What phenomenon occurs when there is a great variance of T2 decay in the echo train length (ETL)?

When there is a great variance of T2 decay within the echo train length (ETL), it leads to F/TSE blurring. F/TSE, or Fast/Turbo Spin Echo, sequences are designed to capture multiple echoes during a single excitation. However, when the T2 relaxation times of the tissues being imaged vary significantly, it can result in differing amounts of signal decay for each echo.

This variance can cause overlapping of signals from tissues with different T2 values, leading to blurring in the final image. The issue arises because the signals from tissues with shorter T2 decay out faster than those with longer T2, causing inconsistencies in the echo signals received at different times. The result is a loss of clarity and definition in the displayed images, making it difficult to distinguish between adjacent structures.

In this scenario, the other options do not directly relate to the phenomenon of variance in T2 decay affecting ETL in the same way. Signal loss typically relates to issues with receiving signals, phase cancellation pertains to spatial positioning of signals leading to voids in imaging rather than blurring, and contrast enhancement involves altering image characteristics rather than the direct effects of T2 decay variance on echo train signals.