Question

Using a Spin Echo sequence, TOF will show black blood (darker than the background stationary tissue). This phenomenon is called TOF Loss or High-velocity Signal Loss. It happens because, since they are moving, flowing protons do not remain in the selected slice long enough to be exposed to both the 90RF and the 180RF pulses.

A. True
B. False

Answer 1

TOF Loss or High-velocity Signal Loss, where blood appears as black on an MRI using a Spin Echo sequence, is true and occurs due to flowing protons not being exposed to both the 90RF and the 180RF pulses.

Step-by-step explanation:

The claim that using a Spin Echo sequence, TOF will show black blood (darker than the background stationary tissue) is true. This phenomenon is known as TOF Loss or High-velocity Signal Loss. The reason for this occurrence is that the flowing protons in blood are moving too quickly to remain in the selected imaging slice to be exposed to both the 90-degree Radio Frequency (RF) pulse and the subsequent 180-degree RF pulse used in the Spin Echo sequence. Since the protons are missing the second pulse due to their rapid movement, this causes the signal from the flowing blood to be lost, resulting in a dark appearance on the image.