Marco Dominietto
(Institute for Biomedical Engineering - ETH and University Zurich)
Several imaging techniques are available to study the neovasculature during tumor angiogenesis. MRI provides information on morphology,blood volume (TBV),blood flow (TBF) and on the average vessel diameter (vessel size index,VSI),PET enables studies of metabolic activity. To visualize the 3D vessel architecture at a capillary level (5-10μm) SRμCT is needed.Validation of in vivo imaging data is achieved by comparison with histology.
The aim of this work was to characterize vessel formation in tumors using multimodal imaging strategies in order to elucidate multiple aspects of the angiogenic process.
Twelve balb/c nude mice were injected s.c. with 106 C51 cells (colon carcinoma). For a first validation study, anatomical images,TBV,TBF,VSI maps of 6 mice were recorded using MRI.The animals were sacrificed and the tumors explanted for SRμCT in phase-contrast and absorption modes.
Thereafter a longitudinal MRI-PET study has been carried out using 6 mice. Measurements were performed every 3 days.PET protocol consists of the injection of 18F-MISO to visualize the hypoxic regions. Histological examination was performed on every tumor using the endothelial marker CD31,hypoxic marker pimonidazole and perfusion reporter Hoechst. The data were analyzed using the standard medical images approach and a novel method based on fractal analysis.
The results display significant tissue heterogeneity in the growing tumor. Differences have been found with regard to morphological appearance, physiological behavior and degree of hypoxia. Images from SRμCT showed a chaotic structure of the vessel architecture.
By using complementary imaging modalities it is possible to analyze various aspects of the vessel network formation in tumor tissue yielding interesting mechanistic insight.
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Marco Dominietto is a medical physicist who has been working since 2008 as PhD student at the Institute for Biomedical Engineering (ETH and University of Zurich, Switzerland). From 2005 to 2007 he worked at the TERA Foundation (c/o CERN, Geneva, Switzerland) and from 2000 to 2005 at Novara Hospital (Novara, Italy).
During his experience in the clinical environment he got the expertise in conventional radiotherapy, nuclear medicine and medical imaging. Additionally he contributed to research about physical aspects of patient treatment and radiation protection.
He decided then to move to research starting his collaboration at the proton therapy project of TERA Foundation. The first project was the study of the medical uses of radioisotopes produced by a 30 MeV cyclotron. Afterwards he collaborated at the development of a 3D dose calculation code for proton pencil beam irradiation in radiotherapy treatment.
The PhD project he has started is in the area of basic animal research. The goal of such project is to set up new imaging modalities and use them to study the angiogenesis in tumor mice models. The first results have been presented at the World Molecular Imaging Congress (2008, 2009). Actually he is working on a novel model to analyze medical imaging data using fractal analysis methods.
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Marco Dominietto
(Institute for Biomedical Engineering - ETH and University Zurich)
Bert Müller
(Biomaterials Science Center, University of Basel)
Markus Rudin
(Institute for Biomedical Engineering - ETH and University Zurich)
Ruth Keist
(Institute for Biomedical Engineering - ETH and University Zurich)
Sabrina Lang
(Biomaterials Science Center, University of Basel)
Steffi Lehmann
(Institute for Biomedical Engineering - ETH and University Zurich)
