• Object ID: 00000018WIA30D15880GYZ
  • Topic ID: id_2034910 Version: 1.6
  • Date: May 19, 2022 11:19:34 AM

Breast: manual prescan for silicon impants

Silicone implant imaging requires high-resolution images.

Before you begin

Keep the following in mind when you select a suppression technique.

Table 1. Suppression techniques
Suppression techniqueCenter frequency placementFrequency shift
Fat SATWater peak-220 Hz
Water SATFat peak+220 Hz
Silicone suppression: select a protocol with Water SATFat peak-100 Hz
Silicone suppression: select a protocol with Fat SATWater peak-320 Hz

About this task

The type of contrast required is dependent on the clinical needs.
  • Fat suppression
  • Silicone suppression for evaluating fat or other tumors
  • Bright silicone contrast for evaluating prosthesis dislocation, intracapsular or extracapsular ruptures, or capsular contractures
Table 2. Expected contrast with silicone implants
Silicone contrastPSD and SATTissue contrast
BrightSilicone bright with water SAT:
  • Use a STIR with water SAT
  • Place center frequency on the fat peak to suppress water
Figure 1. STIR with water SAT: Fat = dark, Water = dark, Silicone = bright
BrightBright silicone with Fat SAT:
  • Use a T2 FSE FS or STIR
  • Place the center frequency on the water peak to suppress fat
Figure 2. STIR: Fat = dark, Water = vrey bright, Silicone = bright
Figure 3. T2 no SAT: Fat = bright, Water = bright, Silicone = bright
DarkDark silicone with fat SAT
  • Use an FSE pulse with fat SAT
  • Place the center frequency on the water peak then manually change the frequency offset (Options menu > mrsp > csf) to that of silicone to move the fat suppression pulse
Figure 4. FSE fat SAT: Fat = medium, Water = bright, silicone = dark
DarkDark silicone with STIR
  • Acquire an axial or sagittal plane
  • Change the TI to 400 to suppress the silicone instead of the fat
Figure 5. STIR with silicon suppressed: Fat = dark, Water = bright, Silicone = dark
BrightDynamic (with and without contrast) or multiphase with Fat SAT or Flex
  • Use VIBRANT with fat SAT(special), VIBRANT Flex, or VIBRANT DISCO
  • Place the center frequency on water for fat SAT
Figure 6. No slicone in breast: Left = VIBRANT with Flex, right = VIBRANT
Silicone implant imaging can be very difficult because with silicone there are three peaks in the manual prescan spectrum, and this can confuse the system during auto prescan because the silicone peak is often the strongest (tallest) peak. Therefore, with most sequences with silicone, you must do manual prescan to make sure prescan is centered on the correct peak to saturate fat, water, or silicone.
Figure 7. Spectra illustrating relationship of water, fat, and silicon peaks
Table 3. Image legend
NumberDescription
1Water
2Fat
3Silicone

Step-by-step instructions

  1. From the GE library, select the desired pulse sequence.
  2. Graphically prescribe the slices.
  3. From the Chem SAT menu, select the appropriate SAT pulse.
    Figure 8. Chemical SAT menu
  4. Click Save Rx.
  5. From the scan menu, select Auto Prescan.
    Figure 9. Scan menu
    • Auto Prescan is performed and it automatically optimizes the transmit gain and receive values for the area of interest.
  6. When Auto Prescan is finished, from the scan menu, select Manual Prescan.
  7. From the manual prescan screen, click Center Frequency Fine to view the peaks.
    1. Slide the Rec bar to the right until it is on the highest receiver.
    Figure 10. Center frequency prescan screen
    NumberDescription
    1Center Frequency Fine
    2Coil receiver value
    3The line in the middle represents AX (actual frequency or where the CF is centered).
    4

    Rec slider allows you to select a coil receiver.

  8. Adjust the center frequency over the appropriate peak, which peak depends on the desired type of suppression. There are two methods in which you can adjust the peaks.
    1. Method 1
      1. Click Center Frequency Coarse (CFL).
      2. From the manual prescan menu bar, select Markers > Vertical Hairline. A thicker vertical line appears next to the center frequency line.
      3. Left click and drag the vertical hairline over the peak you want to suppress.
      4. Click the middle mouse button to apply your selection. This may take a few seconds. Repeat this step if needed to suppress the signal as much as possible.
      5. Once you are satisfied with the center frequency, click Done.
      6. From the scan control area, click Scan.
      Figure 11. Method 1 for center frequency adjusment
      NumberDescription
      1Center Frequency Coarse
      2Vertical Hairline marker selection
      3Center frequency line
      4Vertical Hairline marker
      5Done button accepts changes to the manual prescan screen and closes the screen.
    2. Method 2
    1. Click Center Freq Fine (CFH).
    2. Move the Delta Freq (Dx) slider bar the appropriate number of Hz you want the spectrum to move.
    3. Click Apply to move the delta frequency. This may take a few seconds.
      • Repeat the adjustment of the delta frequency and Apply steps until you are centered on the desired peak.
      • Sometimes the water and fat peaks are not clearly dilineated, particularly when silicone is present. You can still center on the desired peak by centering on the silicone peak, then change the CF offset by moving the Delta Frequency slider to the left, the direction that water and fat sit in relation to silicone.

        1.5T example: To center on water on if the peak is on silicone, move the slider 320 Hz to the left. The maximum the slider moves per action is 200 Hz. Therefore, to move 320 Hz, first move 200 and click Apply, and then move120 and click Apply again)

    4. Once you are satisfied with the center frequency, click Done.
    5. From the scan control area, click Scan.
      Figure 12. Method 2 for center frequency adjustment
    NumberDescription
    1Center Frequency Fine
    2Delta Freq (Dx) Delta frequency slider
    3Apply button applies the frequency set by the Delta Freq (Dx) slider
  9. To suppress silicone, change the center of the water or fat pulse.
    1. Select a protocol that has Fat selected from the Chem SAT menu.
    2. From manual prescan, place the center frequency over the water peak.
      Figure 13. 1 = water peak, 2 = fat peak, 3 = silicone peak
    3. From the manual prescan menu bar, click Options.
    4. From the Options menu, select Modify RSP.
    5. In the RSP text field, type csf.
    6. Change the value in the Current value text field to make the appropriate frequency shift to suppress silicone.
      Figure 14. 1 = water peak, 2 = fat peak, 3 = silicon peak
    7. From the Display RSPs screen, click Accept.
    8. From the Manual Prescan screen, click Done.
    9. From the scan control area, click Scan and enter -320.
      Figure 15. Silicon suppression Display RSPs