TY - JOUR A1 - Vogel, Patrick A1 - Rückert, Martin Andreas A1 - Friedrich, Bernhard A1 - Tietze, Rainer A1 - Lyer, Stefan A1 - Kampf, Thomas A1 - Hennig, Thomas A1 - Dölken, Lars A1 - Alexiou, Christoph A1 - Behr, Volker Christian T1 - Critical Offset Magnetic PArticle SpectroScopy for rapid and highly sensitive medical point-of-care diagnostics JF - Nature Communications N2 - Magnetic nanoparticles (MNPs) have been adapted for many applications, e.g., bioassays for the detection of biomarkers such as antibodies, by controlled engineering of specific surface properties. Specific measurement of such binding states is of high interest but currently limited to highly sensitive techniques such as ELISA or flow cytometry, which are relatively inflexible, difficult to handle, expensive and time-consuming. Here we report a method named COMPASS (Critical-Offset-Magnetic-Particle-SpectroScopy), which is based on a critical offset magnetic field, enabling sensitive detection to minimal changes in mobility of MNP ensembles, e.g., resulting from SARS-CoV-2 antibodies binding to the S antigen on the surface of functionalized MNPs. With a sensitivity of 0.33 fmole/50 µl (≙7 pM) for SARS-CoV-2-S1 antibodies, measured with a low-cost portable COMPASS device, the proposed technique is competitive with respect to sensitivity while providing flexibility, robustness, and a measurement time of seconds per sample. In addition, initial results with blood serum demonstrate high specificity. KW - biochemical assays KW - characterization and analytical techniques KW - magnetic properties and materials KW - nanoparticles Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-300893 VL - 13 ER - TY - JOUR A1 - Aster, Hans-Christoph A1 - Evdokimov, Dimitar A1 - Braun, Alexandra A1 - Üçeyler, Nurcan A1 - Kampf, Thomas A1 - Pham, Mirko A1 - Homola, György A. A1 - Sommer, Claudia T1 - CNS imaging characteristics in fibromyalgia patients with and without peripheral nerve involvement JF - Scientific Reports N2 - We tested the hypothesis that reduced skin innervation in fibromyalgia syndrome is associated with specific CNS changes. This prospective case–control study included 43 women diagnosed with fibromyalgia syndrome and 40 healthy controls. We further compared the fibromyalgia subgroups with reduced (n = 21) and normal (n = 22) skin innervation. Brains were analysed for cortical volume, for white matter integrity, and for functional connectivity. Compared to controls, cortical thickness was decreased in regions of the frontal, temporal and parietal cortex in the fibromyalgia group as a whole, and decreased in the bilateral pericalcarine cortices in the fibromyalgia subgroup with reduced skin innervation. Diffusion tensor imaging revealed a significant increase in fractional anisotropy in the corona radiata, the corpus callosum, cingulum and fornix in patients with fibromyalgia compared to healthy controls and decreased FA in parts of the internal capsule and thalamic radiation in the subgroup with reduced skin innervation. Using resting-state fMRI, the fibromyalgia group as a whole showed functional hypoconnectivity between the right midfrontal gyrus and the posterior cerebellum and the right crus cerebellum, respectively. The subgroup with reduced skin innervation showed hyperconnectivity between the inferior frontal gyrus, the angular gyrus and the posterior parietal gyrus. Our results suggest that the subgroup of fibromyalgia patients with pronounced pathology in the peripheral nervous system shows alterations in morphology, structural and functional connectivity also at the level of the encephalon. We propose considering these subgroups when conducting clinical trials. KW - fibromyalgia syndrome KW - CNS imaging KW - peripheral nerve involvement Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-300562 VL - 12 IS - 1 ER - TY - JOUR A1 - Winter, Patrick M. A1 - Andelovic, Kristina A1 - Kampf, Thomas A1 - Hansmann, Jan A1 - Jakob, Peter Michael A1 - Bauer, Wolfgang Rudolf A1 - Zernecke, Alma A1 - Herold, Volker T1 - Simultaneous measurements of 3D wall shear stress and pulse wave velocity in the murine aortic arch JF - Journal of Cardiovascular Magnetic Resonance N2 - Purpose Wall shear stress (WSS) and pulse wave velocity (PWV) are important parameters to characterize blood flow in the vessel wall. Their quantification with flow-sensitive phase-contrast (PC) cardiovascular magnetic resonance (CMR), however, is time-consuming. Furthermore, the measurement of WSS requires high spatial resolution, whereas high temporal resolution is necessary for PWV measurements. For these reasons, PWV and WSS are challenging to measure in one CMR session, making it difficult to directly compare these parameters. By using a retrospective approach with a flexible reconstruction framework, we here aimed to simultaneously assess both PWV and WSS in the murine aortic arch from the same 4D flow measurement. Methods Flow was measured in the aortic arch of 18-week-old wildtype (n = 5) and ApoE\(^{−/−}\) mice (n = 5) with a self-navigated radial 4D-PC-CMR sequence. Retrospective data analysis was used to reconstruct the same dataset either at low spatial and high temporal resolution (PWV analysis) or high spatial and low temporal resolution (WSS analysis). To assess WSS, the aortic lumen was labeled by semi-automatically segmenting the reconstruction with high spatial resolution. WSS was determined from the spatial velocity gradients at the lumen surface. For calculation of the PWV, segmentation data was interpolated along the temporal dimension. Subsequently, PWV was quantified from the through-plane flow data using the multiple-points transit-time method. Reconstructions with varying frame rates and spatial resolutions were performed to investigate the influence of spatiotemporal resolution on the PWV and WSS quantification. Results 4D flow measurements were conducted in an acquisition time of only 35 min. Increased peak flow and peak WSS values and lower errors in PWV estimation were observed in the reconstructions with high temporal resolution. Aortic PWV was significantly increased in ApoE\(^{−/−}\) mice compared to the control group (1.7 ± 0.2 versus 2.6 ± 0.2 m/s, p < 0.001). Mean WSS magnitude values averaged over the aortic arch were (1.17 ± 0.07) N/m\(^2\) in wildtype mice and (1.27 ± 0.10) N/m\(^2\) in ApoE\(^{−/−}\) mice. Conclusion The post processing algorithm using the flexible reconstruction framework developed in this study permitted quantification of global PWV and 3D-WSS in a single acquisition. The possibility to assess both parameters in only 35 min will markedly improve the analyses and information content of in vivo measurements. KW - 4D flow KW - pulse wave velocity KW - wall shear stress KW - radial KW - self-navigation KW - mouse KW - aortic arch KW - atherosclerosis KW - mice KW - flow KW - plaque KW - CMR KW - quantification KW - microscopy Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-259152 VL - 23 IS - 1 ER - TY - JOUR A1 - Andelovic, Kristina A1 - Winter, Patrick A1 - Kampf, Thomas A1 - Xu, Anton A1 - Jakob, Peter Michael A1 - Herold, Volker A1 - Bauer, Wolfgang Rudolf A1 - Zernecke, Alma T1 - 2D Projection Maps of WSS and OSI Reveal Distinct Spatiotemporal Changes in Hemodynamics in the Murine Aorta during Ageing and Atherosclerosis JF - Biomedicines N2 - Growth, ageing and atherosclerotic plaque development alter the biomechanical forces acting on the vessel wall. However, monitoring the detailed local changes in wall shear stress (WSS) at distinct sites of the murine aortic arch over time has been challenging. Here, we studied the temporal and spatial changes in flow, WSS, oscillatory shear index (OSI) and elastic properties of healthy wildtype (WT, n = 5) and atherosclerotic apolipoprotein E-deficient (Apoe\(^{−/−}\), n = 6) mice during ageing and atherosclerosis using high-resolution 4D flow magnetic resonance imaging (MRI). Spatially resolved 2D projection maps of WSS and OSI of the complete aortic arch were generated, allowing the pixel-wise statistical analysis of inter- and intragroup hemodynamic changes over time and local correlations between WSS, pulse wave velocity (PWV), plaque and vessel wall characteristics. The study revealed converse differences of local hemodynamic profiles in healthy WT and atherosclerotic Apoe\(^{−/−}\) mice, and we identified the circumferential WSS as potential marker of plaque size and composition in advanced atherosclerosis and the radial strain as a potential marker for vascular elasticity. Two-dimensional (2D) projection maps of WSS and OSI, including statistical analysis provide a powerful tool to monitor local aortic hemodynamics during ageing and atherosclerosis. The correlation of spatially resolved hemodynamics