• Object ID: 00000018WIA30348970GYZ
  • Topic ID: id_40022579 Version: 1.3
  • Date: Jul 3, 2022 5:47:12 PM

BrainStat AIF Optional procedure

About this task

To change BrainStat settings, make a selection from the desired BrainStat AIF screens.

Step-by-step instructions

  1. From the BrainStat AIF screen, click and drag the left threshold slider until the brain is outlined in green and all the anatomy inside the image displays green lines. This indicates that all the anatomy inside the brain is used for the map calculations and the noise outside the brain is not used.
    The BrainStat AIF algorithm automatically determines a noise mask to exclude pixels from the map computation. This may be higher than the default lower processing threshold setting, therefore it may initially appear that adjusting the lower threshold has no effect on the maps. The maps are only affected by the lower threshold if it is set higher than the automatic mask threshold computed by the algorithm.
    Note: Compute does not update the threshold. As the upper or lower slider is moved or a value entered in the text box, the threshold automatically updates.
  2. From the BrainStat AIF screen, click the preprocessing arrow and click Motion Correction if the images exhibit distortions with respect to the reference image.
    • Use the Scoll Image icon () on the Review Controller to review all the input images for motion artifact or incorrect geometry before processing.
    • Use Motion Correction to minimize the effects of patient motion.
    • To save the new set of processed images so that you can access the corrected series repeatedly, click Quick Export on the export toolbar.
  3. From the BrainState AIF screen, click the AIF mode arrow and click one of the processing modes.
    • Ensure recomputation of maps after modification of input parameters.
    • Ensure that you review and if necessary correct the position and signal characteristics of detected vessels in automatic and semi-automatic mode before reviewing the computed functional maps. Switch to a different vessel detection mode if results are not optimal.
    • Auto is the default option. It automatically selects pixels based on the temporal form of the signal. After AIF pixels have been determined, all pixel values are averaged and a final AIF curve displays.
    • Click Semi-Autoto search for arteries within a user defined ROI.
      1. From the Measure/Annotate toolbar, click an ROI tool.
      2. Click the image to deposit the ROI.
      3. Position and shape the ROI. For details, see Modify measurements.
      4. From the AIF Mode selection area, click Search to activate the detection of arteries within the ROI.
      5. Click Compute to update the maps.
    • Click Manual to define one single-pixel artery. From the Manual AIF mode area, complete the following:
      • Click the Pixel ROI icon ().
      • Left-click in the area of interest to deposit the pixel ROI.
      • Click Compute.
    • Be sure to place manual vessel pixels in appropriate areas of the image based on anatomy and signal characteristics.
    • Auto, Semi-auto and Manual arteries can be deleted by selecting the individual artery and pressing Delete. Alternatively, right-click a vessel and select Delete or Delete All from the menu.
  4. From the BrainStat AIF screen, click the vessel exclusion arrow and click and drag the slider to remove pixels with high relative CBV values as defined by BrainStat AIF's auto window width and level setting algorithm. The maps update as you adjust the slider.
    • Allows dynamic adjustment of the vessel exclusion level. The vessel removal algorithm helps to remove vessel pixel contribution when ROI are placed over brain parenchyma to measure brain perfusion characteristics in gray matter
    • A CBV brain mask is obtained and applied to all parametric maps (CBF, MTT, etc.) and the masked pixels are excluded from any ROI measurement.
  5. From the Clip Min & Max screen, complete the following steps.
    1. From the menu, select the map you want to modify.
    2. Click and drag the slider and watch the selected map update in real-time.
    3. If desired, segment the pixels: place the cursor in the map you clipped and right-click Convert to ROI. This automatically updates the time-intensity curve.
  6. From the BrainStat AIF screen title bar, click the Tools icon ().
  7. From the BrainStat AIF screen, click the arrow next to BrainStat - Advanced Settings arrow to change the physiological parameters or Kernel Spatial Smoothing.
    • Ensure recomputation of maps after modification of input parameters.
    • If needed, type a new value for the physiological parameters.
    • As the kernel size increases, voxel averaging occurs and the image maps appear smoother. The Kernel spatial smoothing default value is 0
      1. Change the desired settings.
      2. Click Compute to generate updated maps.
        • Reset changes the selections to the factory default values.
        • Save All saves your selections as the new default values.
  8. From the BrainStat AIF screen, click the BrainStat - Final Settings arrow and review the settings. If you want to change any of the settings, click the appropriate selection from the BrainStat AIF screen. Click Compute to generate an updated map.
  9. To view leakage indicator for functional curves, complete these steps.
    1. From the Review steps, click the rCBV, rCBF, Leakage tab ().
    2. Place the cursor in the graph viewport and right-click to display the Graph Curves Selection screen.
    3. From the Graph Curves Selection screen, click the Reconvolved Signal option button, which displays either a T1 or a T2* effect graph and map.
      Figure 1. Graph Curves Selection screen
      Figure 2. T2* Leakage Indicator graph and map
      Table 1. Image legend
      NumberDescription
      1T2* Leakage Indicator graph shows where the post-bolus stays below the baseline level.
      2T2* Leakage Indicator map.
      Figure 3. T1 Leakage Indicator graph and map
      Table 2. Image legend
      NumberDescription
      1T1 Leakage Indicator graph shows where the post-bolus curve crosses above the baseline level.
      2T1 Leakage Indicator map.
  10. To exit READY View, click the Exit icon ().