Modeling Results

This section contains some options with respect to the modeling results:

• SDV unit: The kinetic model not only returns the fitted parameter values, but also estimates of their standard error. The standard error can be expressed in absolute units (1/1 configuration), or in percent of the parameter value (% configuration, coefficient of variation).
• Myocardium half width of volume showing the active parameter values: The cardiac tool constructs a new image data set which shows the calculated parameter value (usually the MBF) in the pixels which were used for calculating the segmental TACs. Usually, these will be pixels along the myocardium centerline, resulting in images showing segments that are much thinner than the myocardium itself. To make the segments looking thicker, pixels on both sides of the centerline can be added. For example a value of 2 would add two pixels to the inner and to the outer of the centerline. Images with increased segment thickness may be an advantage for fusion purposes, especially for a 3D fusion with an angio CT data set.
• Add Chi^2 map to results: When this box is checked the Chi square value of the kinetic model fit is also returned to PCARD and assembled in an additional polar map.
• Compare Type: When a patient has been scanned at rest and stress, the results can be compared in two ways. With the RESERVE (S/R) choice the perfusion reserve is calculated by dividing the segmental (perfusion) values at stress by the corresponding values at rest. With the DIFFERENCE (S-R) choice the (perfusion) difference is calculated instead. This latter approach avoids the problem of dividing by a small number which may for instance arise in scar tissue.