Image-derived input function for human brain using high resolution PET imaging with [C](R)-rolipram and [C]PBR28.

Background: The aim of this study was to test seven previously published image-input methods in state-of-the-art high resolution PET brain images. Images were obtained with a High Resolution Research Tomograph plus a resolution-recovery reconstruction algorithm using two different radioligands with different radiometabolite fractions. Three of the methods required arterial blood samples to scale the image-input, and four were blood-free methods.

Kinetic analysis in human brain of [11C](R)-rolipram, a positron emission tomographic radioligand to image phosphodiesterase 4: a retest study and use of an image-derived input function.

Unlabelled: [(11)C](R)-rolipram provides a measure of the density of phosphodiesterase 4 (PDE4) in brain, an enzyme that metabolizes cAMP. The aims of this study were to perform kinetic modeling of [(11)C](R)-rolipram in healthy humans using an arterial input function and to replace this arterial input in humans with an image-derived input function.

Methods: Twelve humans had two injections of [(11)C](R)-rolipram.

Determination of carbon isotope ratios in amino acids, proteins, and oligosaccharides by inductively coupled plasma-mass spectrometry.

Carbon isotope ratios ((12)C/(13)C) are measured for aqueous solutions of tryptophan, myoglobin, and beta-cyclodextrin using C(+) ions from an inductively coupled plasma (ICP) and a prototype twin quadrupole mass spectrometer (MS). (13)C/(12)C ratios can be determined with a relative standard deviation (RSD) of approximately 1%. This precision is close to the limiting value predicted by counting statistics (1.