In a fast spin echo sequence with a given set of parameters, what is the calculated scan time?

The scan time for a fast spin echo sequence is determined by several parameters, including the repetition time (TR), the number of slices, the echo time (TE), and the number of averages or excitations (NEX). In fast spin echo sequences, multiple echoes are collected for each TR, which contributes to a shorter effective scan time compared to traditional spin echo sequences where only one echo is collected per TR.

To calculate the scan time, you need to consider how many TRs are required to cover the entire scan, which is generally expressed in terms of the total number of slices being imaged and the TR duration. The formula for scan time can typically be expressed as:

Scan Time = TR * (Number of Slices) * (NEX)

By applying the correct parameters to this formula, the resulting computed value gives the total duration of the scan for the sequence in question. If the calculation results in a total time of 3 minutes 7 seconds, it indicates that the chosen parameters—specifically TR and the number of slices or NEX—were set to result in that exact timing during the scan.

This particular answer choice aligns with the standard practices and calculations performed in MRI, confirming that the other options represent either longer or shorter scan