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Background: Kinetic modeling of 18F-florbetaben provides important quantification of brain amyloid deposition in research and clinical settings but its use is limited by the requirement of arterial blood data for quantitative PET. The total-body EXPLORER PET scanner supports the dynamic acquisition of a full human body simultaneously and permits noninvasive image-derived input functions (IDIFs) as an alternative to arterial blood sampling. This study quantified brain amyloid burden with kinetic modeling, leveraging dynamic 18F-florbetaben PET in aorta IDIFs and the brain in an elderly cohort. Methods: 18F-florbetaben dynamic PET imaging was performed on the EXPLORER system with tracer injection (300 MBq) in 3 individuals with Alzheimer's disease (AD), 3 with mild cognitive impairment, and 9 healthy controls. Image-derived input functions were extracted from the descending aorta with manual regions of interest based on the first 30 s after injection. Dynamic time-activity curves (TACs) for 110 min were fitted to the two-tissue compartment model (2TCM) using population-based metabolite corrected IDIFs to calculate total and specific distribution volumes (VT, Vs) in key brain regions with early amyloid accumulation. Non-displaceable binding potential ( was also calculated from the multi-reference tissue model (MRTM). Results: Amyloid-positive (AD) patients showed the highest VT and VS in anterior cingulate, posterior cingulate, and precuneus, consistent with analysis. and VT from kinetic models were correlated (r² = 0.46, P < 2 with a stronger positive correlation observed in amyloid-positive participants, indicating reliable model fits with the IDIFs. VT from 2TCM was highly correlated ( = 0.65, P < 2 ) with Logan graphical VT estimation. Conclusion: Non-invasive quantification of amyloid binding from total-body 18F-florbetaben PET data is feasible using aorta IDIFs with high agreement between kinetic distribution volume parameters compared to in amyloid-positive and amyloid-negative older individuals. [ABSTRACT FROM AUTHOR]

Purpose: Knowing the precise flow of cerebrospinal fluid (CSF) is important in the management of multiple neurological diseases. Technology for non-invasively quantifying CSF flow would allow for precise localization of injury and assist in evaluating the viability of certain devices placed in the central nervous system (CNS). Methods: We describe a near-infrared fluorescent dye for accurately monitoring CSF flow by positron emission tomography (PET) and fluorescence. IR-783, a commercially available near-infrared dye, was chemically modified and radiolabeled with fluorine-18 to give [18F]-IR783-AMBF3. [18F]-IR783-AMBF3 was intrathecally injected into the rat models with normal and aberrant CSF flow and evaluated by the fluorescence and PET/MRI or PET/CT imaging modes. Results: IR783-AMBF3 was clearly distributed in CSF-containing volumes by PET and fluorescence. We compared IR783-AMBF3 (fluorescent at 778/793 nm, ex/em) to a shorter-wavelength, fluorescein equivalent (fluorescent at 495/511 nm, ex/em). IR783-AMBF3 was superior for its ability to image through blood (hemorrhage) and for imaging CSF-flow, through-skin, in subdural-run lumboperitoneal shunts. IR783-AMBF3 was safe under the tested dosage both in vitro and in vivo. Conclusion: The superior imaging properties of IR783-AMBF3 could lead to enhanced accuracy in the treatment of patients and would assist surgeons in non-invasively diagnosing diseases of the CNS. [ABSTRACT FROM AUTHOR]