20 Questions
Which artifact causes the misplacement of signal from fat in the image?
Chemical shift artifact
What can chemical shift artifact create in areas where fat and water interface?
Both signal voids and signal superimposition
What is the appearance of chemical shift artifact in the image?
Signal loss
What is the artifact often referred to as?
Bas-relief artifact
What is the cause of chemical shift artifact?
Different chemical environments of fat and water
What is the difference in the precessional frequencies between magnetic moments in fat and water called?
Chemical shift
What is the overall appearance of chemical shift artifact in the image?
Embossed effect
What does fat consist of?
Hydrogen arranged with a chain of carbon atoms
What is the term used to describe triglyceride fat molecules as a result of self-shielding?
Self-shielding
What is the term used to describe the lowering of the Larmor frequency of the magnetic moments of hydrogen nuclei in fat?
Chemical shift
Which unit is used to express the amount of chemical shift?
Parts per million (ppm)
What is the value of the chemical shift between fat and water?
3.5 ppm
At 1.5 T, what is the difference in precessional frequency between fat and water?
220 Hz
At 1.0 T, what is the difference in precessional frequency between fat and water?
147 Hz
At lower field strengths (0.5 T or less), what is the difference in precessional frequency between fat and water?
Lower and usually insignificant
What causes chemical shift artifact in MRI images?
Difference in frequency between fat and water
What determines the bandwidth of each pixel in an MRI image?
Receive bandwidth
At a field strength of 1.5 T, how many pixels apart are fat and water protons mapped if the individual frequency range of each pixel is 125 Hz?
3.52 pixels
At an FOV of 240 mm and 256 frequency columns, what is the pixel size?
0.93 mm
At a receive bandwidth of 32 KHz and 256 frequency pixels, what is the bandwidth of each pixel?
250 Hz
Test your knowledge on chemical shift artifact and its appearance in medical imaging. Learn about the misplacement of fat signal, signal voids, and signal superimposition in areas where fat and water interface. Explore how this artifact affects the renal area and its implications in medical diagnosis.
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