Derivation of input function from FDG-PET studies in small hearts.
The extraction of pure arterial time-activity curves (TACs) from dynamic PET images of a small animal heart using factor analysis of dynamic structures (FADS) was found to be unsuccessful due to the small size of the cardiac chamber that causes extensive mixture of TACs of different structures.


METHODS
In this study, we used digital phantoms of the left ventricle (LV cavity size: 1-2 cm) and small monkey (LV cavity size: approximately 2 cm) dynamic FDG PET studies to evaluate FADS for extracting the pure blood-pool TACs by adding a single blood sample (taken at a late scan time) constraint.


RESULTS
In the digital phantom studies, spillover fractions in the extracted blood-pool TACs using FADS without a blood sample constraint (FADS(-)) and with a blood sample constraint (FADS(+)) were 3%-91% and < 3%, respectively. In the monkey studies (n = 4), FADS(+) extracted blood-pool TACs matched well with the arterialized well counter measurements (% differences of curve integration; FADS(-) < 82%; FADS(+) < 9%). The microparameters (K1*, k2*, k3*, k4*) and macroparameters (Knlr), obtained from the FADS(+) blood-pool TACs, were similar to those obtained from plasma samples in a three-compartment model fitting (% differences of Knlr:phantom studies < 5%; monkey studies < 9%).


CONCLUSIONS
The FADS technique with a single-blood sample has the potential to extract the pure blood-pool TACs directly from dynamic PET images of a small animal without multiple blood sampling, region of interest definition or spillover correction.
Wu
H M
HM
Department of Molecular and Medical Pharmacology, University of California at Los Angeles, School of Medicine 90095-6948, USA.
Huang
S C
SC
Allada
V
V
Wolfenden
P J
PJ
Schelbert
H R
HR
Phelps
M E
ME
Hoh
C K
CK
D000818:Animals; D003198:Computer Simulation; D003847:Deoxyglucose / Q000031:analogs & derivatives*; D005260:Female; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D000882:Haplorhini; D006321:Heart / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D008297:Male; D014055:Tomography, Emission-Computed
D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D003847:Deoxyglucose