MRI in practice book CHAPTER 1 Real Exam Questions With 100% Correct Verified Answers.

two or more atoms arranged together - correct answer Molecules the most abundant atom in the body - correct answer hydrogen atomic number - correct answer the sum of the protons in the nucleus mass number - correct answer the sum of protons and neutrons in the nucleus isotopes - correct answer atoms of elements with the same number of protons but different number of neutrons Heisenberg's Uncertainty principle - correct answer The position of an electron in the cloud is not predictable as it depends on the energy of an individual electron at any moment in time IONS - correct answer a deficit of the number of electrons compared with protons and causes electrical instability. MR Active Nuclei - correct answer a nuclei with odd mass numbers. spin directions are not equal and opposite, so the nucleus itself has a net spin or Angular momentum Law of electromagnetic induction refers to what 3 forces - correct answer Motion, Magnetism, charge What does the law of electromagnetic induction state - correct answer that if two of these are present, the third it automatically induced Mass number of Hydrogen - correct answer 1 Mass number of Carbon - correct answer 13 Mass number of nitrogen - correct answer 15 Mass number of oxygen - correct answer 17 Mass number of fluorine - correct answer 19 Mass number of sodium - correct answer 23 Mass number of phosphorus - correct answer 31 Protium - correct answer The isotope of the hydrogen nucleus who invented Quantum Theory - correct answer Max Planck 1900 Quanta - correct answer discrete quantities of energy Low energy nuclei - correct answer align their magnetic moments parallel to the external field High energy nuclei - correct answer align their magnetic moments in the anti-parallel direction and are termed SPIN DOWN NUCLEI Net Magnitization Vector (NMV) - correct answer reflects the relative balance between spin up and spin down nuclei B 0 - correct answer the static external magnetic field What is the basis of MRI - correct answer the interaction of the NMV and B0 What is the unit of B0 - correct answer Tesla or Gauss 1T= 10,000 G Precession - correct answer the additional spin or wobble of the magnetic moments of hydrogen around B0 Precessional path - correct answer the magnetic moments to follow a circular path around B0 Unit of precessional frequency - correct answer Megahertz (MHz) 1MHz is one million cycles or rotations per second The Larmar equation - correct answer W0= B0 x /^ W0 = - correct answer precessional frequency B0= - correct answer magnetic field strength of the magnet / - correct answer Gyromagnetic ratio Gyromagnetic Ratio - correct answer expresses the relationship between the angular momentum and the magnetic moment of each MR active nucleus. It is a CONSTANT and is expressed as the precessional frequency of a specific MR active nucleus at 1 T The gyromagnetic ratio of hydrogen - correct answer 42.57 MHz/T ex. at 1.5 T the p.f of hydogen is 63.86 MHz (42.57MHz x 1.5T) Resonance - correct answer a phenomenon that occurs when an object is exposed to an oscillation perturbation that has a frequency close to its own natural frequency of oscillation Excitation - correct answer The application of an RF pulse that causes resonance to occur Flip Angle - correct answer The angle the NMV moves out of alignment *USUALLY 90 degrees Phase - correct answer the position of each magnetic moment on the precessional path around B0 at any given time IN PHASE (COHERENT) - correct answer are in the same place on the precessional path around B0 OUT OF PHASE (INCOHERENT) - correct answer NOT in the same place on the precessional path