Nuclear Magnetic Resonance-Bushberg Chapter 14 Diagnostic Radiology Imaging Physics Course Raphex 2000 Diagnostic Questions Raphex 2003 Diagnostic Questions D42.Which of the following elements would not be of D53.For hydrogen imaging in a 1.0 T MRI unit,the interest in an MRI image? frequency of the RF signal is about: Element 2 A ◆A.Hydrogen 1 1 ◆A.400kHz ◆B.Carbon 6 13 ◆B.4MHz ◆C.Oxygen 16 ◆C.40MHz ◆D.Sodium 11 23 ◆D.400MHz ◆E.Phosphorus 15 31 ◆E.4GHz 17 Geometric Orientation Resonance and Excitation Two frames of reference used Return to equilibrium results in RF emission from u with Amplitude proportional the number of excited nuclei(spin p) Rate depends on the characteristics of the sample(T1 and T2) Rotating frame-angular Excitation,detection analysis the basics for NMR/MRI Resonance occurs when applied RF magnetic field(B) is precisely matched in frequency to that of the nuclei explaining various interactions ◆Absorption of RF energy promotes low-Eμ→high-Eμ M:transverse magnetization Amplitude and duration of RF pulse determines the LB.(at equilibrium=0) number of nuclei that undergo the energy transition(0) Whe Continued RF application induces a retum to equilibrium ap UW and Rr 9.19and26May2005 JNuclear Magnetic Resonance – Bushberg Chapter 14 Diagnostic Radiology Imaging Physics Course 9, 19 and 26 May 2005 5 © UW and Brent K. Stewart, PhD, DABMP 17 Raphex 2000 Diagnostic Questions Raphex 2000 Diagnostic Questions ™ D42. Which of the following elements would not be of . Which of the following elements would not be of interest in an MRI image? Element Element Z A ™ A. Hydrogen 1 1 ™ B. Carbon 6 13 ™ C. Oxygen 8 16 ™ D. Sodium 11 23 ™ E. Phosphorus 15 31 © UW and Brent K. Stewart, PhD, DABMP 18 Raphex 2003 Diagnostic Questions Raphex 2003 Diagnostic Questions ™ D53. For hydrogen imaging in a 1.0 T MRI unit, the . For hydrogen imaging in a 1.0 T MRI unit, the frequency of the RF signal is about: frequency of the RF signal is about: ™ A. 400 kHz ™ B. 4 MHz ™ C. 40 MHz ™ D. 400 MHz ™ E. 4 GHz © UW and Brent K. Stewart, PhD, DABMP 19 Geometric Orientation ™ Two frames of reference used ™ Laboratory frame – stationary stationary reference from observer’s reference from observer’s POV ™ Rotating frame – angular angular frequency equal to the Larmor frequency equal to the Larmor precessional frequency ™ Both frames are useful in Both frames are useful in explaining various interactions ™ Mxy: transverse magnetization, : transverse magnetization, ⊥ B0 (at equilibrium = 0) (at equilibrium = 0) ™ When RF applied, Mz tipped into the x-y (transverse) plane c.f. Bushberg, et al. The Essential Physics of Medical Imaging, 2nd ed., pp. 380-381. Rotating Frame Lab Frame Rotating Frame © UW and Brent K. Stewart, PhD, DABMP 20 Resonance and Excitation ™ Return to equilibrium results in RF emission from Return to equilibrium results in RF emission from µ with ™ Amplitude proportional the number of excited nuclei (spin Amplitude proportional the number of excited nuclei (spin ρ) ™ Rate depends on the characteristics of the sample (T1 and T2) Rate depends on the characteristics of the sample (T1 and T2) ™ Excitation, detection & analysis the basics for NMR/MRI Excitation, detection & analysis the basics for NMR/MRI ™ Resonance occurs when applied RF magnetic field (B1) is precisely matched in frequency to that of the nuclei is precisely matched in frequency to that of the nuclei ™ Absorption of RF energy promotes low-E µ → high-E µ ™ Amplitude and duration of RF pulse determines the Amplitude and duration of RF pulse determines the number of nuclei that undergo the energy transition ( number of nuclei that undergo the energy transition (θ) ™ Continued RF application induces a return to equilibrium