Correcting bias by accounting for radiotracer clearance in tissue: A validation study with [F]FE-PE2I PET in cross-sectional, test-retest and longitudinal cohorts.

Quantification of dopamine transporter (DAT) with [F]FE-PE2I PET is an important progression marker for Parkinson's disease (PD). This study aimed to validate a novel correction (c) for a less-biased estimate of by accounting for [F]FE-PE2I clearance-rate, in independent cross-sectional (38 PD, 38 controls), test-retest (9 PD) and longitudinal cohorts (21 PD). c was calculated as .

Pilot PET study of vaginally administered bioadhesive nanoparticles in cynomolgus monkeys: Kinetics and safety evaluation.

Long-lasting vaginal dosage forms could improve the therapeutic efficacy of vaginal microbicides, but achieving long-term delivery to the vaginal canal has been a significant challenge. To advance understanding of vaginal dosage retention and biodistribution, we describe a method of noninvasive imaging with Zr-labeled bioadhesive nanoparticles (BNPs) in non-human primates. We additionally examined the safety of repeated BNP application.

Clinical correlates of dopamine transporter availability in cross-sectional and longitudinal studies with [F]FE-PE2I PET: independent validation with new insights.

[F]FE-PE2I PET is a promising alternative to single positron emission computed tomography-based dopamine transporter (DAT) imaging in Parkinson's disease. While the excellent discriminative power of [F]FE-PE2I PET has been established, so far only one study has reported meaningful associations between motor severity scores and DAT availability. In this study, we use high-resolution (∼3 mm isotropic) PET to provide an independent validation for the clinical correlates of [F]FE-PE2I imaging in separate cross-sectional (28 participants with Parkinson's disease, Hoehn-Yahr: 2 and 14 healthy individuals) and longitudinal (initial results from 6 participants with Parkinson's disease with 2-year follow-up) cohorts.

Synaptic loss and its association with symptom severity in Parkinson's disease.

Parkinson's disease (PD) is the fastest growing neurodegenerative disease, but at present there is no cure, nor any disease-modifying treatments. Synaptic biomarkers from in vivo imaging have shown promise in imaging loss of synapses in PD and other neurodegenerative disorders. Here, we provide new clinical insights from a cross-sectional, high-resolution positron emission tomography (PET) study of 30 PD individuals and 30 age- and sex-matched healthy controls (HC) with the radiotracer [C]UCB-J, which binds to synaptic vesicle glycoprotein 2A (SV2A), and is therefore, a biomarker of synaptic density in the living brain.

Improving quantification by correcting for radiotracer clearance in tissue.

Standardized Uptake Value Ratio () is a widely reported semi-quantitative positron emission tomography (PET) outcome measure, partly because of its ease of measurement from short scan durations. However, in brain, is often a biased estimator of the gold-standard distribution volume ratio () due to non-equilibrium conditions, i.e.