• SIGNA MR355 / SIGNA MR360
  • Service Manual
  • 5856356-3EN Revision 5.0
  • Basic Service Documentation. Copyright General Electric Company.
  • Object ID: 00000018WIA302ADD20GYZ
  • Topic ID: id_13106122 Version: 3.0
  • Date: Aug 29, 2019 1:52:33 AM

Surface Coils SNR Test

Prerequisites

Table 1. Personnel requirements
Required personsPreliminary requirementsProcedureFinalization
1Not Applicable30 minutesNot Applicable

About this task

This procedure is used for several coils. Open the Coil SNR tool as shown in Figure 1, click on the square tab on the right side of the Coil selection to determine which coils are available to use with this tool.

Procedure

  1. Go to the Common Service Desktop -> Image Quality and select Coil SNR Test.
  2. Select Click here to start this tool.
  3. Select method for calculating SNR.
  4. Use the specific Coil Service manual to set up the coil and phantom for Landmark and Instructions. If the coil service manual also provides an SNR procedure, then follow that procedure. Otherwise continue with the following steps.
  5. Select file -> Help then access the proper coil.
  6. Select the coil type you want to run, then select Start Scan. See Figure 1. This illustration shows an example using the 8 channel Torso coil.
    Figure 1. Coil SNR tool
  7. After the test is complete, the tool will automatically extract and analyze the images
  8. When the scan completes, the SNR data will be displayed in the Multicoil SNR Tool Control window. Each ROI returns an individual result with a pass or fail indication. See Figure 2. The results are automatically recorded as files in /usr/g/service/data. Please refer to this directory for a history of functional tests performed on a specific system. The individual receiver images and composite image are saved in the system. The signals used to calculate SNR are taken from the composite image. Signal images are acquired using a SE sequence with CV saveinter set to 1 to save intermediate images into the image database.
    Figure 2. SNR Results
    Figure 3. Example Individual Receiver Images And Composite Image For CTL Coil
  9. After reviewing the tabular SNR data, examine the stored individual element images visually to ensure that the elements are functioning properly. This gives added insurance that all elements are functioning normally. (It is possible that the composite SNR test can show a passing result even though an element can be faulty).
  10. For most coils, a plot of the results will appear in a separate window. This also will display automatically. The Upper Spec and Lower Spec lines appear in red with the current test results shown in blue. See Figure 4.
    Note:

    The USLUpper Spec Limit can be ignored. This limit will be removed in future versions of EXCITE software.

    Figure 4. SNR Plot
  11. Optionally:
    1. To view the most recent plot data again or previous results, click on view data. The following GUI will appear. See Figure 5
      Figure 5. View Data

  12. From this menu, select plot data and view SNR data from previous runs.
  13. Select the run number from Data Plot Control GUI.
  14. Click on Plot Data to get a graphic representation of the coil SNR. See Figure 6.
  15. To recalculate the most recent exam SNR results, enter the correct exam numer in the Exam Field under the Mulitcoil SNR display control GUI, then click the Calculate SNR button. SeeFigure 6 and Figure 7.
    Figure 6. SNR plot data
    Figure 7. SNR value data

Finalization

No finalization steps.