Magnetic Resonance Imaging (MRI) Practice Test

Which of the following would NOT help in reducing scan time in MRI?

1. Increasing NEX

2. Reduction in ETL

3. Decreasing slice thickness

4. Increasing the FOV

The correct answer is: Reduction in ETL

Reducing the echo train length (ETL) contributes to shortening the overall scan time in MRI because a shorter ETL means fewer echoes are collected for each excitation pulse, allowing for a quicker completion of a single image. Therefore, a higher ETL would actually increase scan time, while a reduction in ETL would be beneficial to decrease it. Increasing the number of excitations (NEX), decreasing slice thickness, and increasing the field of view (FOV) would generally lead to longer scan times. Increasing NEX implies acquiring multiple signals for each slice, leading to longer scans. Decreasing slice thickness increases the number of slices that may need to be taken for the same anatomical coverage, also potentially increasing time. Increasing FOV might demand more data to be gathered from a larger area of interest, thus contributing to longer acquisition times. In essence, the choice indicating a reduction in ETL is the only one that directly aligns with a strategy to decrease scan time, making it the correct identification of an option that would not assist in achieving a lower scan duration.