RT Journal Article SR Electronic T1 Comparison of longitudinal [11C]PiB change measures and impact of CSF dilution correction JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 2028 OP 2028 VO 52 IS supplement 1 A1 Brian Lopresti A1 Chester Mathis A1 Ann Cohen A1 Rhaven Coleman A1 William Klunk A1 Julie Price YR 2011 UL http://jnm.snmjournals.org/content/52/supplement_1/2028.abstract AB 2028 Objectives Longitudinal amyloid imaging requires detection of small retention changes at typical follow-ups of 12-36 mos. Simplified retention measures improve longitudinal study feasibility but differ in terms of bias/variability [1]. This work compares simplified PiB longitudinal change measures and examines the impact of atrophy-related CSF dilution in Alzheimer's disease (AD), mild cognitive impairment (MCI), and cognitively normal (CN) subjects. Methods [11C]PiB PET scans (no blood sampling) were performed at baseline for 7 AD (72±12 yrs; MMSE: 21±5), 12 MCI (71±7 yrs; MMSE: 28±1) and 29 CN (73±10 yrs; MMSE: 29±1) subjects, with follow-up at 28±10 mos. MR imaging guided region (ROI) definition and CSF correction (CSFc) for anterior cingulate (ACG), precuneus (PRC), a 4-ROI cortical mean (CTX4: ACG/PRC/Frontal/Parietal), and cerebellum (reference). The 40-60min SUVR and 40-90min reference Logan DVRcer measures were compared. PiB(+/-) amyloid status was based on an outlier method [2]. Longitudinal change was computed in SUVR or DVR units. Results CSFc factors were similar at follow-up for MCI and NC groups, while decreases were found in some AD brain areas (ACG p<0.01; CTX4 p=0.02) but not others, PRC (p=0.15). Before CSFc, annual retention increases were apparent for 14 PiB(+) CNs but greatest for 8 PiB(+) MCIs (ACG 0.17±0.23 SUVR/yr), relative to no change in 15 PiB(-) CNs (ACG 0.02±0.03 SUVR/yr). Retention was fairly unchanged for 7 PiB(+) ADs with small decreases evident in ACG (-0.04±0.07 SUVR/yr). After CSFc, AD retention changes were generally positive (ACG 0.06±0.16 SUVR/yr); 1 AD exhibited large CSFc and MMSE changes. Results were similar for DVRcer. MCI and CN results were similar before and after CSFc. Conclusions Longitudinal results were fairly consistent across groups for the simplified measures examined. Increases in atrophy-related CSF dilution over the follow-up period may confound amyloid load change assessments, particularly for AD subjects. [1]Lopresti JNM 2005; [2] Aizenstein Arch Neurol 2008 Research Support NIH;Dana Foundation;Alz. Associatio