and Tenner, W. and Knopp, T. and Gleich, B. and Borgert, J. and Buzug, T.M.}, booktitle = {Nuclear Science Symposium and Medical Imaging Conference}, keywords = {AhlborgMandy}, month = 10, pages = {2545-2548}, title = {1D-image reconstruction for magnetic particle imaging using a hybrid system function}, year = 2011 }