MEDRADSC 2Z03 Lecture Notes - Lecture 4: Rotating Magnetic Field, Larmor Precession, Spin Echo

• School: McMaster University
• Department: Medical Radiation Sciences
• Course: MEDRADSC 2Z03
• Professor: Dawn Danko

Document Summary

Demonstrate a basic understanding of the principles of mr: Identify the primary indications for mr imaging in diagnostics. Identify various mr weighting sequences and relate to images. Discuss the uses of contrast in mr. If an electromagnetic radiofrequency (rf) pulse is applied at the larmor frequency, then the proton can absorb that energy. A proton jumps to a higher e state. What happens when the transmitter turns off: rf energy is retransmitted from the rotating transverse magnetic vector (a rotating magnetic field produces rf waves) At the resonant frequency (listen to the right station!) Signal is proportional to proton density: nmv begins to recover in the longitudinal plane (exponential) =longitudinal or spin-lattice(t1) relaxation: spins begin to dephase (exponential) T1 is a time constant that is unique to every tissue this is how we can differentiate between different tissues. T1 is impacted by magnetic field strength.