Question

Question Posted 05/05/15:
Hi,

We are using the ADNI1 protocol for the MPRAGE sequence. We used a Siemens 3T Trio scanner with a 20 channels coil until recently and we are now changing for a Siemens 3T Prisma with a 64 channels coil. We noticed an artifact on the MPRAGE image (https://onedrive.live.com/redir?resid=6B2B34591E3F4A1D!2119&authkey=!ACRQ8W0xXL2MKxM&v=3&ithint=photo%2cpng). We used the same protocol as before and we did not change any parameters for the prisma scanner. Do you have any ideas how to get rid of this artifact?

Thanks,

Hervé Lemaitre
Response posted 05/07/15 by ADNI MRI Core:
Thank you for your question to the ADNI MRI Core.

We have recently been made aware of this as well. After checking with Siemens, we have found is that this type of artifact is usually the result of an insufficient spoiler gradient. It’s not something that you can necessary adjust in the protocol, but instead something Siemens is working on to adjust at the pulse sequence level. We think that the artifact has been present for a while, but the improved SNR of the 32 and higher channel coils is bringing it out more. One of the recommendations we received would be to run this as a Sagittal and turn the excitation to "Non-selective" pulse. If running it as an axial, then it is turned to "Slab Selective".

Hopefully this artifact is taken care of in future hardware/software releases.

ADNI MRI Core