• SIGNA MR355 / SIGNA MR360
  • Service Manual
  • 5856356-3EN Revision 5.0
  • Basic Service Documentation. Copyright General Electric Company.
  • Object ID: 00000018WIA30062F20GYZ
  • Topic ID: id_13107042 Version: 3.0
  • Date: Aug 29, 2019 1:53:50 AM

HD T/R Quad Extremity Coil SNR Test

Prerequisites

Table 1. Personnel requirements
Required personsPreliminary requirementsProcedureFinalization
1Not Applicable15 minutesNot Applicable
Table 2. Tools and test equipment
ItemQuantityEffectivityPart numberManufacturer
Large cylindrical Unified Phantom1-

5342679

-
Phantom positioner1-

5147225-7

-
Table 3. Required conditions
ConditionReferenceEffectivity

Coil: QUADKNEE. Configuration: GE_HDX QUADKNEE.

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About this task

Follow this process to prepare for the SNR test using the HD T/R Quad Extremity Coil by Invivo. The SNR test process is the same (For 1.5T catalog, M3335ME) .

Phantom Setup

Procedure

  1. Place the baseplate of the coil on the patient table as shown in the Figure 1.
    Figure 1. Place the baseplate
  2. Align the alignment mark on the coil to Zero position on the Scale as shown in Figure 2.
    Figure 2. Align the alignment mark
  3. Place the Phantom Positioner as shown in Figure 3.
    Figure 3. Phantom Positioner
  4. Place the large cylindrical unified phantom in the phantom positioner as shown in Figure 4.
    Figure 4. Large cylindrical unified phantom
  5. Attach the anterior portion of the coil to the baseplate and lock the coil as shown in Figure 5 and Figure 5.
    Figure 5. Attach the anterior portion
    Figure 6. Lock
  6. Connect the Coil to respective port of the system LPCA and landmark the coil on the marks shown in Figure 7. Then advance to scan.
    Figure 7. landmark

Coil Imaging Performance Verification

About this task

The GE HD T/R Quad Extremity Coil has one (1) coil name: HD T/R QUAD EXTREMITY, and can be used in the mode QUADKNEE . Refer to the Data Sheet in Step 1, to understand the data required to calculate the individual element SNR. The image quality check uses two different protocols for signal and noise image acquisition. The signal scan is an FSE sequence used to minimize susceptibility and B0 inhomogeneity effects. The noise scan is a GRE sequence that has a Control Variable (do_noise) to eliminate the transmit RF completely during the scan. The signal scan must be run prior to the noise scan as the R1, R2, and TG values from the signal scan are used for the noise scan.

Signal Scan

Procedure

  1. From the Scan Desktop, start new scan by selecting New Pt. Set Patient ID to geservice and Patient Weight to 111 pounds. Click Patient Position to open protocols window.
  2. At the console, set the protocols per the Signal section from Table 4, Signal and Noise Protocols.
  3. Click Save Series to download the protocols, then click Prepare to Scan.
  4. Run Auto Prescan. Take note of the R1, R2 and TG values.
  5. Run Scan.

Noise Scan

About this task

A signal scan must be run prior to the noise scan as the same R1, R2 and TG values must be used for both the signal and noise scans. Do not run an Auto Prescan prior to the noise scan as the values will be changed.

Procedure

  1. Copy the signal scan series. Use Copy Series (highlight signal series and click right mouse button) and Paste Series in RX Manager.
  2. Click View Edit and set the protocols per the Noise section from Table 4, Signal and Noise Protocols.
  3. Click Save Series and click Prepare to Scan.
  4. Open Display CVs menu under Research Operations. Set the rhformat and do_noise CVs to 1.
  5. Run Manual Prescan, and do not make any changes. Verify that R1, R2, TG and Bandwidth have not changed from the previously completed signal scan, and click Done.
  6. Run Scan.
    Table 4. Signal and Noise Protocols
    Protocol Signal Noise
    Patient Exam Information
    Patient IDgeservicegeservice
    Patient Name
    Patient Weight111 lbs. (50 kg)111 lbs. (50 kg)
    Patient Position
    Patient PositionSupineSupine
    Patient EntryFeet FirstFeet First
    CoilHD T/R QUAD EXTREMITYHD T/R QUAD EXTREMITY
    Series DescriptionSignalNoise
    Imaging Parameters
    PlaneAxialAxial
    Mode2D2D
    Pulse SeqFSE-XLGRE
    Imaging OptionsFast (or None)None
    PSD NameLeave BlankLeave Blank
    ProtocolLeave BlankLeave Blank
    Scan Timing
    # of Echoes11
    TE17Min Full
    TR50034
    Echo Train Length4N/A
    Bandwidth15.6315.63
    Additional Parameters
    Flip AngleN/A1
    Acquisition Timing
    Freq256256
    Phase256256
    NEX11
    Phase FOV11
    Freq DIRR/LR/L
    Auto Center FreqPeakPeak
    AutoshimOnOn
    Phase CorrectOnN/A
    ContrastOffOff
    # of Reps B4 Pause0N/A
    Scanning Range
    FOV2020
    Slice Thickness33
    Spacing1.51.5
    S/I Start00
    R/L Center00
    A/P Center00
    S/I End00
    # Slices11
    Table Delta00

SNR Measurement

Procedure

  1. A circular ROI should be used for the signal measurements, and a rectangular ROI should be used for the noise measurements. The actual ROIs should be similar in shape and size to those in Figure 9.
  2. ROIs in both signal and noise images can be measured directly in the image browser. Click the user interface button MEASURE, select the circular or rectangular shape, and adjust its size and orientation so that the ROI is similar to those found in Figure 8. Mean, standard deviation, and area of the ROI will appear in the lower right corner of the image.
  3. For the signal measurement, choose a 10 cm diameter circular ROI. This should be approximately a 5600 mm2. For the noise measurement, choose a 19 cm rectangular ROI. This should be approximately 34000 mm2. Record the values for mean signal, standard deviation of noise, and SNR in the data sheet found in Step 1.
  4. Individual receiver SNR is defined as the mean of data within the signal ROI divided by the standard deviation of data within the noise ROI.
    Figure 8. SNR Calculation
    Note:

    The SNR calculation uses the MEAN of the signal image and STANDARD DEVIATION of the noise image.

    Figure 9. Example ROIs

    The SNR measurements must be greater than or equal to the following specifications:

    Table 5. SNR Specifications
    Plane (if applicable) SNR (1.5T)
    HD T/R QUAD EXTREMITY Coil200

Finalization

Procedure

Use the table provided below to record the calculated signal to noise ratio (SNR) data obtained from the Functional Checks section. 538814.pdf