and plaque characteristics could significantly improve our understanding of the impact of hemodynamics on atherosclerosis, which may be key to understand plaque progression towards vulnerability. KW - atherosclerosis KW - mouse KW - 4D flow MRI KW - aortic arch KW - flow dynamics KW - WSS KW - mapping KW - PWV KW - plaque characteristics Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-252164 SN - 2227-9059 VL - 9 IS - 12 ER - TY - JOUR A1 - Horvat, Sonja A1 - Vogel, Patrick A1 - Kampf, Thomas A1 - Brandl, Andreas A1 - Alshamsan, Aws A1 - Alhadlaq, Hisham A. A1 - Ahamed, Maqusood A1 - Albrecht, Krystyna A1 - Behr, Volker C. A1 - Beilhack, Andreas A1 - Groll, Jürgen T1 - Crosslinked Coating Improves the Signal‐to‐Noise Ratio of Iron Oxide Nanoparticles in Magnetic Particle Imaging (MPI) JF - ChemNanoMat N2 - Magnetic particle imaging is an emerging tomographic method used for evaluation of the spatial distribution of iron‐oxide nanoparticles. In this work, the effect of the polymer coating on the response of particles was studied. Particles with covalently crosslinked coating showed improved signal and image resolution. KW - crosslinked coating KW - imaging agents KW - magnetic properties KW - MPI KW - MPS Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-214718 VL - 6 IS - 5 SP - 755 EP - 758 ER - TY - JOUR A1 - Riedl, Katharina A. A1 - Kampf, Thomas A1 - Herold, Volker A1 - Behr, Volker C. A1 - Bauer, Wolfgang R. T1 - Wall shear stress analysis using 17.6 Tesla MRI: A longitudinal study in ApoE\(^{-/-}\)mice with histological analysis JF - PLoS One N2 - This longitudinal study was performed to evaluate the feasibility of detecting the interaction between wall shear stress (WSS) and plaque development. 20 ApoE\(^{-/-}\)mice were separated in 12 mice with Western Diet and 8 mice with Chow Diet. Magnetic resonance (MR) scans at 17.6 Tesla and histological analysis were performed after one week, eight and twelve weeks. Allin vivoMR measurements were acquired using a flow sensitive phase contrast method for determining vectorial flow. Histological sections were stained with Hematoxylin and Eosin, Elastica van Gieson and CD68 staining. Data analysis was performed using Ensight and a Matlab-based "Flow Tool". The body weight of ApoE\(^{-/-}\)mice increased significantly over 12 weeks. WSS values increased in the Western Diet group over the time period; in contrast, in the Chow Diet group the values decreased from the first to the second measurement point. Western Diet mice showed small plaque formations with elastin fragmentations after 8 weeks and big plaque formations after 12 weeks; Chow Diet mice showed a few elastin fragmentations after 8 weeks and small plaque formations after 12 weeks. Favored by high-fat diet, plaque formation results in higher values of WSS. With wall shear stress being a known predictor for atherosclerotic plaque development, ultra highfield MRI can serve as a tool for studying the causes and beginnings of atherosclerosis. KW - phase-contrast MRI KW - flow patterns KW - blood flow KW - apolipoprotein-E KW - atheriosclerosis KW - mouse KW - mice KW - quantification KW - association KW - lesions Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-229318 VL - 15 IS - 8 ER - TY - JOUR A1 - Kurz, Felix T. A1 - Kampf, Thomas A1 - Buschle, Lukas R. A1 - Schlemmer, Heinz-Peter A1 - Bendszus, Martin A1 - Heiland, Sabine A1 - Ziener, Christian H. T1 - Generalized moment analysis of magnetic field correlations for accumulations of spherical and cylindrical magnetic perturbers JF - Frontiers in Physics N2 - In biological tissue, an accumulation of similarly shaped objects with a susceptibility difference to the surrounding tissue generates a local distortion of the external magnetic field in magnetic resonance imaging. It induces stochastic field fluctuations that characteristically influence proton spin dephasing in the vicinity of these magnetic perturbers. The magnetic field correlation that is associated with such local magnetic field inhomogeneities can be expressed in the form of a dynamic frequency autocorrelation function that is related to the time evolution of the measured magnetization. Here, an eigenfunction expansion for two simple magnetic perturber shapes, that of spheres and cylinders, is considered for restricted spin diffusion in a simple model geometry. Then, the concept of generalized