Variable Timing of Slices

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Variable Timing of Slices

The standard models in PXMOD assume that all slices have the same timing because they were acquired with the scanner field-of-view at a fixed location. Modern PET scanners, however, are introducing dynamic whole-body acquisition functionality. Hereby, the scanner FOV is dynamically moved over the relevant parts of the body during an acquisition. Consequently, the signal is only measured partially for each slice in the volume with temporal gaps when the scanner is not positioned over the slice. This is reflected in the timing of signal, which is unique for each slice. For proper modeling, the slice-dependent acquisition times have to be retrieved correctly from the data, and taken care of in the parametric mapping.

Models which have been prepared to handle slice-dependent timing have an indication Model handles slice-wise timing indication as illustrated below. The Zero time at administration checkbox indicates whether the time scale should be relative to the administration time recorded in the image header, or relative to the acquisition. In the example below, dynamic scanning was indeed only started 6.5min after the injection (because the initial part of the blood activity was measured in a stationary position over the descending aorta). Note, that if available an appropriate time is extracted from the Radiopharmaceutical Start DateTime (0018,1078) information. For GE data, the private field (0009,103B) is used.


Note: Please inspect the times by activating the indicated button and make sure that the timing is correct.