Recipe for creating rotating Maximum-Intensity-Projections (MIPs)
with ImageJ
The description below covers the case of a single 3D data set. Dynamic scans require a
more elaborate processing. The easiest option for producing a time-varying rotating MIP
from a dynamic PET image is to use the Vista software.
Step 1. Load the stack of 3D image data into ImageJ.
Step 2. Reslice the image stack from axial into coronal slices and (simultaneously)
correct the aspect ratio: go to Image/Stacks and select “Reslice” as shown in Fig. 1.
Fig. 1
Selection of “Reslice” option.
Fig. 2 The “Reslice” Window.
In the “Reslice” window, shown in Fig. 2, enter 2.0 for the input Z spacing width and 1.0
for the output slice width if you are dealing with a Vista PET image in which the axial
slice width is 2x the transverse pixel width. For other modalities, aspect ratios are
generally different and require different settings, e.g. CT images have an aspect ratio of
1:1. Further, for “Start At:” select “Top” and check the “Flip vertically” box if necessary.
After clicking OK you will get a stack of coronal slices with the (hopefully) correct
aspect ratio.
Step 3. Adjust maximum brightness for the image to the desired level and convert to 8bit format (from 32-bits). To do this, select the stack with the coronal slices, go to the
Menu Bar and find the “Type” entry under “Image” where you must select “8-bit” to start
the conversion.
Step 4. Finally, go to the 3D-Projection menu which is located under Image/Stacks, as
shown in Fig. 3. In the “3D-Projection” window (Fig. 4), select “Brightest Point” and Yaxis. For the rotation angle, 10 degrees is a good choice and so is the default value of
50% for the interior depth-cueing (bottom of menu). Sometimes, a value smaller than
50% for the depth-cueing produces better looking results.
Fig. 3 Selecting the 3D-Projection Menu
Fig. 4 Options under 3D-Projection.
Step. 5 Finally save the reprojected image as .avi file (see Fig. 5)
Fig. 5 Save reprojected image stack as AVI file.