I am using slicer to measure volume of the brain. I typically trace the area I want with draw effect and fill it. I do same thing slide by slide until the whole volume I am interested in is filled. I then use label statistic to get the volume. The program gives me volume and standard deviation. Can anyone please explain what the standard deviation means? I noticed with some measurements I got larger standard deviations than others. What can I do to improve my method and get a more accurate/precise measurements? Thanks
First, I’d suggest that you use Segment Editor for segmentation, which has a Fill between slices tool that allows you to skip slices and then automatically fill the gaps in - this would fit your workflow and speed it up (and also the Editor module will be removed in 5.0).
Then you can use Segment Statistics to calculate the volume.
Standard deviation is about the voxel intensities not the volume. The volume is an exact measurement.
So I am trying to use segment editor like you suggested, but as I filled a slide on axial, slides above and below were also filled. What happened if I do not want to include slides below and above?
Also, when I use fill between slides, there seem to be gaps. Will it affect my volume measurement? Thanks.
You only fill one slice by default. Based on your screenshot your volume is not axis-aligned. You need to rotate the slice plane so that it aligns with your volume.
Yes, what you see is a feature: Slicer’s Segment Editor module allows editing on arbitrarily oriented views, which may intersect multiple slices.
Recent versions of Slicer show a warning button (with an exclamation mark) if any of the slice viewers are not aligned with the current segmentation axes. Click that button to snap each slice view to nearest segmentation axis.
If “Fill between slices” effect finds segments on consecutive slices then it considers them already 3D (already filled). So, you need to work with axis-aligned slice viewers and skip at least one slice between segmented slices.
Volume is reported for exactly what you see. If you see that segmentation is incomplete/inaccurate then you need to fix that before you compute volume.
I am not sure why, but slicer is not showing me full view of these two slides and on the other view, I can’t roll between views like how we normally view CT scans. I randomly got it work one time and I could not get it worked again…Please help!!! Thanks…
Have you loaded your data set using DICOM module (using the DICOM browser that shows patient, study, series list)?
You may have several image series in a study and some of them may be single-slice, so make sure you choose a volumetric image. You can load all series in a study then go to Data module and click on eye icons to choose which one you would like to see.
Yes I used DICOM. I pick patient then the views that have acquisition number to load. Normally it will just load images in three views sagital, coronal and axial. I am not sure what is wrong with this disc (I have not experienced this problem before), like you said some study may be single slice, but I got it to work on same disc, but I can’t get it to work again unfortunately.
From this screenshot it is not obvious if any of these are volumetric acquisitions. You can verify if there are multiple frames in a series by clicking “Metadata” button: if there is a slider near the top of the window then it confirms that the series contains multiple frames.
Did you select a single series when you got this slider? If yes, then it is a volume and if you click “Load” then you should see a volume (a full image in all three orthogonal slice viewers).
Why are there color outside the skull? I do not understand how fill in between works so I just want to make sure I get as accurate results as possible.
