• Object ID: 00000018WIA30430970GYZ
  • Topic ID: id_40026032 Version: 1.5
  • Date: Apr 14, 2022 8:53:13 AM

4DFLOW

About this task

Use these steps to acquire 3D cine phase-contrast images of a targeted volume (for example, whole chest or aorta), which are used to assess blood flow in the targeted volume. The acquisition is a cardiac-gated, segmented scan acquired through the entire RR cycle during a free-breathing scan. The 4DFLOW scan allows for velocity encoding in all directions.

4DFLOW is a component of ViosWorks.

Step-by-step instructions

  1. Start a scan session.
  2. From the Workflow Manager, click Add Task > Add Sequence.
  3. From the Protocol screen, select the Chest tab and a cardiac 4DFLOW protocol from your site or GE library.
    • At a minimum, include a localizer and 4DFLOW series.
    • If you cannot locate a 4DFLOW 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 4DFLOW and add it to the Multi-Protocol Basket.
      4. Click Accept.
  4. Acquire a 3-Plane localizer.
  5. From the Workflow Manager, select the 4DFLOW series and click Setup.
  6. From the scan parameters screen, make adjustments as needed.
    • Imaging Options that are automatically On and cannot be de-selected:
      • ARC
      • Cardiac Gating/Triggering
      • Extended Dynamic Range
  7. Click the Cardiac tab and make adjustments as needed.
    • Note: Both ECG and peripheral gating support 4DFLOW scans.
    • Arrhythmia Rejection Window: typically select 30.
    • # of Phases to Acquire: typically select 16.
    • # of Phases to Reconstruct: typically select 20.
    • Prospective: not selected (off).
  8. Click the Vascular tab and make adjustments as needed.
    • Velocity Encoding: Typically select 160.
    • Acquisition Flow Direction Images: Typically select All.
  9. Click the Acceleration tab and enter a HyperKat value.
    • HyperKat is an auto-calibrating recon using both spatial and temporal correlation with a k-t ARC kernel adaptive to local cardiac motion.
    • HyperKat value is displayed on the Series Text screen.
    • 8 produces optimal image quality.
  10. Click the Advanced tab and make adjustments as needed.
  11. Graphically deposit and position the 3D slab. Multi-slab is compatible with 4DFLOW.
    • Multi-slab improves overall CNR compared to a single slab. Scan time for same coverage is slightly longer due to some overlap among the slabs, which is necessary to avoid venetian blind artifact. Select the number of slabs based on the coverage needed. Typically select Slices per Slab = 30.
    • If a multi-slab acquisition is used, the slabs should be placed such that the slabs are aligned with the direction of the primary flow in the imaging volume. This maximizes the in-flow effects. For whole-chest 4DFLOW imaging, the primary flow direction is approximately superior-inferior. Therefore, the suggested image plane is axial with each slab perpendicular to the dominant blood flow along the superior-inferior direction.
    • If 4DFLOW is used with contrast, a single slab is recommended. Typically select Slices per Slab = 72.
    • Select the number of Slices per Slab. As the number of Slices per slab increases the scan time increases.
  12. If desired, see Add post-process task. Compatible post-process tasks include:
    • Maximum Intensity Projection
  13. When the prescription is finished, click Save Rx and Scan.
    • When the scan is complete, the Auto Viewer first displays preview images prior to the reconstruction of the series. This allows you to check the overall quality immediately after a scan and determine if the scan needs to be acquired again due to image quality issues (anatomy overlap, VENC too low, etc).
    • For 4DFLOW series numbering details, see Series numbering.

Results

Image transfer

4DFLOW data sets are intended to be processed on the ViosWorks cloud application powered by Arterys. Currently, this is the only available method to perform quantitative analysis. Existing applications such as Flow Analysis and Cardiac VX are not available for 4DFLOW post-processing.

Transfer image data to an Artery’s PHI server. For details, see ViosWorks send data.

Image annotation

For details, see Application annotation.

Figure 1. PSD annotation field

The annotation field for the PSD name is: 4DFLOW/XX where XX is the flip angle.

DICOM header information about heart cycle

For 3DCINE-SPGR 3DCINE-FIESTA, 4DFLOW and 2D FastCINE including 2D PC FastCINE scans, the DICOM header contains information about the cardiac cycle variations during scan. This allows a better understanding of the heart rate variation of the patient during the scan and can be used to better interpret the results.

  • The heart rate and nominal interval DICOM tags (0018,1088 and 0018,1062) show the mean heart rate/nominal interval during the scan.
  • Additionally, the minimum RR interval, the maximum RR interval, the number of rejected segments due to detected arrhythmia, and the total number of acquired segments during the scan, also are included in the DICOM header (Tags: 0018,1081- 0018,1082- 0018, 1084- 0018,1083, respectively).