In the clinical application of activation PET studies with 15O-water, optimal PET images are required when the high activity of a nearby lesion might affect the activated area.
Methods: To determine the optimal time for data acquisition of PET images, we performed serial dynamic PET measurements in five patients with cerebral arteriovenous malformation (AVM). All AVMs were closest to the motor cortices, and the activation task was opponent finger movement contralateral to the AVM. Activation PET and MR images were coregisterated for localization of activated foci.
Results: Time-activity curves of the nidus and normal cortex from the dynamic PET data demonstrated a discrepancy in peak time and significant radioactivity increase in the nidus during the early phase. Elimination of the initial PET data provided better contrast in activated foci without affecting the calculated cerebral blood flow of other areas.
Conclusion: Delayed data acquisition can avoid interference of the AVM nidus with the activated area.