- 00000018WIA30518870GYZ
- id_400239471.2
- Feb 7, 2022 12:16:02 PM
PROPELLER artifact
There are a number of artifacts that are either unique or are manifested differently when using PROPELLER. Each is illustrated below along with suggestions to minimize the artifact.
Consider the following trade-offs when prescribing PROPELLER:
- As frequency resolution increases, the chance of crinkling (illustrated below) increases; increase ETL to reduce crinkling.
- As ETL increases, TE increases; increase Bandwidth to lower TE.
- As Bandwidth increases, SNR decreases.
Crinkling
The crinkling on PROPELLER acquisitions can be caused by:
- The wrong ETL. The wider the blade (determined by ETL), the more data for blade comparison and correction.
- This may appear in the superior slices. The most common cause is low ETL prescriptions.
- Increase the ETL.
| Number | Description |
|---|---|
| 1 | ETL is 20 (TE = 90) |
| 2 | ETL is 28 (TE = 126) |
- Extreme patient movement
- Patient movement during any acquisition will result in sub-optimal images. In PROPELLER, the image may be captured at an angle.
- Increasing the ETL may result in better motion reduction, but as with all motion-induced artifacts, eliminating patient movement is the best solution.
- Phase Wrap
Be sure the FOV fully contains the anatomy.
Top of scalp artifacts
Top of scalp artifacts are caused by not having enough data to perform motion correction.
Prescribe fewer slices to cover only anatomy of interest.
| Number | Description |
|---|---|
| 1 | Top of scalp |
| 2 | Extreme top of scalp displaying white pixels |
| 3 | Extreme top of scalp displaying noise and white pixels |
Blurred images
Blurred images can be seen with all three PROPELLER applications and results from a failure to match enough blades. If the acquired blades correlate poorly with each other, the following message appears in the GE syslog:
“Image quality may be degraded due to poor blade correlation…".
Signal voids
Signal voids can appear in diffusion weighted images produced by DW PROPELLER and are often indicated by black holes, but it may not occur with every scan.
Signal voids may be caused by system calibrations out of spec (e.g., eddy currents).
Contact service to ensure the system is within specification.
Ripples
Ripples can be caused by wrap and can be seen with all three PROPELLER applications, but looks different due to the radial acquisition.
To avoid wrap, increase the FOV and/or reposition the slice prescription.
RF Leak
