Module: Material Statistics ()

Description:

This module takes a uniform or stacked Label Field as well as an optional scalar field as input and computes some statistical quantities for the regions defined in the label image.

If the quantities are computed per material or per connected component, the different columns of the spreadsheet have the following meaning:

If an additional scalar field is connected to the module, then five more columns will be generated:

The scalar field will be evaluated at the center of each voxel.

Press the Apply button to start the computation.

Connections:

Data [required]
Label field defining the regions.

Field [optional]
Optional scalar field, for example the image data the label image is associated with. If the scalar field has the same dimensions as the label image, the voxels are accessed directly. Otherwise, a lookup using the field's native interpolation method is performed.

Voi [optional]
Optional label image used as a volume of interest. It is only used if the statistics are set to Volume per VOI.

Ports:

Select

The quantities can be computed in different modes:

The results are stored in a Spreadsheet object.

For example, you may have two separate objects both assigned to the same material. In the Material mode, the two objects will be interpreted as one object, in the Region mode as two objects.

In mode Volume per slice the slices are stored as rows in the spreadsheet. The columns are labeled by the materials and the cells contain the volume of these materials in each slice. The scalar field is ignored. The same output is produced by the Area per slice mode. In both cases the voxel size is used to calculate the value. Because of this, the area value corresponds to the volume value when multiplied by the voxel size in the z-direction.

In mode Volume per VOI (Volume of Interest) another label image must be attached to the connection named Voi. The rows of the spreadsheet are labeled with the materials in this label image. The columns are labeled with the materials of the main label image. For each voxel of the main label field it is determined to which VOI region the voxel center belongs to. The voxel volume is then added to the particular row of the spreadsheet. If the voxel center is outside of the bounding box of the VOI, it is ignored.

In mode Polar moment of inertia the moment of inertia about the z axis is computed which describes the ability of the per-slice cross section to bend. The larger the moment of inertia, the less the section will bend. Additional values that are computed are the center of mass and the area- and mass-radius of gyration about the z axis (,). If the optional scalar field is connected, the real center of mass will be used, otherwise all voxels are assumed to count equally (mass = 1.0). The user may also provide a center of rotation which will be shared for all slices. In the mode Statistics per slice per Label, the mean gray value, the standard deviation, the number of voxels and the min and max values for each label are computed in each slice of the data set. This option requires a scalar field to be connected to the Field port. Only then this option will be visible. The result is a spreadsheet where each row represents a single slice and each column a label in the label field. If a label is not present in a certain slice, 'nan' will be output at the respective entry of the spreadsheet.

Pixels

This port will only be visible if Volume per slice or Area per slice is selected in the Select port. It allows you to exclude small regions from the statistics.

Options

This port will only be visible if Polar moment of inertia is selected in the Select port. It allows you to specify if the center of mass should be automatically detected.

Center

This port will only be visible if detect center of mass is unchecked in the Options port. It allows you to specify the center of rotation.