Which pulse sequence parameter combination would yield the image with the most blurring?

Which pulse sequence parameter combination would yield the image with the most blurring?

• A. TR 6000 ms, TE 80 ms, Matrix 256 x 256, Slice thickness 5 mm, ETL 16, NSA 4
• B. TR 2000 ms, TE 60 ms, Matrix 256 x 256, Slice thickness 3 mm, ETL 2, NSA 1
• C. TR 1000 ms, TE 60 ms, Matrix 512 x 512, Slice thickness 2 mm, ETL 4, NSA 2
• D. TR 4000 ms, TE 90 ms, Matrix 128 x 128, Slice thickness 5 mm, ETL 8, NSA 4

Answer: (A)

Blur is driven mainly by voxel size and how k-space data is acquired during the echo train. A thicker slice increases partial-volume effects along the through-plane, so edges become less sharp. In fast spin-echo sequences, a longer echo train length means more echoes sample while signal decays, which blurs high-frequency details and smooths edges. The combination with a 5 mm slice thickness and a very long echo train length (16) emphasizes these effects, especially since the in-plane resolution isn’t extremely high. The other options improve sharpness by reducing voxel size (thinner slices or higher matrix), or by shortening the echo train (less T2-related blurring), so they produce crisper images.