Nuclear Magnetic Resonance-Bushberg Chapter 14 Diagnostic Radiology Imaging Physics Course Magnetism and the Magnetic Properties of Matter Magnetism and the Magnetic Properties of Matter Magnetic fields arise from magnetic dipoles(N/S) N-side the origin of magnetic field lines(arbitrary) Attraction (N-S)and repulsion (N-N S-S) Magnetic field strength (flux density):B Measured in tesla (T)and gauss (G):1=10.000 Earth magnetic field -1/20,000 T or 0.5 G Magnetic fields arise from Permanent magnets Current through a wire or solenoid(current amplitude sets B magnitude) 8Ts4n Magnetic Characteristics of the Nucleus Nuclear Magnetic Characteristics of the Elements Magnetic moment (u)describes the nuclear B field magnitude Mucena 2持 ◆Pairing of p'-porn-n causesμto cancel out 。So if P(total p")and N (total n)is even-→nonittle u If N even and P odd or P even and N odd-resultantu (NMR eff.) TABLE 14-1.PROPERTIES OF THE NEUTRON AND PROTON Neutron Proton levant clemets hat are canddates for RMR kg 1 股8 Physiologic concentration Isotopic abundance 6所10n 2g*10- Relative sensitvty H (p")provide 104-10 times the signal from 2Na or 3P 0UW and Rn 9.19and26May2005Nuclear Magnetic Resonance – Bushberg Chapter 14 Diagnostic Radiology Imaging Physics Course 9, 19 and 26 May 2005 3 © UW and Brent K. Stewart, PhD, DABMP 9 Magnetism and the Magnetic Properties of Matter Magnetism and the Magnetic Properties of Matter ™ Magnetic fields arise from magnetic dipoles (N/S) Magnetic fields arise from magnetic dipoles (N/S) ™ N – side the origin of magnetic field lines (arbitrary) side the origin of magnetic field lines (arbitrary) ™ Attraction (N-S) and repulsion (N-N & S-S) ™ Magnetic field strength (flux density): B ™ Measured in tesla (T) and gauss (G): 1 T = 10,000 G ™ Earth magnetic field ~ 1/20,000 T or 0.5 G ™ Magnetic fields arise from ™ Permanent magnets ™ Current through a wire or solenoid (current amplitude sets B Current through a wire or solenoid (current amplitude sets B magnitude) magnitude) © UW and Brent K. Stewart, PhD, DABMP 10 Magnetism and the Magnetic Properties of Matter Magnetism and the Magnetic Properties of Matter c.f. Bushberg, et al. The Essential Physics of Medical Imaging, 2nd ed., p. 374 and 377. © UW and Brent K. Stewart, PhD, DABMP 11 Magnetic Characteristics of the Nucleus Magnetic Characteristics of the Nucleus ™ Magnetic properties of nuclei determined by the spin and charge Magnetic properties of nuclei determined by the spin and charge distribution (quarks) of the nucleons (p+ and n) ™ Magnetic moment ( Magnetic moment (µ) describes the nuclear B field magnitude ™ Pairing of p+-p+ or n-n causes n causes µ to cancel out to cancel out ™ So if P (total p+) and N (total n) is even ) and N (total n) is even → no/little no/little µ ™ If N even and P odd or P even and N odd If N even and P odd or P even and N odd → resultant resultant µ (NMR eff.) c.f. Bushberg, et al. The Essential Physics of Medical Imaging, 2nd ed., p. 375. © UW and Brent K. Stewart, PhD, DABMP 12 Nuclear Magnetic Characteristics of the Elements Nuclear Magnetic Characteristics of the Elements ™ Biologically relevant elements that are candidates for NMR/MRI Biologically relevant elements that are candidates for NMR/MRI ™ Magnitude of Magnitude of µ ™ Physiologic concentration ™ Isotopic abundance ™ Relative sensitivity ™ 1H (p+) provide 104-106 times the signal from times the signal from 23Na or 31P c.f. Bushberg, et al. The Essential Physics of Medical Imaging, 2nd ed., p. 376