The Quantification Tool provides a means to quantify density and activity parameters in CT and NM scans, respectively. The tool provides several options for generating quantification data. There are multiple methods for setting the volume of interest, flexibility in selection of the quantification view direction, easy-to-read presentation of data found in the Quantification Table, and options for saving and loading VOIs or plotting data.
Quantification++ can be accessed via the tool pull-down menu on the IVS front panel.
Upon selection of the Quantification++ Tool, the Quantification Panel appears. The first step in using the quantification tool is the definition of a Volume-of-interest (VOI).
The VOI may be drawn in either the transverse (default), coronal, or sagittal plane. To toggle between these options, use the "View" menu in the Quantification panel.
In this example using the default settings, the axial sliders determine the extent of the VOI in the axial direction. The region or pre-defined shape described below determines the bounds of the VOI in the transverse plane.
By using the "View" pulldown menu, it is also possible to draw VOI boundaries in the sagittal plane:
or coronal plane:
Four VOI types (labeled as Modes) are available.
Spline : Points are defined and smooth curves are drawn in between. The base points can be moved by using the left mouse button to drag them. Additionally, points can be deleted (middle click point) or added (double click position on curve). Once a shape has been closed (right mouse button), it can be re-opened by using Shift + middle click on a point.
Freehand: A freehand region may be drawn by moving the mouse
while holding down the left mouse button. The region may be drawn in
segments through a series of L-clicks.
Bully: Push lines out or into the object with a circle-shaped cursor. The size of the cursor is defined by the Bully Rad field in the quantification table's Options section. This mode provides an efficient way to fine-tune an ROI made in Spline or Freehand mode.
Isocount: A reference voxel is determined with a L-click in the transverse window. The VOI is determined by finding the region of voxels surrounding the reference voxels that share similar values to the reference voxels. The Isocount threshold value establishes how near in value the boundary voxels must be to the reference voxel. VOIs can be rotated by using Shift + the mouse wheel, scaled by using Alt + the mouse wheel, or moved by using Shift + the left mouse button.
Once the desired VOI has been defined, a right-click may be used to fill in an entry in the main table of the Quantification Table. This table contains a wide range of information, as described below. Note that the unit used for measuring CT attenuation is the Hounsfield Unit (HU) while the unit used for measuring activity in the NM scans is Mega-Becquerel (MBq), kilo-Becquerel (kBq), or micro-Curie (uCi). Click the Clear (
) button in the Options section of the quantification table in order to clear the current VOI and begin drawing another.
IVS maintains the most recent VOI until a new VOI is defined. Each VOI for which data is collected is assigned a new color. Note, for example, that editing a VOI following data calculation results in a change to the color of the VOI. Also, the MIP reflects the currently selected VOI by shading the region encompassed by the VOI according to the appropriate color.
After defining the VOI and R-clicking, the quantification table will fill the following fields.
| Field | Description |
| ROI | Field available for comments/ROI names. A L-click in the field will activate and allow comments to be entered. |
| Patient | The patient Name for this particular study. |
| Series | The specific data set in the Study from which this data was calculated. |
| Modality | Displays the modality from which the data values for that row were calculated. |
| Color | The color of the ROI as drawn in the display. |
| Voxels | Total number of voxels contained in the selected VOI. |
| Volume [mm3] | The volume of the selected VOI in units of cubic millimeters. |
| Sum | The total amount of attenuation/activity in the selected VOI for CT and NM data sets, respectively. |
| Unit | Hounsfield units (HU) are used for CT data. The SPECT units used by the Quantification++ panel may be specified in the Data Panel of the Configuration Tool. Options include MBq, kBq, mCi, and µCi. |
| Concentration | The total amount of attenuation/activity in the selected VOI for CT and NM data sets, respectively, divided by the VOI volume. |
| Unit | Hounsfield units (HU/mm^3) are used for CT data. The SPECT units used by the Quantification++ panel may be specified in the Data Panel of the Configuration Tool. Options include MBq/mm3, kBq/mm3, mCi/mm3, and µCi/mm3. |
| Mean | The average amount of attenuation/activity in the selected VOI. |
| StdDev | The standard deviation is a measurement of the variability in attenuation/activity in the selected VOI from voxel-to-voxel. The smaller this value, the more uniform the distribution of attenuation/activity in the VOI. |
| Min | The minimum attenuation/activity value of the voxels in the selected VOI. |
| Max | The maximum attenuation/activity value of the voxels in the selected VOI. |
| ZRange | Specifies via slice numbers the distance spanned by the axial sliders |
The Options menu of the Quantification Panel provides a Cutting option and miscellaneous ROI functions.
| Append modified data | |
| Cut outside ALL | Clears all voxels outside the VOI within the currently selected slices, and all voxels outside the currently selected slices. Slices outside the set axial range will be cleared entirely. |
| Cut | Clears all voxels inside/outside the VOI within the currently selected slices, depending on which direction (inside/outside) is selected. Slices outside the set axial range will not be affected. |
| Apply ROI to all slices | Applies the ROI to every slice in the image. |
| Select FOV | Creates a new ROI entry representing the field-of-view (the entire volume of the image). The quantification table will be populated with this entry, and labelled as 'FOV.' |
It is possible to plot the quantified data. This function is useful to look at changes in activity, concentration, volume, etc., particularly in gated, dynamic, and longitudinal studies.
To plot data from the quantification tool, select the column of interest (i.e., Sum, Mean, etc.), right-click on any element in the column, and select "Plot Data".
The plotted data will open in a new window and may be saved into an output PDF file.
The Quantification++ package also provides several options for saving quantification and VOI information.
| Menu Item | Shortcut | Description |
| Save table | Ctrl+S | Saves the current Quantification table. Accepted formats include .csv, .txt, and .xls. Note: For opening data in Microsoft Excel, save it in .xls format. |
| Append to table | Ctrl+A | Appends the current Quantification table to a previously saved table. |
| Load ROI | Ctrl+Shift+L | Loads a previously saved VOI. |
| Save ROI | Ctrl+Shift+S | Saves the current VOI as a .roi file. |
| Copy table | Ctrl+C | Copies the data in the Quantification table to the clipboard. |
| Clear table | Clears the current Quantification table. | |
| Submit to iPACS | Submit the quantification data as a Data Point to the associated image on the iPACS. | |
| Close | Ctrl+Q | Closes the Quantification panel and returns the IVS to the Navigation screen. |