ARRT review - MRI registry review program questions and answers

An RF pulse of what flip angle will maximize the component of the net magnetization projected into the transverse plane? a. 180 b. 120 c. 90 d. 45 c. T1 relaxation refers to ____ relaxation. a. spin-spin b. longitudinal c. phase d. transverse b. Which of the following statements is false? a. T1 relaxation refers to longitudinal recovery of magnetization while T2 relaxation refers to the transverse decay of magnetization b. T1 relaxation and T2 relaxation occur simultaneously c. echoes collected in the transverse plane demonstrate only T2 relaxation differences d. T2 relaxation occurs much more quickly than T1 relaxation c. If the precessional frequency of the patient's protons is approximately 21 MHz, what magnetic field strength is being experienced by the patients protons? Larmor frequency equation W0= B0 x Y 21= 42.6 x (X) 21/42.6 = .4929 (round) = 0.5T Which of the following is the definition of T1 relaxation? a. the time is takes the net longitudinal magnetization of protons to grow 63% of its final amplitude b. the time at which is takes the transverse magnetization has decayed 63% of its full value a. Based on the graph of longitudinal relaxation shown above, which of the following would have the brightest signal intensity on T1 image? a. bone marrow b. intervertebral disk c. CSF d. muscle (post test 1; page 1) a. Based on the graph of longitudinal relaxation shown above, which of the following would have the shortest T1 relaxation time? a. bone marrow b. intervertebral disk c. CSF d. muscle (post test 1; page 1) a. The edema associated with pathology in the brain has a much longer T2 relaxation time than surrounding normal brain tissue. On a T2 image, what does this result in? a. isointense between edema and surrounding normal brain tissue b. a low signal intensity in the area of edema c. a signal void in the area of edema d. a high signal intensity in the area of edema d. Which of the following dephasing mechanisms affects the size of the resulting spin echo? a. magnetic field inhomogenities b. phase effects of chemical shift c. magnetic susceptibility d. spin-spin interactions d. After a 90 RF pulse, if three 180 RF pulses are applied to generate three echoes, which of the following is responsible for the third echo being much smaller than the first echo? a. magnetic field inhomogenities b. phase effects of chemical shift c. magnetic susceptibility d. spin-spin interactions d. The MR echo is NOT: a. detected as magnetic changes that induce voltage into an RF coil b. collected when the magnetization in the transverse plane has been rephased c. a tiny signal containing contrast info. necessary for tissue differentiation d. collected only one time for a given image d. What is the time from the initial RF excitation pulse to the echo called? a. TE b. TI c. TM d. TR a. The proton's ____ contributes to its magnetic properties. 1. spinning motion 2. positive change 3. mass 1. and 2. Which of the following is TRUE regarding the hydrogen protons in a patient's body when placed in the magnet of an MR system? a. more protons align with the main magnetic field than against the main magnetic field b. more protons align against the main magnetic field than with the main magnetic field c. equal numbers of protons align against the main magnetic field d. all of the protons line up perpendicular to the main magnetic field a. On a T2 image, CSF appears bright because it has a ____ relaxation time. a. long T2 b. short T2 a. The precessional frequency of the net magnetization of protons in a magnetic field is determined by which of the following? a. the T1 relaxation times of the protons b. the gyromagnetic ratio and field strength c. the repetition time and the echo time d. spin-lattice relaxation b. The RF pulse should be transmitted at a frequency of approximately ____ MHz in order to disturb protons experiencing a 4 T field. a. 190 b. 180 c. 170 d. 42.6 c. Referring to the figure below, if the main magnetic field is aligned along the z-axis, which of the following corresponds to the correct orientation of the transverse plane? a. y-z b. x-z c. x-y d. a plane that divides the patient's L/R side (post test 1; page 2) (standard x, y, z patient coordinates- horizontal) c. Which of the following is NOT a requirement for magnetic resonance imaging? a. atomic nuclei with an odd number b. a strong magnetic field c. ionizing radiation d. RF energy c. Referring to the figure below, if the main magnetic field is aligned along the y-axis, which of the following corresponds to the correct orientation of the transverse plane? a. y-z b. x-z c. x-y d. a plane that divides the patient's L/R side (post test 1; page 2) (standard x, y, z patient coordinates- horizontal) b. What is the phenomenon called in which one proton transfers energy to another? a. precession b. rephasing c. spin-spin interactions d. echo time c. Which of the following parameters controls the amount of contrast seen in an image due to T2 relaxation? a. TR b. TE c. TI d. TM b. What is the time from the initial RF excitation pulse to the next RF excitation pulse for a given slice called? a. TE b. TR c. TI d. TM c. From a resting state in which the fully relaxed net magnetization is aligned along the longitudinal direction, what would the application of a single 45 RF pulse result in? a. equal amounts of transverse magnetization and longitudinal magnetization b. greater longitudinal magnetization than transverse magnetization c. greater transverse magnetization than longitudinal magnetization d. zero longitudinal magnetization a. Which of the following if the definition of T2 relaxation? a. the time at which the transverse magnetization has decayed to 63% of its full value b. the time at which the transverse magnetization has decayed to 37% of its full value b.