RUPRECHT-KARLS- UNIVERSITY HEIDELBERG Computer Assisted Clinical Medicine Prof. Dr. Lothar Schad Master‘s Program in Medical Physics 11/26/2020 | Page 1 Physics of Imaging Systems Basic Principles of Magnetic Resonance Imaging III Prof. Dr. Lothar Schad Chair in Computer Assisted Clinical Medicine Faculty of Medicine Mannheim University of Heidelberg Theodor-Kutzer-Ufer 1-3 D-68167 Mannheim, Germany
[email protected] www.ma.uni-heidelberg.de/inst/cbtm/ckm/ RUPRECHT-KARLS- UNIVERSITY HEIDELBERG Computer Assisted Clinical Medicine Prof. Dr. Lothar Schad Relaxation 11/26/2020 | Page 2 Relaxation Seite 1 1 RUPRECHT-KARLS- UNIVERSITY HEIDELBERG Computer Assisted Clinical Medicine Prof. Dr. Lothar Schad Magnetization: M and M 11/26/2020 | Page 3 z xy longitudinal magnetization: Mz transversal magnetization: Mxy transversal magnetization: Mxy - phase synchronization after a 90°-pulse - the magnetic moments of the probe start to precede around B1 leading to a synchronization of spin packages → Mxy - after 90°-pulse Mxy = M0 RUPRECHT-KARLS- UNIVERSITY HEIDELBERG Computer Assisted Clinical Medicine Prof. Dr. Lothar Schad Movie: M and M 11/26/2020 | Page 4 z xy source: Schlegel and Mahr. “3D Conformal Radiation Therapy: A Multimedia Introduction to Methods and Techniques" 2007 Seite 2 2 RUPRECHT-KARLS- UNIVERSITY HEIDELBERG Computer Assisted Clinical Medicine Prof. Dr. Lothar Schad Longitudinal Relaxation Time: T1 11/26/2020 | Page 5 thermal equilibrium excited state after 90°-pulse: -N-1/2 = N+1/2 and Mz = 0, Mxy = M0 after RF switched off: - magnetization turns back to thermal equilibrium - Mz = M0, Mxy = 0 → T1 relaxation longitudinal relaxation time T1 spin-lattice-relaxation time T1 RUPRECHT-KARLS- UNIVERSITY HEIDELBERG Computer Assisted Clinical Medicine Prof.