• Object ID: 00000018WIA30556970GYZ
  • Topic ID: id_40026277 Version: 1.2
  • Date: May 10, 2022 2:16:44 AM

PC: Self-Cal Phase Contrast

SCPC is an in-line post-processing task that reduces the residual phase error in 2D flow measurements. It uses non-linear fitting image-based algorithm. SCPC is intended to be used only in the vasculature around the heart.

SCPC automatically corrects phase-contrast images from background phase error for MR flow imaging. It uses areas in the image that are known to have zero velocity. The task also alerts the user to conditions when the method fails, and advices the user how to re-scan so that the feature works correctly.

Acquisition considerations with SCPC

  • SCPC can only be used as a post process task with the following scan selections:
    • 2D Mode, Vascular family, Fast 2D Phase Contrast pulse. The following Imaging Options are compatible with SCPC:
      • ASSET, which must be selected. If not, an error message displays informing you to rescan with ASSET enabled.
      • Flow Compensation
      • Respiratory Gating/Triggering
      • Sequential
      • ZIP 512, typically do not select ZIP 512 because processing time might become significantly longer.
        • SCPC is only compatible if Chest is selected as the Anatomical Region.
          Figure 1. Anatomic Region area from the Set Anatomy screen
        • SCPC only supports 1 slice per series. If 2 or more slices are prescribed in one series, the following error message will appear: Only one slice is supported by Phase Correction. Change number of Slices to ‘1’.
        • From the Vascular tab, make these selections.
          Figure 2. Vascular tab
    • Flow Recon Type = Phase Diff
    • Flow Analysis = On
    • If Oblique is selected from Scan Plane scan parameter, then Acquisition Flow Direction Images = Slice.
      Figure 3. The flow direction must be perpendicular to the scan plane
    • If an Axial, Sagittal or Coronal plane is selected from Scan Plane scan parameter, Acquisition Flow Direction Images = a scan plane perpendicular to the flow direction
      • If Scan Plane is Sagittal, select direction R/L
      • If scan plane is Coronal, select direction A/P
      • If scan plane is Axial, select direction S/I
        Figure 4. The flow direction must be perpendicular to the scan plane
        • From the Cardiac tab, if the # Phases to Reconstruct > 30, SCPC processing time could become significantly longer.
          Figure 5. Cardiac tab
        • From the Acceleration tab select 1-2.
          Figure 6. Acceleration tab
        • From the Advanced tab, select 0.0 for CV2 (Use Magnitude Weighting Mask). If it is set to 1.0, SCPC fails and an error message appears.
          Figure 7. Advanced tab
        • SCPC status messages appear in the task list. To view the message, move the cursor over Err (error) or Inv (invalid) text that appears in the Status column of the Task Manager.
          Figure 8. Task Manager information area
          Table 1. SCPC messages
          Status columnMessage displayed in Task ManagerAction
          InvOnly one slice is supported by Phase Correction. Change number of Slices to '1'.Change number of Slices to 1.
          ErrASSET must be used for Phase Correction. Rescan with ASSET enabled in Imaging Options.
          • Select ASSET from Imaging Options screen.
          • Rescan.
          ErrCV2, the indicator for Magnitude Weighing Mask, must be set to 0.00. Rescan with the CV2 set to 0.00 under the Advanced tab.
          • From the Vascular screen > Flow Recon Type menu, select Phase Difference.
          • From the Advanced tab, set CV2 to 0.00.
          • Rescan .
          ErrThe flow direction must be perpendicular to the scan plane. Check the Acquisition Flow Direction Images under the Vascular tab. Rescan with a flow direction perpendicular to the scan plane.
          • From the Vascular screen > Acquisition Flow Direction Images menu, set the value so that the flow direction is perpendicular to the scan plane.
          • Rescan.
          InvAcquisition must be multi-phase.From the Vascular screen > # of Phases to Reconstruct, enter the 30.
          InvMode must be set to ‘2D’ for Phase Correction. Change Mode to ‘2D’ in Imaging Options.From the Imaging Options/PSD screen > Mode menu, change the Mode to 2D.

          DoneNoCorrNeededBackground phase is sufficiently small and no correction is needed. No correction was performed.
          ErrVelocity images show inadequate quality to perform the Phase correction. Rescan after modifying one or more of the following parameters: increasing VENC, decreasing BW and/or decreasing matrix size.
          • Change the prescription increase the VENC, decrease BW and/or decrease matrix size.
          • Repeat the scan.
          ErrThe area containing static tissue is too small. Rescan after modifying one or more of the following parameters: increasing or rotating the FOV, decreasing BW and/or decreasing matrix size.
          • Change the prescription to include more static tissue. For example, increase or rotate the Field-of-View, decrease the BW and/or decrease the matrix.
          • Repeat the scan.
          Err/InvOnly Fast 2D Phase Contrast scanning is supported by Phase Correction. Check 1) Flow Analysis is ‘On’ under Vascular tab, and 2) Flow Recon Type is ‘Phase Diff.’ under the Vascular tab, and 3) Sequential mode is selected in Imaging Options
          • Check the following from the Vascular tab:
          • Flow Analysis option box = On
          • Flow Recon Type = Phase Diff
          • Check the following from the Imaging Options screen:
          • Sequential mode is selected
          ErrPhase Correction has failed. Perform alternative correction method.Perform alternative correction method.