moment analysis, an approximation technique that is applied in the study of (non-)reactive processes that involve Brownian motion, allows deriving analytical expressions of the correlation function for different exponential decay forms. Results for the biexponential decay for both spherical and cylindrical magnetized objects are derived and compared with the frequently used (less accurate) monoexponential decay forms. They are in asymptotic agreement with the numerically exact value of the correlation function for long and short times. KW - magnetized sphere/cylinder KW - magnetic susceptibility KW - correlation function KW - diffusion KW - magnetic resonance imaging Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-190604 SN - 2296-424X VL - 4 ER - TY - JOUR A1 - Herold, Volker A1 - Kampf, Thomas A1 - Jakob, Peter Michael T1 - Dynamic magnetic resonance scattering JF - Communications Physics N2 - Dynamic light scattering is a popular technique to determine the size distribution of small particles in the sub micrometer region. It operates in reciprocal space, by analyzing the signal fluctuations with the photon auto correlation function. Equally, pulsed field gradient magnetic resonance is a technique generating data in the reciprocal space of the density distribution of an object. Here we show the feasibility of employing a magnetic resonance imaging system as a dynamic scattering device similar to dynamic light scattering appliances. By acquiring a time series of single data points from reciprocal space, analogue to dynamic light scattering, we demonstrate the examination of motion patterns of microscopic particles. This method allows the examination of particle dynamics significantly below the spatial resolution of magnetic resonance imaging. It is not limited by relaxation times and covers a wide field of applications for particle or cell motion in opaque media. KW - Characterization and analytical techniques KW - Imaging techniques Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-201091 VL - 2 ER - TY - JOUR A1 - Winter, Patrick A1 - Andelovic, Kristina A1 - Kampf, Thomas A1 - Gutjahr, Fabian Tobias A1 - Heidenreich, Julius A1 - Zernecke, Alma A1 - Bauer, Wolfgang Rudolf A1 - Jakob, Peter Michael A1 - Herold, Volker T1 - Fast self-navigated wall shear stress measurements in the murine aortic archusing radial 4D-phase contrast cardiovascular magnetic resonance at 17.6 T JF - Journal of Cardiovascular Magnetic Resonance N2 - Purpose 4D flow cardiovascular magnetic resonance (CMR) and the assessment of wall shear stress (WSS) are non-invasive tools to study cardiovascular risks in vivo. Major limitations of conventional triggered methods are the long measurement times needed for high-resolution data sets and the necessity of stable electrocardiographic (ECG) triggering. In this work an ECG-free retrospectively synchronized method is presented that enables accelerated high-resolution measurements of 4D flow and WSS in the aortic arch of mice. Methods 4D flow and WSS were measured in the aortic arch of 12-week-old wildtype C57BL/6 J mice (n = 7) with a radial 4D-phase-contrast (PC)-CMR sequence, which was validated in a flow phantom. Cardiac and respiratory motion signals were extracted from the radial CMR signal and were used for the reconstruction of 4D-flow data. Rigid motion correction and a first order B0 correction was used to improve the robustness of magnitude and velocity data. The aortic lumen was segmented semi-automatically. Temporally averaged and time-resolved WSS and oscillatory shear index (OSI) were calculated from the spatial velocity gradients at the lumen surface at 14 locations along the aortic arch. Reproducibility was tested in 3 animals and the influence of subsampling was investigated. Results Volume flow, cross-sectional areas, WSS and the OSI were determined in a measurement time of only 32 min. Longitudinal and circumferential WSS and radial stress were assessed at 14 analysis planes along the aortic arch. The average longitudinal, circumferential and radial stress values were 1.52 ± 0.29 N/m2, 0.28 ± 0.24 N/m2 and − 0.21 ± 0.19 N/m2, respectively. Good reproducibility of WSS values was observed. Conclusion This work presents a robust measurement of 4D flow and WSS in mice without the need of ECG trigger signals. The retrospective approach provides fast flow quantification within 35 min