• Object ID: 00000018WIA30EF1970GYZ
  • Topic ID: id_40023466 Version: 1.2
  • Date: Jan 9, 2022 12:30:13 PM

Full Echo Train

Full Echo Train allows a larger TE range for the second echo. It allows each echo to have a full echo train. If Full Echo Train is not selected, then the programmed ETL is split between the two echoes. For example, if a 16 ETL is programmed, then 8 ETL is used for the first echo and 8 ETL is used for the second echo.

Figure 1. 8 ETL with Full Echo Train off (split echo train): 1 = TE1, 2 = TE2
Figure 2. 8 ETL with Full Echo Train on: 1 = TE1, 2 = TE2, 3 = 90, and 4 = 180

Use the Full Echo Train Imaging Option with two-echo, FSE sequences. The Full Echo Train method completes all echo trains for Effective TE1 before Effective TE2 is initiated. The phase encoding process is altered to place the central phase encodings at the selected Effective TE1 or TE2.

  • Full Echo Train can result in a decrease in the number of available slices per acquisition. To compensate for the loss of slices, increase the TR.
  • The resulting contrast may be more varied than desired. An alternative is to acquire two separate acquisitions, each with an Effective TE and ETL programmed to produce the desired contrast and time results. For example, a PD-weighted protocol uses a short ETL (4 to 8) with a short TE, and a T2-weighted protocol uses a long ETL (12 to 24) with a long TE (> 100 ms).