Object ID: 00000018WIA30750970GYZ
Topic ID: id_40022053 Version: 1.9
Date: Aug 17, 2022 5:48:52 PM

MUSE

About this task

Use these steps to acquire high resolution, multi-shot DWI/DTI scans: MUSE application. It acquires a segmented scan in the phase encoding direction, which mitigates shot-to-shot motion-induced phase errors inherent in multi-shot diffusion and diffusion tensor scans. The result is images with reduced blurring and susceptibility artifacts. Note that it does not correct voluntary patient motion artifacts.

Table 1. Image legend
Number	Description
1	MUSE de-selected. Note the blurring and susceptibility artifacts.
2	MUSE selected from the PSD/Application screen.

Step-by-step instructions

Start a scan session.
MUSE is compatible with all coils with 8 channels or more.
From the Workflow Manager, click Add Task > Add Sequence.
From the Protocol screen, select a MUSE protocol from your site or GE library.
- At a minimum, include a localizer and MUSE series.
- MUSE automatically selects ASSET and thus a calibration scan must be acquired. From the Details screen > Calibration in Prescan menu, select On. For details, see Calibration scan procedure.
- If you cannot locate a MUSE protocol in either library, then from the Protocol screen:
  1. From the GE protocol library, click the Template tab.
  2. Click the Applications folder.
  3. From the Applications list, click MUSE and add it to the Multi-Protocol Basket.
  4. Click Accept.
Acquire a 3-Plane localizer.
From the Workflow Manager, select the MUSE series and click Setup.
1. Make scan parameter adjustments, as needed.
  - From the PSD/Applications/Imaging Options screen, select any compatible Imaging Options.
  - From the details screen, select a matrix values. MUSE allows larger matrix sizes in comparison to conventional single shot DWI or DTI scans.
  - From the Details tab, select Number of Shots. The minimum number of shots is 2.
  - From the Acceleration tab, select a Phase value.
2. Click the Advanced tab and make adjustments as needed.
  - Ramp Sampling with single shot and high frequency values decreases geometric distortion.
  - Recon Type
  - Shim Volume Mode
  - TR Range for Auto TR, for details see Use TR Auto.
3. Graphically deposit and position the slice.
If desired, see Add post-process task. There are multiple compatible post-process tasks if Diffusion Direction is selected from the Diffusion tab is set to All.
- The Diffusion Weighted Imaging (DWI: ADC; eADC) scan post-process task screen allows four selections.
  - Threshold setting. For details, see Threshold adjustment.
  - Confidence level setting. For details, see DWI Optional procedure.
  - Kernel size setting. For details, see DWI Optional procedure.
  - Generation of ADC and eADC maps. For details, see DWI scan protocol considerations.
  - EPI Correction function. Select to automatically remove distortions by scaling, de-skewing, and translating each image to align it with the reference image. For more details, see EPI correction/ Motion correction.
- For Pasting details, see Scan with Auto Paste.
- The AutoBind scan post-process task allows manual or auto.
When the prescription is finished, click Save Rx > Scan.

Results

Consideration this information when acquiring a MUSE scan.

It is not compatible with EPI FLAIR.
It is not compatible with PROPELLER DWI.
Image reconstruction time is slightly longer in comparison to a DWI or DTI scan.
Image annotation:
- epi2muse
When all of the anatomy is not included in the phase FOV, a sharp line may appear across the images. If this occurs, repeat the scan and use a larger FOV to remove the artifact.
Figure 2. Scan acquired with no air around Phase FOV with end result of artifact

Scan acquired with air-to-air in the phase FOV with MUSE Diffusion. The addition of anterior and posterior saturation bands help to reduce motion and artifacts from fat.

Figure 3. Scan with air-to-air space around FOV

The inherent susceptibility-induced geometric distortions in EPI-based DWI and DTI scans can be reduced by applying ASSET Imaging Option. ASSET requires a calibration scan and a mismatch between the calibration scan (RF sensitivity profile) and the EPI-based DWI/DTI scan due to susceptibility effects and motion might result in aliasing of bright structures such as eyeballs in T2 (b=0) and/or lower b-value images [1], see the following image. In the case of MUSE, potential shot-to-shot mismatch due to motion/inherent phase errors coupled with higher resolution images might exacerbate the problem such that aliasing artifacts from bright structures (e.g eyeballs) could be seen more frequently [2]. It is also important to note that derived images such as ADC and FA maps will also show this artifact if it is visible on lower b-value and/or T2 (b=0) images.

SAT band placement over the eyeballs was reported in literature as an effective way to mitigate eyeball aliasing [1]. Care should be taken to avoid inadvertent suppression of signals from the region of interest.

Table 2. Image legend
Number	Description
1	Example of eyeball ghosting in a single-shot EPI scan.
2	Example of eyeball ghosting in a multi-shot-EPI scan.
3	SAT band placement over eyeballs mitigates the eyeball artifact.
4	Mitigated the eyeball artifact from SAT band.

[1] Chou, M-C., et al. "Pseudolesions arising from unfolding artifacts in diffusion imaging with use of parallel acquisition: origin and remedies." American journal of neuroradiology 28.6 (2007): 1099-1101.

[2] Chang, Hing‐Chiu, Shayan Guhaniyogi, and Nan‐kuei Chen. "Interleaved diffusion‐weighted improved by adaptive partial‐Fourier and multiband multiplexed sensitivity‐encoding reconstruction." Magnetic resonance in medicine 73.5 (2015): 1872-1884.