RT Journal Article SR Electronic T1 Effects of body activity on brain PET quantitative capability in the early phase of 11C-PiB dynamic scans JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 2076 OP 2076 VO 52 IS supplement 1 A1 Tomoyuki Nishio A1 Yasuhiko Ikari A1 Keiji Shimizu A1 Hidehito Nagai A1 Michio Senda YR 2011 UL http://jnm.snmjournals.org/content/52/supplement_1/2076.abstract AB 2076 Objectives Kinetic analysis of PiB dynamic scan including early phase as well as late phase images provides more accurate quantitative information of amyloid deposition than the late phase alone. Random and scatter coincidence events from body activity may degrade quality and quantitative capability of brain PET images, especially in the early phase of 3D scans when high activity is in the body, although the detailed whole-body (WB) activity distribution and time course have not been measured in detail. This study measured WB distribution of 11C-PiB in the early phase and evaluated the effect of body activity on the 11C-PiB brain PET images. Methods PET was performed with ECAT EXACT HR+ scanner (CTI/Siemens). To survey biodistributions of the activity for each organ over time, a 40-minute WB dynamic scan or a 90-minute brain dynamic scan was acquired starting 11C-PiB injection (555±185 MBq). The effect of body activity was evaluated using a cylindrical phantom in a 3D mode with relevant activity placed outside the FOV to simulate 11C-PiB biodistribution at 2-3 minutes after the injection. Results At 0-6 min post injection, 11C-PiB was distributed in lungs (13.2 % injected dose), liver (10.3 %), heart (2.6 %), spleen (1.3 %) and kidneys (5.2 %). The 11C-PiB brain time course showed a peak 6-7 % injected dose around 2 minutes post injection. The phantom experiment indicated that the brain activity was underestimated by 5.6 % in the caudal slices covering cerebellum and overestimated by 5.8 % in the cranial slices. Conclusions This study suggested effects of body activity on brain PET images in the early phase of 11C-PiB PET data, which may affect the DVR estimation depending on the kinetic analysis method