Twelve humans had two injections of [11C](R)-rolipram. An image-derived input function was obtained from the carotid arteries and four blood samples. The samples were used for partial volume correction and for estimating the parent concentration using HPLC analysis.
An unconstrained two-compartment model and Logan analysis measured distribution volume VT, with good identifiability but with moderately high retest variability (15 % ). Similar results were obtained using the image input (ratio image/arterial VT = 1.00 ± 0.06).
Binding of [11C](R)-rolipram to PDE4 can be quantified in human brain using kinetic modeling and an arterial input function. Image input function from carotid arteries provides an equally accurate and reproducible method to quantify PDE4.