Empirical Bayesian estimation in graphical analysis: a voxel-based approach for the determination of the volume of distribution in PET studies.
BACKGROUND
Total volume of distribution (V(T)) determined by graphical analysis (GA) of PET data suffers from a noise-dependent bias. Likelihood estimation in GA (LEGA) eliminates this bias at the region of interest (ROI) level, but at voxel noise levels, the variance of estimators is high, yielding noisy images. We hypothesized that incorporating LEGA V(T) estimation in a Bayesian framework would shrink estimators towards prior means, reducing variability and producing meaningful and useful voxel images.


METHODS
Empirical Bayesian estimation in GA (EBEGA) determines prior distributions using a two-step k-means clustering of voxel activity. Results obtained on eight [(11)C]-DASB studies are compared with estimators computed by ROI-based LEGA.


RESULTS
EBEGA reproduces the results obtained by ROI LEGA while providing low-variability V(T) images. Correlation coefficients between average EBEGA V(T) and corresponding ROI LEGA V(T) range from 0.963 to 0.994.


CONCLUSIONS
EBEGA is a fully automatic and general approach that can be applied to voxel-level V(T) image creation and to any modeling strategy to reduce voxel-level estimation variability without prefiltering of the PET data.
Zanderigo
Francesca
F
Department of Molecular Imaging and Neuropathology, New York State Psychiatric Institute, New York, NY, USA. francesca.zanderigo@gmail.com
Ogden
R Todd
RT
Bertoldo
Alessandra
A
Cobelli
Claudio
C
Mann
J John
JJ
Parsey
Ramin V
RV
D001499:Bayes Theorem; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008962:Models, Theoretical; D016011:Normal Distribution; D049268:Positron-Emission Tomography / Q000706:statistics & numerical data*
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