Question

If a phase resolution (sharpness part of matrix) of 256 is desired, how many times does the TR period (time from initial 90 pulse to the next 90 pulse) have to be repeated?

A)256 times
B)384 times
C)Never
D)512 times

Answer 1

For a phase resolution of 256 in MRI, the TR period must be repeated 256 times to achieve the desired resolution. Each repetition corresponds to a unique phase encoding step necessary for building up the high-resolution image data.

Step-by-step explanation:

If a phase resolution (sharpness part of matrix) of 256 is desired in Magnetic Resonance Imaging (MRI), the TR period (time from initial 90-degree pulse to the next 90-degree pulse) must be repeated corresponding to the desired resolution. Therefore, for a phase resolution of 256, the TR period needs to be repeated 256 times, once for each phase encoding step required to build up the image data.

During MRI, spatial encoding is accomplished by varying the phase and frequency of the signals collected from the body. Each line of k-space data that is acquired corresponds to a different phase encoding gradient and therefore, the more lines of k-space filled, the higher the resolution of the image. To achieve a phase resolution of 256, it requires 256 unique phase encoding steps, thus the TR period is repeated 256 times to fill all the lines in k-space required for that resolution.

Answer: A)256 times