A. driving while intoxicated
B. magnetic resonance angiography
C.PWI
D. bold
E. madam
2. Regarding the expression of nuclear magnetic phenomena, the correct statement is: ()
A. the spin frequency of protons is proportional to the magnetic field strength.
B.MRI imaging atoms are oxygen atoms.
C. the residual spin belongs to high-energy atoms.
D. Any nuclear spin can produce nuclear magnetism.
E. In the process of nuclear magnetic resonance imaging, the frequency of RF pulse must be consistent with the precession frequency.
3. Belong to superparamagnetic contrast agent is: ()
A. gadolinium gluconate
B. disodium manganese salt
C. gadolinium bemeglumine
D. superparamagnetic iron oxide
E. gadolinium diamine
4. The description of DWI is correct: ()
A. noninvasive assessment of tissue perfusion status
B. The larger the dispersion coefficient, the stronger the dispersion motion of water molecules.
C. the higher the apparent dispersion coefficient, the higher the signal on DWI.
D. The diffusion distances of molecules dispersed in the same direction are not equal.
E-DWI is the only non-invasive technology to detect the metabolism, biochemistry and quantitative analysis of compounds in living organs and tissues.
5. The following statements about window width and window level are incorrect: ()
A increasing the window width will enlarge the range of CT values, increase the image level and worsen the contrast, for example, observing bones and cartilage.
B. Narrowing the window width will narrow the range of CT values, reduce the image level and increase the contrast, such as observing brain tissue.
C, increasing the window level to make the image white; When the window level is lowered, the image becomes black.
D the CT value of the window position is consistent with the CT value of the region of interest.
E. Window technology is an adjustment technology to adjust image contrast and brightness according to the needs of diagnosis, including window width and window level.
6. Regarding partial volume effect and peripheral gap phenomenon, the following statement is wrong: ()
A in the same scanning plane, the CT value of the interface between two adjacent tissues with different densities cannot be accurately measured, which is called peripheral gap phenomenon.
B. When two or more tissues with different densities overlap each other in the same scanning plane, the measured ct value cannot truly reflect the real CT value of any tissue in the unit volume of the plane, which is called partial volume effect.
C. The method to reduce partial volume effect and surrounding void phenomenon can be thin-layer scanning.
D. the CT value of low-density lesions in high-density tissues is low.
E. the CT value of high-density lesions in low-density tissues is low.
Reference answer and analysis
1. Reference answer B. Analysis: MRA is magnetic vibration angiography, not functional imaging. Functional imaging includes DWI (Diffusion Imaging), PWI (Perfusion Imaging), BOLD (Oxygen Level Dependent Imaging) and MRS (Proton Spectroscopy Imaging).
2. Reference answer E. Analysis: (1) According to the formula W=? B0, the frequency of proton precession is proportional to the magnetic field strength. (2) The nucleus can spin only when at least one proton or neutron is odd. (3) The residual spins belong to low-energy atoms and are arranged along the main magnetic field. (4)MRI imaging atoms are hydrogen atoms, because hydrogen atoms have high content, wide distribution and high magnetic susceptibility.
3. Reference answer D. Analysis: Magnetic sensitive contrast agent: (1) Paramagnetic contrast agent: It is composed of paramagnetic metal elements, such as Gd and Mh. When the contrast agent concentration is low, T 1 is mainly shortened and the signal is enhanced. When the concentration is high, the tissue T2 is shortened beyond T 1 effect, and the MR signal is decreased. (2) Superparamagnetic contrast agent: refers to a contrast agent composed of various magnetic particles or crystals with magnetization between paramagnetism and ferromagnetism. Such as superparamagnetic iron oxide (SPIO). (3) Ferromagnetic contrast agent: It is composed of a group of closely arranged atomic crystals, and its magnetic moment exists in the magnetic domain. Even if there is no external magnetic field after magnetization, it still has certain magnetism.
4. Reference answer B. Analysis: (1)PWI non-invasive assessment of tissue perfusion status. (2) About DWI: ① Isotropic dispersion: In a completely homogeneous medium, because there are no obstacles, the movement distance of molecules in all directions is equal. ② Anisotropic dispersion: it has direction dependence. In a tissue arranged in a certain direction, the diffusion distance of molecules in all directions is unequal. ③ Dispersion coefficient: The numerical value for measuring dispersion is called dispersion coefficient, which is expressed by D. The greater the value of D, the stronger the dispersion movement of water molecules. ④ Apparent diffusion coefficient (ADC): The higher the ADC value, the stronger the diffusion movement of water molecules in the tissue, and the lower the ADC value, the higher the signal on DWI. (3) At present, MRS is the only technique for noninvasive detection of metabolism, biochemistry and quantitative analysis of compounds in living organs and tissues.
5. reference answer C. analysis: this question examines the relevant expressions of window width and window level. Window technology is an adjustment technology to adjust the contrast and brightness of images according to the needs of diagnosis, including window width and window level. Window width refers to the range of CT values, in which all gray levels on CT images are effectively displayed. Window position refers to the center of the window, that is, the central value of the window width, which is consistent with the CT value of the region of interest. Increasing the window width will increase the image level, reduce the tissue contrast and display poor details; When the window width decreases, the image level decreases, the tissue contrast increases and the details are displayed well. Increase the window level, the image becomes black; Lower the window level and the image will turn white. So the answer is C.
6. reference answer D. analysis: this question examines the relevant expressions of some volume effects and peripheral void phenomena. Partial volume effect means that when two or more tissues with different densities overlap each other in the same scanning plane, the measured ct value does not really reflect the real ct value of any tissue in the unit volume of the plane, but the average CT value of these tissues. The phenomenon of peripheral space means that the CT value of the interface between two adjacent tissues with different densities can not be accurately measured in the same scanning plane, so the image of the interface can not be clearly distinguished on the CT image. The method to reduce partial volume effect and surrounding void phenomenon can be thin-layer scanning. Due to the homogenization of CT values, the measured CT values of low-density lesions in high-density tissues are higher. However, the high-density lesions in low-density tissues have lower CT values because of the homogenization of CT values. So the answer is d.