New Quiz 19 Dec Welcome to your MRI - A Name [The signal produced after the 180 degree RF pulse is applied is known as a_______.] Gradient echo signal Spin echo signal Spin spin signal FID signal None . [An artifact that is caused by an external radio frequency leak is known as ______.] Shading artifact Zipper artifact Starring artifact Herringbone None . [When a patient is placed in an external magnetic field, the number of unmatched hydrogen protons usually equals _______.] One billion One million Few per million Few per billion None . [Cross excitation artifact can be eliminated by which of the following methods?] Increasing interslice gap Using a sinc RF pulse Interleaving All of the above None . [During cardiac gating, one R-R interval and a short TE is used to produce what type of image?] T1 weighting T2 weighting Proton density weighting None of the above None . [In an MR image, the degree of chemical shift artifact depends upon which parameter?] Receive bandwidth Size of the FOV Magnetic field strength All of the above None . [At 1.5 tesla, to reduce chemical misregistration artifact, the TE should be a multiple of what time?] 3.1 ms 4.2 ms 6.6ms 7.3 ms None . [Two types of cardiac gating that are most commonly used are known as______.] Respiratory gating, Respiratory compensation ECG gating, Peripheral gating Pseudo gating, Respiratory gating None of the above None . [During a fast spin echo pulse sequence, which lines of k space are filled by the gradients performed closest to the effective TE?] Central lines Outer lines Negative lines only Positive lines only None . [During an inversion recovery pulse sequence, the time between the 180 degree inversion pulse and the 90 degree excitation pulse is known as ______. ] Echo time Repetition time Inversion time Reversion time None . [In a TI weighted image, tissues with short TI relaxation times produce what type of signal?] High Low Intermediate None of the above None . [The T wave of the ECG represents which phase of the cardiac cycle?] Atrial systole Ventricular systole Ventricular diastole Atrial diastole None . [As the echo time increases, the effects of time of flight phenomenon ______. ] Increase Decrease Stay the same None . [At a field strength of 1.0 tesla, the approximate Tl relaxation time for CSF is ______.] 800ms 1000 ms 2000 ms 2500 ms None . [In 1825, the British scientist, William Surgeon, constructed the first _______.] Superconducting magnet Permanent magnet Electromagnet None of the above None . [The flow phenomenon that is characterized by the contrast differences between fresh flowing nuclei entering a slice and stationary tissue within that slice is known as ______.] Time of flight phenomenon Entry slice phenomenon Intra-voxel dephasing None of the above None . [The artifact that is characterized by a loss of signal intensity in one area of an image is known as ______.] Aliasing artifact Ringing artifact Shading artifact None of the above None . [Which Parameter(s) effect total scan time?] Repetition time Number of phase encoding steps Number of excitations All of the above None . [Biological effects associated with exposure to radio frequency include which of the following?] Induction of electrical currents in tissue Heating due to tissue resistance Radiation poisoning Both A and B None . [During cardiac gating, TR is dependent upon which factor(s)?] The patient's heart rate The R- R interval The Q - R interval Both A and B None . Time's up
