MRSO Exam mark Graded A+

Which of the following describe when a non-ferrous object is repulsed by static magnetic field? a. Fourier transformation b. Lenz's force c. Ohm's law d. Larmor equation - ANSWER-b. Lenz's force What is the FDA SAR limit for the whole body in first level controlled operating mode? a. 8 W/kg for 15 mins b. 4 W/kg for 15 mins c. 3 W/kg for 10 mins d. 7 W/kg for 20 mins - ANSWER-b. 4 W/kg for 15 mins Gadolinium contains what kind of magnetism? a. Diamagnetic b. Paramagnetic c. Ferromagnetic d. Super paramagnetic - ANSWER-b. Paramagnetic Where will peripheral nerve stimulation be the strongest? a. Further away from isocenter in the gantry b. At the level of the table when it is advanced c. At isocenter d. Outside the gantry near the 5 gauss line - ANSWER-a. Further away from the isocenter in the gantry What is the name for the direction of the vector of the static magnetic field? a. Inverse field b. Equilibrium c. B0 d. B1 - ANSWER-c. B0 An object that produces a weakly repulsive force in the presence of a strong magnetic field is called what? a. Superparamagnetic b. Ferromagnetic c. Diamagnetic d. Paramagnetic - ANSWER-c. Diamagnetic The gradient coils are responsible for which of the following? Select all that apply. a. Heating b. Rotational force c. Translational force d. Magnetohydrodynamic effect e. Noise f. Peripheral nerve stimulation - ANSWER-e. Noise f. Peripheral nerve stimulation Why is magnetic shielding used in an MR unit? a. To reduce heating b. To reduce the e-fields c. To maintain field homogeneity d. To limit the fringe field - ANSWER-d. To limit the fringe field Contrast media will do what to our tissue? a. Shorten T1 relaxation times b. Shorten T1 & T2 relaxation times c. Increase T2 relaxation times and decrease T1 relaxation times d. Shorten T2 relaxation times - ANSWER-b. Shorten T1 & T2 relaxation times As blood flows through a vessel, currents can be induced. The degree of this is called? a. Magnetophosphenes b. Flow potential c. Translational forces d. Fringe field - ANSWER-b. Flow potential The T-wave in the cardiac cycle represents what? a. Heart repolarization b. Heart depolarization c. None of the choices d. Arrhythmia - ANSWER-a. Heart repolarization NSF is caused by what? a. When the patient is allergic to gad contrast b. When gad ion is excreted by the liver c. When gad ion is excreted from the body quickly d. When a gad ion breaks free from the ligand and remains in the body - ANSWER-d. When a gad ion breaks free from the ligand and remains in the body What pulse sequence will produce the most patient heating? a. Gradient echo b. Conventional spin echo c. Inverse recovery sequence d. Single shot fast spin echo - ANSWER-d. Single shot fast spin echo The allowable maximum strength of the gradient coils is called? a. Spacial gradient b. Rise time c. Slew rate d. Maximum gradient peak - ANSWER-d. Maximum gradient peak Using a headset and earplugs will reduce noise by how much? a. 50 dB b. By the NRR of the headset + NRR of earplugs c. By the NRR of the headset d. By the NRR of the headset + NRR of earplugs divided by 2 - ANSWER-b. By the NRR of the headset + NRR of earplugs Time-varying gradient magnetic fields are measured in which of the following? a. W/kg b. Tesla c. dB/dt d. dB/dx - ANSWER-c. dB/dt "d"=change in "B"=static field strength "t"=time Therefore this means that a change in static field strength over a change in time. Gad contrast will affect tissue when...? a. It touches tissues b. None of the choices c. It is in very close proximity to tissue d. It doesn't touch tissue - ANSWER-c. It is in very close proximity to tissue The FDA limits SAR in the head to what? a. 3.2 W/kg for 10 min b. 8 W/kg for 20 min c. 10 W/kg for 15 min d. 4 W/kg for 15 min - ANSWER-a. 3.2 W/kg for 10 min The gradient coils are used for what in MRI? a. Tilting nuclei in to the transverse plane b. Spacial encoding c. Resonance production d. Aligning nuclei to a vector - ANSWER-b. Spatial encoding Passive shield is performed how?