and a flexible reconstruction framework. KW - 4D flow KW - WSS KW - OSI KW - Self-navigation KW - Mouse KW - Aortic arch Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-201120 VL - 21 ER - TY - THES A1 - Kampf, Thomas T1 - Quantifizierung myokardialer Mikrostruktur und Perfusion mittels longitudinaler NMR Relaxation T1 - Quantification of myocardial micro structure and perfusion exploiting longitudinal NRM relaxation times N2 - Ziel der Arbeit war es die Quantifizierung funktioneller bzw. mikrostruktureller Parameter des Herzmuskels mit Hilfe T1-basierter Methoden zu verbessern. Diese Methoden basieren darauf, die gewünschte Information durch eine geeignete Präparation der Magnetisierung bzw. durch die Gabe von Kontrastmittel in den Zeitverlauf der longitudinalen Relaxation zu kodieren. Aus der Änderung der Relaxationszeit läßt sich dann die gewünschte Information bestimmen. Dafür sollte sowohl der Einfluß der Anatomie als auch derjenige der Meßmethodik auf die Bestimmung der longitudinalen Relaxationszeit und damit auf die Quantifizierung der Funktion bzw. Mikrostrukturparameter untersucht werden. Speziell der Einfluß der Bildgebungssequenz führt dazu, daß nur eine scheinbare Relaxationszeit gemessen wird. Während dies keinen Einfluß auf die T1-basierte Bestimmung der untersuchten Mikrostrukturparameter hatte, ergab sich für die Perfusionsquantifizierung eine deutliche Abhängigkeit von den Parametern der verwendeten IRLL-Sequenz. Um diesen Einfluß gerecht zu werden, wurden an die Meßmethodik angepaßte Gleichungen zur Bestimmung der Perfusion gefunden mit denen die systematischen Abweichungen korrigiert werden können. Zusätzlich reduzieren die angepaßten Gleichungen die Anforderungen bezüglich der Inversionsqualität im schichtselektiven Experiment. Dies wurde in einem weiteren Projekt bei der Bestimmung der Nierenperfusion im Mausmodell ausgenutzt. Neben der Untersuchung der Auswirkungen der Meßmethode wurde auch der Einfluß der anatomischen Besonderheiten des Blutkreislaufs am Herzen auf die Parameterquantifizierung mittels T1-basierter Methoden untersucht. Es konnte gezeigt werden, daß auf Grund der Anatomie des Herzens bei typischen Orientierungen der Bildgebungsschicht, auch bei der schichtselektiven Inversionspräparation der Magnetisierung des Herzmuskels ein Anteil des Blutpools invertiert wird. Daraus folgt, daß die vereinfachende Annahme, nach welcher bei schichtselektiver Präparation in Folge von Perfusion nur Blut mit Gleichgewichtsmagnetisierung den Herzmuskel erreicht, nicht erfüllt ist. Es konnte gezeigt werden, daß dies bei Perfusion zu einer deutlichen Unterschätzung der berechneten Perfusionswertes führt. Um mit diesem Problem umgehen zu können, wurde aufbauend auf einem vereinfachten Modell der zeitlichen Entwicklung der Blutmagnetisierung eine Korrektur für die Bestimmung der Perfusionswerte gefunden welche den Einfluß der anatomischen Besonderheiten berücksichtigt. Das für die Perfusionskorrektur eingeführte Model prognostiziert ebenso, daß auch bei schichtselektiver Inversion die T1-basierte Bestimmung der untersuchten Mikrostrukturparameter von der Perfusion abhängig wird und eine systematische Überschätzung der quantifizierten Werte verursacht. Da die Perfusion im Kleintier deutlich höher ist als im Menschen, ist dieser Einfluß besonders in der präklinischen Forschung zu beachten. So können dort allein durch verminderte Perfusion deutliche Änderungen in den bestimmten Werten der Mikrostrukturparameter erzeugt werden, welche zu einer fehlerhaften Interpretation der Ergebnisse führen und somit ein falsches Bild für die Vorgänge im Herzmuskel suggerieren. Dabei bestätigt der Vergleich mit experimentellen Ergebnissen aus der Literatur die Vorhersagen für das Rattenmodell. Beim Menschen ist der prognostizierte Effekt deutlich kleiner. Der prognostizierte Fehler bspw. im RBV-Wert liegt in diesem Fall bei etwa 10% und wird üblicherweise in der aktuellen Forschung vernachlässigt. Inwieweit dies in er klinischen Forschung gerechtfertigt ist, muß in weiteren Untersuchungen geklärt werden. Den untersuchten Methoden zur Bestimmung von funktionellen und mikrostrukturellen Parametern ist gemein, daß sie eine exakte Quantifizierung der longitudinalen Relaxationszeit T1 benötigen. Dabei ist im Kleintierbereich die klassische IRLL-Methode als zuverlässige Sequenz zur T1-Quantifizierung etabliert. In der klinischen