In a Fast Spin Echo (FSE) sequence, how can blurring be reduced when T1 or PD weighted images are acquired?

In a Fast Spin Echo (FSE) sequence, using a shorter Echo Train Length (ETL) can help to reduce blurring in T1 or Proton Density (PD) weighted images. The reason for this is related to how the echo train operates during image acquisition.

When a longer ETL is used, multiple echoes are captured during a single repetition time (TR). This increases the amount of signal collected but can also lead to motion blurring, particularly in sequences sensitive to T1 or PD contrast. If tissues or structures are moving or if there is any inhomogeneity between the slices, longer ETLs may result in overlapping echoes that can blur the final image.

By shortening the ETL, fewer echoes are acquired per TR, which means each echo is more distinct with less chance of overlap and motion artifacts. This produces sharper images since each echo captures more focused information from the tissues, enhancing the overall image clarity. Therefore, selecting a shorter ETL is a practical approach to mitigate blurring and improve image quality in T1 and PD weighted acquisitions.