Minimally invasive input function for 2-18F-fluoro-A-85380 brain PET studies.
OBJECTIVE
Quantitative neuroreceptor positron emission tomography (PET) studies often require arterial cannulation to measure input function. While population-based input function (PBIF) would be a less invasive alternative, it has only rarely been used in conjunction with neuroreceptor PET tracers. The aims of this study were (1) to validate the use of PBIF for 2-(18)F-fluoro-A-85380, a tracer for nicotinic receptors; (2) to compare the accuracy of measures obtained via PBIF to those obtained via blood-scaled image-derived input function (IDIF) from carotid arteries; and (3) to explore the possibility of using venous instead of arterial samples for both PBIF and IDIF.


METHODS
Ten healthy volunteers underwent a dynamic 2-(18)F-fluoro-A-85380 brain PET scan with arterial and, in seven subjects, concurrent venous serial blood sampling. PBIF was obtained by averaging the normalized metabolite-corrected arterial input function and subsequently scaling each curve with individual blood samples. IDIF was obtained from the carotid arteries using a blood-scaling method. Estimated Logan distribution volume (V(T)) values were compared to the reference values obtained from arterial cannulation.


RESULTS
For all subjects, PBIF curves scaled with arterial samples were similar in shape and magnitude to the reference arterial input function. The Logan V(T) ratio was 1.00 ± 0.05; all subjects had an estimation error <10%. IDIF gave slightly less accurate results (V(T) ratio 1.03 ± 0.07; eight of ten subjects had an error <10%). PBIF scaled with venous samples yielded inaccurate results (V(T) ratio 1.13 ± 0.13; only three of seven subjects had an error <10%). Due to arteriovenous differences at early time points, IDIF could not be calculated using venous samples.


CONCLUSIONS
PBIF scaled with arterial samples accurately estimates Logan V(T) for 2-(18)F-fluoro-A-85380. Results obtained with PBIF were slightly better than those obtained with IDIF. Due to arteriovenous concentration differences, venous samples cannot be substituted for arterial samples.
Molecular Imaging Branch, National Institute of Mental Health, NIH, 10 Center Drive, MSC-1026, Bethesda, MD, 20892-2035, USA, zanottifregonp@mail.nih.gov.
Paolo
P
Zanotti-Fregonara
Renaud
R
Maroy
Marie-Anne
MA
Peyronneau
Régine
R
Trebossen
Michel
M
Bottlaender
D000328:Adult; D019540:Area Under Curve; D001384:Azetidines; D001921:Brain / Q000098:blood supply / Q000000981:diagnostic imaging*; D002339:Carotid Arteries / Q000000981:diagnostic imaging; D006801:Humans; D007700:Kinetics; D008297:Male; D049268:Positron-Emission Tomography / Q000379:methods*; D011725:Pyridines; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014680:Veins / Q000000981:diagnostic imaging
C119803:2-fluoro-3-(2-azetidinylmethoxy)pyridine; D001384:Azetidines; D011725:Pyridines