• Object ID: 00000018WIA304BD870GYZ
  • Topic ID: id_40024464 Version: 1.4
  • Date: May 22, 2022 11:32:19 AM

3D MDE

Consider this information when modifying Fast GRE scan parameters for a cardiac scan. For specific scan parameter values, select a protocol from your GE or Site library.

  • 3D MDE cardiac breath hold scan selections: 3D Mode, Gradient Echo family, Fast GRE pulse, Imaging Options: IR-Prepared and Cardiac Gating must be selected. Navigator and ASSET are compatible.

General considerations

  • 3D Fast GRE with IR Prepared uses a non-slice selective IR pulse that allows for multiple locations to be acquired within a single breath hold. IR-Prep requires a Prep Time to be entered in the Scan Parameters area. Choose a value that best suppresses the myocardium.
  • With 3D Fast GRE IR Prep, a k-space sampling technique, VAST, partitions the phase steps into two unequal segments that are acquired over multiple RR intervals. To make the scan time suitable for a breath hold scan, NEX is fixed at 0.5 NEX and cannot be modified. The scan time is reduced to approximately 20 to 25 seconds and is calculated by the number of locations x number of RR intervals.
  • If Cine IR is used to estimate the best TI for myocardial nulling, set the # RR interval =1 for Cine IR, even if 3D MDE is acquired with a different number of RR interval. 3D MDE acquisitions always plays every RR interval, which is different in comparison to 2D MDE and PSMDE acquisitions.
  • The acquisition window that determines the Temporal Resolution in 3D MDE varies proportionally with TR, Phase Encoding matrix and Phase FOV values. It is inversely proportionally with ASSET factor and the # of RR intervals.
  • To reduce cardiac motion and improve image quality, optimize the scan parameters to make the Temporal Resolution a maximum of 20% of the effective TR, which is equal to the RR interval.

Scan parameter

  • NEX: When Navigator is selected, VAST technique is turned off and NEX option becomes available.
  • Slices per Slab: If it is less than 10 locations, the SNR may be reduced too much.

User CV

Click the Advance tab to view the available User CVs. The CVs may vary based on the field strength and selected scan and imaging parameters.