Selecting specific connected components in 3D image stack and display them

Hi,

I am trying to select certain connected components from an image stack. I am a bit confused about the proper indexing method to do this. The relevant part of the code is the following:

CC = bwconncomp(Stack,26); % calculate the connected component in Stack, which is a 500 x 500 x 500 array

stats = regionprops3(CC,'VoxelIdxList','Volume','SurfaceArea','EquivDiameter'); %measure the properties of the connected components;

stats.Sphericity = ((6*stats.Volume).^(2/3))*((pi).^(1/3))./stats.SurfaceArea; % I'm calculating the sphericity here as I need it to differentiate the objects;

Idx = [stats.Sphericity] < 0.8; % I'd like to show in the image stack only the connected components with a sphericity lower than 0.8;

How do I set the voxels in Stack such that only the objects with sphericity lower than 0.8 are displayed? I've tried using the synthax used in other examples with 2D images, but it returns the following error: Requested array exceeds the maximum possible variable size.

Thanks! hope the question is clear.