Movement correction method for human brain PET images: application to quantitative analysis of dynamic 18F-FDDNP scans.
Head movement during a PET scan (especially a dynamic scan) can affect both the qualitative and the quantitative aspects of an image, making it difficult to accurately interpret the results. The primary objective of this study was to develop a retrospective image-based movement correction (MC) method and evaluate its implementation on dynamic 2-(1-{6-[(2-(18)F-fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile ((18)F-FDDNP) PET images of cognitively intact controls and patients with Alzheimer's disease (AD).


METHODS
Dynamic (18)F-FDDNP PET images, used for in vivo imaging of beta-amyloid plaques and neurofibrillary tangles, were obtained from 12 AD patients and 9 age-matched controls. For each study, a transmission scan was first acquired for attenuation correction. An accurate retrospective MC method that corrected for transmission-emission and emission-emission misalignments was applied to all studies. No restriction was assumed for zero movement between the transmission scan and the first emission scan. Logan analysis, with the cerebellum as the reference region, was used to estimate various regional distribution volume ratio (DVR) values in the brain before and after MC. Discriminant analysis was used to build a predictive model for group membership, using data with and without MC.


RESULTS
MC improved the image quality and quantitative values in (18)F-FDDNP PET images. In this subject population, no significant difference in DVR value was observed in the medial temporal (MTL) region of controls and patients with AD before MC. However, after MC, significant differences in DVR values in the frontal, parietal, posterior cingulate, MTL, lateral temporal (LTL), and global regions were seen between the 2 groups (P < 0.05). In controls and patients with AD, the variability of regional DVR values (as measured by the coefficient of variation) decreased on average by more than 18% after MC. Mean DVR separation between controls and patients with AD was higher in frontal, MTL, LTL, and global regions after MC. Group classification by discriminant analysis based on (18)F-FDDNP DVR values was markedly improved after MC.


CONCLUSIONS
The streamlined and easy-to-use MC method presented in this work significantly improves the image quality and the measured tracer kinetics of (18)F-FDDNP PET images. The proposed MC method has the potential to be applied to PET studies on patients having other disorders (e.g., Down syndrome and Parkinson's disease) and to brain PET scans with other molecular imaging probes.
Wardak
Mirwais
M
Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California 90095-6948, USA. mwardak@mednet.ucla.edu
Wong
Koon-Pong
KP
Shao
Weber
W
Dahlbom
Magnus
M
Kepe
Vladimir
V
Satyamurthy
Nagichettiar
N
Small
Gary W
GW
Barrio
Jorge R
JR
Huang
Sung-Cheng
SC
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000000981:diagnostic imaging; D001921:Brain / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D005260:Female; D005462:Fluorine Radioisotopes; D019416:Head Movements; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D009570:Nitriles; D049268:Positron-Emission Tomography / Q000706:statistics & numerical data*; D019275:Radiopharmaceuticals; D012189:Retrospective Studies
C444520:2-(1-(6-((2-fluoroethyl)(methyl)amino)-2-naphthyl)ethylidene)malononitrile; D005462:Fluorine Radioisotopes; D009570:Nitriles; D019275:Radiopharmaceuticals