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Item type:Publication, Access status: without files , In vitro and in vivo comparison of a tailored magnetic particle imaging blood pool tracer with Resovist(Jenny Stanford Publishing, 2026-01-01); ; ; ; Optimizing tracers for individual imaging techniques is an active field of research. The purpose of this study was to perform in vitro and in vivo magnetic particle imaging (MPI) measurements using a new monodisperse and size-optimized tracer, LS-008, and to compare it with the performance of Resovist, the standard MPI tracer.Publicationtype: Book Part6 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , In vitro detection of gastrointestinal bleeding using single- and multi-contrast MPI(Infinite Science Publishing, 2024-03-10); ; ; ; Gastrointestinal (GI) bleeding is a potentially life-threatening condition that is typically diagnosed using radiation-based imaging modalities such as computed tomography (CT) or catheter-based angiography. Magnetic Particle Imaging (MPI) could provide non-invasive, real-time volumetric imaging without ionizing radiation in future human-sized scanners that covers the entire GI tract. We have developed a human-sized (3D printed) phantom that represents both the bowel lumen and the vascular compartment of the bowel wall. One version has a perforation between the two compartments and a control phantom does not. For single contrast MPI, we evaluate the fluid exchange between the two lumen by observing an administered blood pool tracer. For multi-contrast MPI, the intestinal lumen was filled with an intestinal tracer, which represents an orally administered tracer, to allow co-registration of both tracers at the same location. Both single-and multi-contrast MPI are feasible to visualize GI bleeding and MPI may prove to be a useful tool for radiation-free detection of bleeding throughout the GI tract.Publicationtype: Journal Article4 14 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Real-time multi-contrast magnetic particle imaging for the detection of gastrointestinal bleeding(Nature Publishing Group, 2023-12-27); ; ; 7 42 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Pulmonary blood volume estimation in mice by magnetic particle imaging and magnetic resonance imaging(Macmillan Publishers Limited, part of Springer Nature, 2021-03-01); ; ; ; This methodical work describes the measurement and calculation of pulmonary blood volume in mice based on two imaging techniques namely by using magnetic particle imaging (MPI) and cardiac magnetic resonance imaging (MRI). Besides its feasibility aspects that may influence quantitative analysis are studied. Eight FVB mice underwent cardiac MRI to determine stroke volumes and anatomic MRI as morphological reference for functional MPI data. Arrival time analyses of boli of 1 µl of 1 M superparamagnetic tracer were performed by MPI. Pulmonary transit time of the bolus was determined by measurements in the right and left ventricles. Pulmonary blood volume was calculated out of stroke volume, pulmonary transit time and RR-interval length including a maximal error analysis. Cardiac stroke volume was 31.7 µl ± 2.3 µl with an ejection fraction of 71% ± 6%. A sharp contrast bolus profile was observed by MPI allowing subdividing the first pass into three distinct phases: tracer arrival in the right ventricle, pulmonary vasculature, and left ventricle. The bolus full width at half maximum was 578 ms ± 144 ms in the right ventricle and 1042 ms ± 150 ms in the left ventricle. Analysis of pulmonary transit time revealed 745 ms ± 81 ms. Mean RR-interval length was 133 ms ± 12 ms. Pulmonary blood volume resulted in 177 µl ± 27 µl with a mean maximal error limit of 27 µl. Non-invasive assessment of the pulmonary blood volume in mice was feasible. This technique can be of specific value for evaluation of pulmonary hemodynamics in mouse models of cardiac dysfunction or pulmonary disease. Pulmonary blood volume can complement cardiac functional parameters as a further hemodynamic parameter.Publicationtype: Journal ArticleScopus© Citations 12 53 135 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Volumetry in magnetic particle imaging(Infinite Science Publishing, 2020-09-02); ; ; ; In this work, we investigate the suitability of MPI as a volumetry tool for the determination of retrograde voiding cystography of the bladder. Measurements were performed in two different experimental coil settings: first with a novel gradiometer providing three orthogonal channels and second a single-channel gradiometer at varying gradient strengths. The volumes were calculated using two different approaches: a calibration approach based on the amount of SPIOs and a threshold approach. We show that with both approaches MPI volumetry is feasible. Finally we present initial in vivo results of a retrograde voiding cystography in rats.Publicationtype: Journal Article132 64 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , In vivo liver visualizations with magnetic particle imaging based on the calibration measurement approach(2017-04-05); ; ; ; Magnetic particle imaging (MPI) facilitates the rapid determination of 3D in vivo magnetic nanoparticle distributions. In this work, liver MPI following intravenous injections of ferucarbotran (Resovist®) was studied. The image reconstruction was based on a calibration measurement, the so called system function. The application of an enhanced system function sample reflecting the particle mobility and aggregation status of ferucarbotran resulted in significantly improved image reconstructions. The finding was supported by characterizations of different ferucarbotran compositions with the