If a dynamic series has been loaded and VOIs are defined, the becomes active, it the PKIN option is included in the PMOD license. At allows calculating the TACs and transferring them directly to the PKIN tool.
A dialog window appears which is organized in four areas:
The following options are supported
Averaged VOI TAC
The standard and default procedure is to transfer the signal average in the VOIs, corresponding to the radio button Averaged VOI TAC. In addition to the average the standard deviation is also calculated and transferred as it is potentially useful for weighted fitting in PKIN.
Instead of transferring the average signal per VOI, the individual TACs of the voxels enclosed in the VOIs can be transferred. This behavior is set by the TAC of each VOI voxel button. For performance reason there is a maximum number of TACs which will be considered for the transfer, per default set to 10'000. The number of voxels in the selected VOIs is shown in brackets in the control section. Naturally, the standard deviation is zero in this case.
TAC Value Operations
The calculated TAC values can be modified in two ways.
TAC Time Shifting
If image data acquisition requires multiple table positions (e.g. dynamic whole-body PET), the timing between VOIs may differ. The timing relative to the injection is crucial for modeling and also for dosimetry. Therefore, the Delay by VOI location option is supported
with three alternatives:
Note that the timing derived from these settings can only be approximate and may need correction. The resulting timing of the TAC curves is updated in the curve window whenever one of the settings is changed. Depending on the scanning, the time shifts may be applied in the wrong direction. For instance, the bladder curve may start before the brain curve although the data was acquired in head-in position. To rectify such a case there is a switch Time increases with slice number/Time decreases with slice number. For Averaged VOI TAC transfer, the timing of the VOI center will be used.
The Model Selection option allows filtering the list of the PKIN models according to the intended modeling. For the Dosimetry model the Cumulated Activity (OLINDA, IDAC) model will be set after the TAC data have been transferred to the PKIN tool together with the Total body mass of the subject. This information is extracted from the demographic information in the image, and can be edited if it is not present.
If the Decay correction to Injection time flag allows correcting the TACs to a n injection time which may be before the first acquisition. If the Source data is decay corrected, only a scaling factor is applied. Otherwise, a time-dependent correction is used.
The Send buttons initiates the transfer of the activity curve data to the PKIN tool. Selecting Send TACs to PKIN [Current workspace] transfers the TACs to the currently selected tab in an open PKIN tool. With the Append TAC Data box checked, the curves are appended as new regions to the existing data, otherwise the current data is over-written. SendTACs to PKIN [New workspace] first creates a new tab in PKIN, to which the data is added. If PKIN is not running, the tool is first started and the data added.
In addition to the TACs, subject and study related information is also transferred.