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Perfusionsbildgebung anhand positiver und negativer Bolusanwendung in der Magnetpartikelbildgebung
Citation Link: https://doi.org/10.15480/882.5075
Publikationstyp
Master Thesis
Date Issued
2022-07-01
Sprache
German
Author(s)
Advisor
Referee
Title Granting Institution
Technische Universität Hamburg
Place of Title Granting Institution
Hamburg
Examination Date
2022-07-25
Institut
TORE-DOI
Citation
Technische Universität Hamburg (2022)
Real-time perfusion imaging is a potential application of magnetic particle imaging. It is used to assess the vascular system and the perfusion of organs and tissues. The intravenous injection of a tracer bolus causes concentration-time curves in a volume of interest. Based on this, various perfusion parameters can be assessed and visualized in perfusion maps, e.g. time to peak, mean transit time, blood volume and blood flow.
At certain diseases the consistent monitoring of the perfusion of certain organs is required. Until the reach of a steady state (when the concentration-time curves do not show a profile anymore), the injected particles spread in the patient’s blood. Thus, the injection of another bolus is necessary for every image acquisition. The maximum amount of tracer that may be injected to a patient in a certain time frame is limited. Additionally, the concentration of the tracer in the blood is increased by every bolus. Though, the change of concentration might not be detectable anymore.
In this work a possible approach to this problem is considered. Therein, the form of the injection for the acquisition of a new perfusion image is inverted by the use of a water or NaCl bolus (negative bolus) instead of a tracer bolus (positive bolus). On the basis of a phantom of a rat’s heart that is connected to a pump, it is investigated if negative boluses might also be used for perfusion imaging as positive boluses to obtain the same results for the calculation of perfusion parameters. The concentration-time curves of the negative boluses necessarily need to be normalized to the positive ones. For this study, optical experiments were performed by use of ink and water as well as MPI measurements by use of tracer and water for the positive and negative boluses, respectively. Based on these experiments, time-curves were derived and assessed concerning their possibility of normalization. Besides, perfusion maps were calculated and compared quantitatively. As can be seen from the experiments, positive and negative boluses of identic size can be normalized to each other.
At certain diseases the consistent monitoring of the perfusion of certain organs is required. Until the reach of a steady state (when the concentration-time curves do not show a profile anymore), the injected particles spread in the patient’s blood. Thus, the injection of another bolus is necessary for every image acquisition. The maximum amount of tracer that may be injected to a patient in a certain time frame is limited. Additionally, the concentration of the tracer in the blood is increased by every bolus. Though, the change of concentration might not be detectable anymore.
In this work a possible approach to this problem is considered. Therein, the form of the injection for the acquisition of a new perfusion image is inverted by the use of a water or NaCl bolus (negative bolus) instead of a tracer bolus (positive bolus). On the basis of a phantom of a rat’s heart that is connected to a pump, it is investigated if negative boluses might also be used for perfusion imaging as positive boluses to obtain the same results for the calculation of perfusion parameters. The concentration-time curves of the negative boluses necessarily need to be normalized to the positive ones. For this study, optical experiments were performed by use of ink and water as well as MPI measurements by use of tracer and water for the positive and negative boluses, respectively. Based on these experiments, time-curves were derived and assessed concerning their possibility of normalization. Besides, perfusion maps were calculated and compared quantitatively. As can be seen from the experiments, positive and negative boluses of identic size can be normalized to each other.
Subjects
Magnetic Particle Imaging
MPI
Perfusionsbildgebung
DDC Class
610: Medizin
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Perfusionsbildgebung anhand positiver und negativer Bolusanwendung in der Magnetpartikelbildgebung.pdf
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