New Quiz 19 Dec Welcome to your MRI - A Name [The effect of MRI contrast media on tissue relaxation rates is known as_____.] Relaxation Relaxivity Realization None of the above None . [Figure displays an example of what type of artifact?] Phase mismapping Aliasing Chemical shift Cross excitation None Comment . [The precessional frequency of hydrogen is influenced by its chemical environment.] True False None . [Another name for phase mismapping artifact is ______. ] Ringing Aliasing Ghosting Truncation None . [The effects of entry slice phenomenon are dependent upon which factor( s)?] Repetition time Slice thickness Velocity offlow All of the above None . [Which of the following patients should be absolutely excluded from having an MRI exam?] Patients with hip replacements Patients with titanium aneurysm clips Patients with cardiac pacemakers Patients with cornea implants None . [When echo time is increased, signal to noise ratio _______.] Increases Decreases Stays the same None . [Dr. Raymond Damadian was inducted into the National Inventors Hall of Fame for his invention of the first human scanner in what year?] 1974 1978 1982 1989 None . [The Y gradient alters the magnetic field strength along which axis?] Horizontal axis Vertical axis Long axis Short axis None . [Metal implants within the body, depending on the location, can pose what type of problems during the MRI exam?] Torque Heating Artifacts All of the above None . [As blood flow velocity decreases, the effects of time of flight phenomenon] Increase Decrease Stay the same None . [The rule that is used to determine the direction of the magnetic field in an electromagnet is known as _____.] Ohm'sLaw Right hand thumb rule Left hand thumb rule None of the above None . [Typical peak velocities of the middle and anterior cerebral arteries are usually within what range?] 150 - 175 cm/sec 100 - 150 cm/sec 40 - 70 cm/sec 30 - 50 cm/sec None . [After being placed in an external magnetic field, low energy hydrogen nuclei point in which direction?] Parallel Anti-paired Anti-parallel Perpendicular None . [Which of the following is a type of image that is produced by phase contrast MRA?] Magnitude image Frequency image Phase image Both A and C None . [During the acquisition of axial images of the body with the phase direction A/P, frequency encoding is performed by which physical gradient?] X gradient Y gradient Z gradient None of the above None . [With the parameters given, which protocol gives the highest signal to noise ratio?] Thick slice/Low TE/Large FOV Thin slice/High TE/Small FOV Thick slice/High TE/Small FOV Thin slice/Low TE/Small FOV None . [Which of the following is an example of an intra axial neoplasm?] Acoustic neuroma Meningioma Astrocytoma Both A and B None . [In MRI, thick slices are achieved by applying a ______ gradient slope or a _______ bandwidth.] Shallow, Broad Steep, Narrow Shallow, Narrow None of the above None . [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 . Time's up
