Small Animal Imaging Resource Program @ Johns Hopkins


Creating a mean image

For dynamic PET studies it is often useful to create a mean image. For example, a mean PET image may be used for coregistration with MR, or to create a reference image for motion correction.

Using Analyze
Creating a mean image

X = number of time frames
Y = number of slices

  1. Go to File/Load As
  2. Choose the file header (‘.hdr’ file)
  3. Choose “Calculate It” when prompted for Max/Min Values
  4. Click on Load
  5. Select Single Big Volume
  6. Open Process/Image Algebra, select “Forget parameter”
  7. Type in “ADDAVG(X, Y)”
  8. Drag the desired volume from the workspace into the box under Variables with the title “ADDAVG(X, Y)”
  9. Right click on the Input (the image ADDAVG(X,Y) in the Variables) and select parameters
  10. Volume: Start at 1, Increment by 0, Number is All
  11. Slice: Start at 1, Increment by 1, Number is specified to Y
  12. Click on “Done”
  13. Right click on Output and select parameters
  14. Choose Disk to save the image
  15. Enter the desired directory in the “DIR” box
  16. Enter the desired filename next in the  “File” box
  17. Volume: Start at 1, Increment by 0 (Should not need to choose Number)
  18. Slice: Start at 1, Increment by 1, Number specified to Y
  19. DataType: Float, Max/Min Settings: Calculate
  20. Click on “Done”
  21. Click on “Go” in the main Image Algebra Screen
  22. When completed, drag the output to the workspace to get the mean image.

Reslicing the mean image to create a sagittal view

  1. Select the mean image in the main Analyze 7.0 window
  2. File-> save as
  3. In ‘Save as’ window, Select Orient-> Sagittal, Resize -> select ‘Force Cubic’
  4. Give an unique file name and save