New Quiz 19 Dec Welcome to your MRI - A Name [With the parameters given, which protocol has the longest acquisition time?] Long TR/Low NEX/Low matrix Short TR/High NEX/Low matrix Short TR/Low NEX/High matrix Long TR/High NEX/High matrix None . [Figure displays an example of what type of artifact?] Phase mismapping Aliasing Chemical shift Cross excitation None Comment . [The strength of an MRI magnet is most commonly represented by a unit of measurement called _______.] Amps Kilogauss Tesla Ohms None . [Complete medical history should include which of the following?] Patient age, sex, and weight Current physical symptoms Previous surgeries and associated medical problems All of the above None . [The diffusion of fluid thorough a semipeITI1eable membrane such as the wall of a living cell is known as _____.] Hydrosis Ionization Osmosis None of the above None . [The return of longitudinal magnetization to equilibrium is known as _______.] T I relaxation Spin-Lattice relaxation Longitudinal relaxation All 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 . [The condition that occurs in a gradient echo pulse sequence when the TR is shorter than the T 1 and T2 relaxation times of tissue is known as ______. ] Chemical shift Steady state Frequency shift Phase shift None . [When the number of excitations is decreased, acquisition time _______.] Increases Decreases Stays the same None . [Blood flow that receives a 180 degree rephasing pulse but not a 90 degree excitation pulse produces what type of signal?] High signal Low signal No signal None . [Phase mismapping artifact caused by respiratory motion can be decreased by which method?] Presaturation pulse Swapping phase and frequency direction Respiratory compensation All of the above None . [In a T2 weighted image, tissues with long T2 relaxation times appear ______.] Hyperintense Hypointense lsointense None of the above None . [Figure is a diagram showing what type of pulse sequence?] Partial saturation Spin echo Inversion recovery Gradient echo None Comment . [When the direction of blood flow is the same as the direction in which slices are acquired, the effects of entry slice phenomenon ______.] Increase Decrease Stay the same None . [Which of the following is an advantage of a permanent magnet MRI system?] Very heavy Low operating costs Fixed field strength Limited field strength None . [Another name for transverse relaxation is _______.] Spin-Lattice relaxation Tl relaxation Spin-Spin relaxation Longitudinal relaxation None . [In figure, at a TE of 90, which of the following tissues has the greatest signal intensity?] Tissue A Tissue B Tissue C None Comment . [Which of the following is a requirement for a chemical before it can be used as an MRI contrast medium?] It must decrease magnetic relaxation times Must be non-ionic Must be biologically compatible with the human body Both A and C None . [Three characteristics commonly used to define the quality of an MRI image are _______.] Contrast, Resolution, Matrix Resolution, Contrast, Signal to noise Signal to noise, Excitations, Contrast Resolution, Matrix, Signal to noise None . [In a gradient echo pulse sequence, transverse magnetization that is leftover from a previous excitation pulse is known as ______. ] Residual transverse magnetization Magnetization transfer Chemical misregistration None of the above None . Time's up
