All of the following would aid in reducing scan time EXCEPT:

The choice associated with a reduction in ETL (Echo Train Length) is the correct answer to this question. ETL pertains to the number of echoes that are collected in a single repetition time (TR) during a fast spin-echo sequence. While it is true that a higher ETL can often allow for quicker acquisition of data because multiple echoes are captured simultaneously, this does not inherently reduce overall scan time as effectively as the other methods listed. In fact, increasing the ETL may lead to longer scan times due to longer individual echo times and other pulse sequence characteristics that could complicate the imaging process.

On the other hand, increasing the parallel imaging factor does effectively reduce the amount of time required to gather the same amount of data by utilizing multiple coils to accelerate the imaging process. Similarly, a reduction in NEX (Number of Excitations) decreases the number of times the same slice is exposed to the magnetic field, directly correlating with shorter scan times. Utilizing the coarsest matrix possible can also reduce scan time since less data is acquired, thereby improving efficiency during the imaging process.

Thus, while each of the other options directly contributes to decreasing scan times, a reduction in ETL does not facilitate the same level of time efficiency, making it