Using Workbench Command

FILTER CLUSTERS BY VOLUME
   wb_command -volume-find-clusters
      <volume-in> - the input volume
      <value-threshold> - threshold for data values
      <minimum-volume> - threshold for cluster volume, in mm^3
      <volume-out> - output - the output volume

      [-less-than] - find values less than <value-threshold>, rather than
         greater

      [-roi] - select a region of interest
         <roi-volume> - the roi, as a volume file

      [-subvolume] - select a single subvolume
         <subvol> - the subvolume number or name

      [-size-ratio] - ignore clusters smaller than a given fraction of the
         largest cluster in map
         <ratio> - fraction of the largest cluster's volume

      [-distance] - ignore clusters further than a given distance from the
         largest cluster
         <distance> - how far from the largest cluster a cluster can be, edge
            to edge, in mm

      [-start] - start labeling clusters from a value other than 1
         <startval> - the value to give the first cluster found

      Outputs a volume with nonzero integers for all voxels within a large
      enough cluster, and zeros elsewhere.  The integers denote cluster
      membership (by default, first cluster found will use value 1, second
      cluster 2, etc).  Cluster values are not reused across frames of the
      output, but instead keep counting up.  By default, values greater than
      <value-threshold> are considered to be in a cluster, use -less-than to
      test for values less than the threshold.  To apply this as a mask to the
      data, or to do more complicated thresholding, see -volume-math.