The effect of mouth motion on the attenuation correction in neurological PET studies

In each newgeneration of PET scanners, the axial field-of-view(FOV) has been increased as a way to improve their sensitivity and obtain better images, faster and with lower injected doses. Nevertheless, in neurological studies, the use of larger axial FOV can introduce errors in the PET attenuation correction (AC), as possible movements of the patient’s mouth are not currently considered. This effect happens when oblique PET sinograms containing both the jaw and the brain are used. In this work we have studied the bias that mouth motion can introduce in the PET AC, for two different scanners. The average effect over large regions in the brain is around 1% for a moderate mouth motion, although some voxels show differences of up to 18%. These results indicate that if scanners with large axial FOV and acceptance angles are going to be used in the future, possible movements of patient’s mouth should be considered in the AC procedure.