Bildgebung werden auf Grund der unterschiedlichen Zeitskalen und anderer technischer Voraussetzungen andere Anforderungen an die Datenakquisition gestellt. Dabei hat in den letzten Jahren die MOLLI-Sequenz große Verbreitung gefunden. Sie ist eine Abwandlung der IRLL-Sequenz, bei der mit einer bSSFP-Bildgebungssequenz getriggert ganze Bilder während eines Herzschlages aufgenommen werden. Die MOLLI-Sequenz reagiert dabei empfindlich auf die Wartezeiten zwischen den einzelnen Transienten. Um mit diese Problematik in den Griff zu bekommen und gleichzeitig die Meßzeit verkürzen zu können wurde eine neue Methode zum Fitten der Daten entwickelt, welche die Abhängigkeit der scheinbaren Relaxationszeit von der Wartezeit zwischen den einzelnen Transienten, sowie der mittleren Herzrate fast vollständig eliminiert. Diese Methode liefert für das ganze klinisch Spektrum an erwarteten T1-Zeiten, vor und nach Kontrastmittelgabe, stabile Ergebnisse und erlaubte ein deutliche Verkürzung der Meßzeit, ohne die Anzahl der aufgenommenen Meßzeitpunkte zu reduzieren. Dies wurde in einer initialen klinischen Studie genutzt, um ECV-Werte in Patienten zu bestimmen. Ein Nachteil der Verwendung der MOLLI-Sequenz ist, daß nur die scheinbare Relaxationszeit aus den Fit der Meßdaten bestimmt wird. Die standardmäßig genutzte Korrektur benutzt aber dem gefitteten Wert der Gleichgewichtsmagnetisierung um den wahren T1-Wert zu bestimmen. Somit ist es für die Bestimmung des T1-Wertes notwendig, die Qualität der Inversionspräparation zu kennen. Auf Basis der neuen Fitmethode wurde eine Anpassung der MOLLI-Sequenz demonstriert, welche die Bestimmung der Gleichgewichtsmagnetisierung unabhängig von der Qualität der Inversionspräparation erlaubt. Dafür verlängert sich die Meßdauer lediglich um einen Herzschlag um in geeigneter Weise ein zusätzliches Bild aufnehmen zu können. Abschließend wurde in dieser Arbeit der Signal-Zeit-Verlauf der MOLLI-Sequenz eingehend theoretische untersucht um ein besseres Verständnis der getriggerten IRLL-Sequenzen zu entwickeln. In diesem Zusammenhang konnte eine einfache Interpretation der scheinbaren Relaxationszeit gefunden werden. Ebenso konnte erklärt werden, warum die für ungetriggerte IRLL-Sequenzen abgeleitete Korrekturgleichung auch im getriggerten Fall erstaunlich gute Ergebnisse liefert. Weiterhin konnten Fehlerquellen für die verbleibenden Abweichungen identifiziert werden, welche als Ausgangspunkt für die Ableitung verbesserter Korrekturgleichungen genutzt werden können. N2 - The goal of this work was to improve T1-based methods for quantification of functional and microstructural parameters of the heart muscle. These methods encode the desired information in the longitudinal relaxation by a dedicated magnetization preparation or by due to the administration of contrast agents. Hence, the alteration of the longitudinal relaxation time can be used to determine the desired information. To accurately quantify these parameters, the influence of the anatomy as well as the data acquisition on the longitudinal relaxation time and hence the quantification of the functional and micro structural parameters is investigated. It is known, that the choice of imaging sequence may influence the recovery of the magnetization and only an apparent relaxation time can be measured. While this had no effect on the T1-based quantification of the investigated microstructural parameters, the calculated perfusion value showed a strong dependence on the parameters of the used IRLL sequence. To take the influence of the imaging sequence into account, adapted equations for perfusion quantification were found. Hence, it was possible to correct for the systematic deviation by the IRLL sequence. Additionally, it could be shown that these adapted equations relax some of the requirements on the slice selective inversion experiment which could be utilized in the quantification of renal perfusion in a mouse model. Beside the influence of the imaging sequence also the influence of cardiovascular anatomy of the heart on the T1-based quantification methods was investigated. It was shown that for typical orientations of the imaging slice, also for the slice selective preparation a part of the blood pool magnetization is inverted. This violates the assumption that in the slice selective case only magnetization in equilibrium state enters the heart muscle and leads