magnetorelaxometry and magnetic particle spectroscopy technique. For instance, similar results were obtained between ferucarbotran embedded in freeze-dried mannitol sugar and liver tissue harvested after a ferucarbotran injection. In addition, the combination of multiple shifted measurement patches for a joint reconstruction of the MPI data enlarged the field of view and increased the covering of liver MPI on magnetic resonance images noticeably.Publicationtype: Journal Article105 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , In vitro and in vivo comparison of a tailored magnetic particle imaging blood pool tracer with resovist(IOP Publishing, 2017-04-05); ; ; ; Optimizing tracers for individual imaging techniques is an active field of research. The purpose of this study was to perform in vitro and in vivo magnetic particle imaging (MPI) measurements using a new monodisperse and size-optimized tracer, LS-008, and to compare it with the performance of Resovist, the standard MPI tracer. Magnetic particle spectroscopy (MPS) and in vitro MPI measurements were performed in concerns of concentration and amount of tracer in a phantom. In vivo studies were carried out in healthy FVB mice. The first group (n = 3) received 60 μl LS-008 (87 mM) and the second (n = 3) diluted Resovist of the same concentration and volume. Tracer injections were performed with a syringe pump during a dynamic MPI scan. For anatomic referencing MRI was applied beforehand of the MPI measurements. Summing up MPS examinations and in vitro MPI experiments, LS-008 showed better sensitivity and spatial resolution than Resovist. In vivo both tracers can visualize the propagation of the bolus through the inferior vena cava. MPI with LS-008 did show less temporal fluctuation artifacts and the pulsation of blood due to respiratory and cardiac cycle was detectable. With LS-008 the aorta was distinguishable from the caval vein while with Resovist this failed. A liver vessel and a vessel structure leading cranially could only be observed with LS-008 and not with Resovist. Beside these structural advantages both tracers showed very different blood half-life. For LS-008 we found 88 min. Resovist did show a fast liver accumulation and a half-life of 13 min. Only with LS-008 the perfusion fraction in liver and kidney was measureable. MPI for angiography can be significantly improved by applying more effective tracers. LS-008 shows a clear improvement concerning the delineation while resolving a larger number of vessels in comparison to Resovist. Therefore, in aspects of quality and quantity LS-008 is clearly favorable for angiographic and perfusion studies.Publicationtype: Journal Article705 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Geometry planning and image registration in magnetic particle imaging using bimodal fiducial markers(2016-06-01); ; ; ; Purpose: Magnetic particle imaging (MPI) is a quantitative imaging modality that allows the distribution of superparamagnetic nanoparticles to be visualized. Compared to other imaging techniques like x-ray radiography, computed tomography (CT), and magnetic resonance imaging (MRI), MPI only provides a signal from the administered tracer, but no additional morphological information, which complicates geometry planning and the interpretation of MP images. The purpose of the authors study was to develop bimodal fiducial markers that can be visualized by MPI and MRI in order to create MP-MR fusion images. Methods: A certain arrangement of three bimodal fiducial markers was developed and used in a combined MRI/MPI phantom and also during in vivo experiments in order to investigate its suitability for geometry planning and image fusion. An algorithm for automated marker extraction in both MR and MP images and rigid registration was established. Results: The developed bimodal fiducial markers can be visualized by MRI and MPI and allow for geometry planning as well as automated registration and fusion of MRMP images. Conclusions: To date, exact positioning of the object to be imaged within the field of view (FOV) and the assignment of reconstructed MPI signals to corresponding morphological regions has been difficult. The developed bimodal fiducial markers and the automated image registration algorithm help to overcome these difficulties.Publicationtype: Journal Article129 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Geometrieplanung und Bildregistrierung mittels bimodaler Fiducial-Marker für Magnetic Particle Imaging(Springer, 2016-03); ; ; ; Publicationtype: Conference Paper282 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Sensitivity Enhancement in Magnetic Particle Imaging by Background Subtraction(2016-03); ; ; ; Biomedical applications such as cell tracking and angiography require the detection of low concentrations of superparamagnetic iron oxide nanoparticles (SPIOs) for imaging purposes. Magnetic particle imaging (MPI) is a new technology which enables the quantitative and time-resolved localization of SPIO distributions. However, the minimum concentration at which the SPIOs can be reconstructed with a suitable quality still remains to be investigated. In this work we examine the background signals in raw data that were measured without any SPIOs in the scanner tube. We show that a background subtraction in combination with a frequency cutoff for the dynamic part of the background signal lowers the detection limit for SPIOs in MPI up to a factor of ten. In-vivo mouse experiments show that for early time points from when the tracer enters the vena cava a reconstructed image of sufficient quality can only be obtained when a background subtraction is performed.Publicationtype: Journal Article173