Statistics Measures

Except for the Pixel Dump different levels of statistics can be collected:

Statistics: Standard descriptive statistics measures.
Peak Statistics: The standard descriptive statistics evaluated in a sphere located at the maximum pixel in the VOI.
Statistics + Surface + Sphericity: Standard descriptive statistics measures, a VOI surface estimate and an index of how sphere-shaped the VOI is.
Statistics + Surface + Sphericity + Diameter: As above, plus the maximum VOI diameter.

The selected statistic type is calculated for each VOI.

Statistics Measures

The following basic descriptive statistics are calculated using the distribution of all pixel values in a VOI:

Averaged	Average of the pixel values.
Sd	Standard deviation of the pixel values.
Volume	Volume of the VOI pixels. It is based on the pixel size in x and y and the slice thickness in z.
Total(SUM)	Sum of the pixel values. The interpretation depends on the image contents. In the case of activity units the result will be total activity in the VOI.
*Total(AVRVOL)**	Average of the pixel values multiplied by the VOI volume. The interpretation depends on the image contents. In the case of activity concentration units, the result represents total activity in the VOI. In the case of SUV units, the result is called Total Lesion Glycolysis (TLG). The TLG is usually calculated in combination with a lower range.
Min	Minimum pixel value.
Max	Maximum pixel value.
NumberOfPixels	Number of pixels included in the VOI.
HotAveraged	The highest pixel values averaged. The default Number of Hottest Pixels values to be averaged can be set in the User configuration, and can be changed in the upper part of the statistics window.
Median	Median value of the VOI pixel values.
AreaUnderCurve	Static data: Averaged times frame duration. Dynamic data: Integral of the Averaged curve.

Additional Measures

The following additional VOI measures can be obtained with the corresponding statistics button:

SurfaceArea	Estimate of the VOI surface which is obtained by triangulating the contours and accumulating the triangle areas.
Spericity	Index of how spherical a VOI is. The values range between 0 and 1 (perfect sphere). Wikipedia
DiameterMax	Maximal distance between any two pixels in the VOI. The calculation can take substantial time and is restricted to VOIs enclosing less than 100'000 pixels.