FU Berlin Digitale Dissertation
Claudia Diekmann : MR-Perfusion measurements in experimental gliomas MR-Perfusionsmessungen an experimentellen Hirntumoren
|Abstract| |Table of Contents| |More Information|

Abstract Gliomas are accompanied by angiogenesis (new vessel growth), a process essential for their progression from low-grade to high-grade, and there is a clear correlation between increased vascularity and increased malignancy. Quantitative tumor microvascular permeability assays generated with macromolecular magnetic resonance imaging (MRI) contrast agents correlate closely with histologic tumor grades (1). We performed an animal study to evaluate a model for the quantitative mapping of vascular, interstitial, and cellular volume and blood vessel permeability. Advantages of an animal model are the possibility to use experimental contrast agents of various molecular sizes and to compare MRI data with histologic findings. 9L glioma cell lines were stereotactically implanted into the left hemisphere of female Fisher 344 rat brains. MR imaging was performed two weeks after inocculation. For the examination, rats were anesthetized with 2:1 ketamine-rompun adjusted for body weight and placed in the center of the bore. MRI experiments were performed at 2.4 T using a Bruker Biospec MSL-X11 system equipped with actively shielded gradient coils. A 6 cm diameter resonator was used for RF excitation and signal reception. Tumors were localized with T2-weighted images. After 10 seconds of baseline acquisition, a bolus injection of three different contrast agents (DDM 128 (SPIO: super- paramagnetic iron oxide with gaussian weight distribution), Gadomer-17, Schering, and Magnevist, Schering) was administered into tail the vein of three different groups (N=5). Dynamic contrast changes were measured in a single transverse slice through the tumor using a snapshot FLASH sequence or an Inversion Recovery FLASH sequence depending on the contrast agent. After measurements, rats were perfused with formaline and brains removed for histologic analysis. Quantitative vascular, interstitial, and cellular volume maps and permeability maps were calculated using different pharmacokinetic models depending on the molecular weight of the contrast agent. The pharmacokinetic models explain the time-dependent changes in concentration Ci,x of contrast agent in interstitial volume Vi,x: , where A is the surface of blood vessels, Cp the concentration of contast agent in blood plasma, k the permeability, and x the number of transport mechanisms, which varies for each contrast agent. Furthermore we substituted the surface by a mean vascular radius of blood vessels and were able to split the permeability-surface product. Due to its molecular size and weight distribution, DDM 128 allowed only calculation of qualitative vascular volume maps. With Magnevistâ, vascular and interstitial volume maps but, due to the small size, no permeability maps could be calculated. Gadomer-17â allowed to generate quantitative vascular, interstitial, and cell volume maps and permeability maps and showed a peripherally increased vascular volume.

Table of Contents Download the whole PhDthesis as a zip-tar file or as zip-File For download in PDF format click the chapter title 1 Titel, Inhalt, Zusammenfassung 1 Einleitung 2 Medizinische Einführung 2.1 Angiogenese 3 Die Grundlagen der Kernspinresonanz 3.1 Quantenmechanische Betrachtung des kernmagnetischen Momentes im äußeren Magnetfeld 3.2 Molekulare Wechselwirkungen 3.3 Klassische Betrachtung der Magnetisierung im äußeren Magnetfeld 3.4 Relaxationsprozesse 3.5 NMR-Bildgebung Ortskodierung 30 4 Methoden zum Bolustrack-Verfahren 4.1 Blutflußphysiologie 4.2 Bolustrack-Verfahren 5 Material und Methoden 5.1 Tiermodell 5.2 Tumormodell 5.3 Anästhesie und Medikation 5.4 Kontrastmittel 5.5 NMR-System 5.6 Software 5.7 Sequenzen 5.8 Experimente 6 Ergebnisse 6.1 Phantommessungen. 6.2 Dynamische Messung an experimentellen Hirntumoren unter Verwendung der Kontrastmittel Gd-DTPA und Gadomer-17: Auswertung nach dem Weissleder-Modell 6.3 Dynamische Messung an experimentellen Hirntumoren unter Verwendung des Kontrastmittels DDM 128 6.4 Dynamische Messung an experimentellen Hirntumoren unter Verwendung des Kontrastmittels Gd-DTPA 6.5 Dynamische Messung an experimentellen Hirntumoren unter Verwendung des Kontrastmittels Gadomer-17 6.6 Histologie und Korrelation mit MR-Ergebnissen 89 6.7 Fehlerbetrachtung 7 Diskussion und Zusammenfassung der Ergebnisse 8 Literaturverzeichnis 9 Anhang 9.1 Abkürzungsverzeichnis aus Abb. 5.1 9.2 Auswerteprogramm Variablenliste Liste der Publikationen Danksagung

More Information:
Online available:	http://www.diss.fu-berlin.de/2001/214/indexe.html
Language of PhDThesis:	german
Keywords:	pharmacokinetic magnetic resonance perfusion measurments
DNB-Sachgruppe:	33 Medizin
Date of disputation:	17-Jul-2001
PhDThesis from:	Fachbereich Physik, Freie Universität Berlin
First Referee:	Prof. Dr. rer. nat. Klaus D. Kramer
Second Referee:	Prof. Dr. rer. nat. Herbert Rinneberg
Contact (Author):	cldiekm@yahoo.com
Contact (Advisor):	kramerk@physik.fu-berlin.de
Date created:	11-Nov-2001
Date available:	29-Nov-2001

 

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