Measuring Venous Structure and Oxygenation with Variable-Refocusing-Interval Magnetic Resonance Imaging

• Applicant: Dr. Thies H. Jochimsen
• Subject Area: Nuclear Medicine, Radiotherapy, Radiobiology
• Term: from 2006 to 2008
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 29509068

Measuring the microstructure and oxygenation of the venous vasculature is an interesting approach for a better understanding of the blood oxygenation level dependent contrast, the early detection of stroke (disordered oxygenation) and the identification of tumor (abnormal vessel structure). In this proposal, a novel approach is put forward, which exploits the fact that, in the presence of microscopic magnetic heterogeneity caused by deoxygenated hemoglobin, the measured transverse relaxation rate of water diffusing in these inhomogeneities depends on the refocusing interval in a Carr-Purcell-Meiboom-Gill sequence. Thus, it is anticipated that the exact shape of this dependency yields valuable information about the venous microstructure and oxygenation. The implementation of the technique becomes possible by a novel correction scheme for radio-frequency field inhomogeneities. In addition, it is suggested to separate intra- and extravascular effects by the use of flow weighting and to perform the experiments at different field strengths to gain insight into the exact mechanism that causes the refocusing-interval dependency. By developing a model which relates the dependency to a certain vessel size and oxygenation, it will be possible to generate maps of these properties.

• DFG Programme: Research Grants