to a drastic underestimation of the quantified perfusion value. Based on a simplified model of the evolution of the blood magnetization the effects of the partial blood pool inversion were derived for perfusion quantification. The same simplified model was used, to investigate the influence of the imperfect slice selective inversion preparation in the T1-based quantification of the investigated micro structural parameters. It was shown, that the inflow of partially inverted blood into the capillary bed results in a perfusion dependent overestimation of the investigated microstructural parameters. As perfusion in small mammals is higher than in humans, the resulting bias has to be considered particularly in pre-clinical studies. In these animal models a reduced perfusion can result in a strong variation of the microstructural parameters which could be misinterpreted and hence may lead to a wrong understanding of the processes in the heart muscle. The predicted bias was compared with residual errors in the literature neglecting the partial inversion and found a good agreement in a rat model. For humans the expected bias is much smaller due to the lower perfusion values. The predicted bias for the RBV value is approximately 10% and hence, the effect is neglected in the current literature. However, if this justified must be investigated in further studies. All investigated methods for parameter quantification require the exact knowledge of the longitudinal relaxation time T1. For small animals the usual choice is an IRLL sequence, which have been established and demonstrated to be reliable and robust. Due to the different timescales and other technical aspects, however, the requirements in clinical imaging are different for data acquisition. In recent years the MOLLI sequence has become popular for T1 quantification. The MOLLI sequence is modification of IRLL sequence with a single shot bSSFP imaging module triggered usually to the end diastolic heart phase. However, the MOLLI sequence shows a strong dependence on the waiting times between the inversion prepared transients. To overcome this problem and provide a robust quantification of the apparent relaxation time with reduced the overall measurement time a new fitting procedure was developed. Thus, it was able to almost completely eliminate the dependence on the waiting time between the transients as well as the mean heart rate. The new method provided robust quantification over the complete range of clinical relevant longitudinal relaxation times (pre and post administration of contrast agents). Additionally, it was possible to reduce the measurement time without reducing the number of acquired data. This method was used in a pilot study to measure ECV in patients. A disadvantage of the MOLLI sequence is that in only provides an apparent relaxation time from the data fit and a correction for the real relaxation time is necessary. To calculate $T_1$, the common correction requires the knowledge of the equilibrium as well as the steady state magnetization. Hence, the quality of the inversion preparation is important and must be determined. Exploiting the properties of the new fitting method an adaption of the MOLLI sequence was proposed which allows the measurement of the equilibrium magnetization independent from quality of the inversion preparation by extending the measurement time for only a single heart beat to acquire a single additional image before the first inversion preparation. The final part of this work was dedicated improve the understanding of triggered IRLL sequences as the MOLLI. Hence, the signal evolution of these triggered sequences was investigated theoretically. Hence, a simple interpretation of the apparent relaxation time could be found from the results. Furthermore, a better understanding was reached for the surprisingly good results of the commonly used correction which was derived from the untriggered continuous case. Additionally, sources of the remaining deviations were identified and can be used for subsequent investigations to find better correction equations which allow for a more accurate quantification of T1. KW - Kernspintomographie KW - Relaxationszeit KW - Perfusion KW - Spin-Gitter-Relaxation KW - T1 Relaxation KW - Herzbildgebung KW - MRT KW - MOLLI KW - Inversion Recovery Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-174261 ER -