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Oikonen, V.

Publications and source records attributed to Oikonen, V..

2 recordsLinked to original sources

TURBO: Automated Total-body PET Image Processing and Kinetic Modeling Toolbox

Long axial field of view (LAFOV) PET imaging requires a high level of automation and standardization, as the large number of target tissues increases the manual workload significantly. We introduce an automated analysis pipeline (TurBO, Turku total-BOdy) for preprocessing and kinetic modelling of LAFOV [15O]H2O and [18F]FDG PET data, enabling efficient and reproducible analysis of tissue perfusion and metabolism at regional and voxel-levels. The approach employs automated processing including co-registration, motion correction, automated CT segmentation for region of interest (ROI) delineation, image-derived input determination, and region-specific kinetic modelling of PET data. MethodsWe validated the analysis pipeline using Biograph Vision Quadra (Siemens Healthineers) LAFOV PET/CT scans from 21 subjects scanned with [15O]H2O and 16 subjects scanned with [18F]FDG using six segmented CT-based ROIs (cortical brain gray matter, left iliopsoas muscle, right kidney cortex and medulla, pancreas, spleen and liver) representing different levels of blood flow and glucose metabolism. ResultsModel fits showed good quality with consistent parameter estimates at both regional and voxel-levels (R{superscript 2} > 0.83 for [15O]H2O, R{superscript 2} > 0.99 for [18F]FDG). Estimates from manual and automated input functions were in concordance (R{superscript 2} > 0.74 for [15O]H2O, and R{superscript 2} > 0.78 for [18F]FDG) with minimal bias (<4% for [15O]H2O and <10% for [18F]FDG). Manually and automatically (CT-based) extracted ROI level data showed strong agreement (R{superscript 2} > 0.82 for [15O]H2O and R{superscript 2} > 0.83 for [18F]FDG), while motion correction had little impact on parameter estimates (R{superscript 2} > 0.71 for [15O]H2O and R{superscript 2} > 0.78 for [18F]FDG) compared with uncorrected data. ConclusionOur automated analysis pipeline provides reliable and reproducible parameter estimates across different regions, with an approximate processing time of 1-1.5 h per subject. This pipeline completely automates LAFOV PET analysis, reducing manual effort and enabling reproducible studies of inter-organ blood flow and metabolism, including brain-body interactions.

neuroscience↗

Photoperiod modulates mu-opioid receptor availability in brown adipose tissue

Photoperiod drives metabolic activity of brown adipose tissue (BAT), and affects food intake and weight gain in mammals. Sympathetic innervation in BAT controls thermogenesis and facilitates physiological adaption to seasons, but the exact mechanism remains elusive. Previous studies show that the central opioid signaling tunes BAT heating and the brain muopioid receptor (MOR) levels have seasonal patterns. It is hence intriguing to know whether the peripheral MOR signaling shows seasonal variation. Here, we examined the effect of photoperiod on BAT MOR availability using [11C]carfentanil positron emission topography (PET). Adult rats (n = 9) were repeatedly imaged under changing photoperiods which simulates the local seasons. Long photoperiod downregulated MOR availability in BAT, while MOR availability in the muscles was unaffected. We confirmed the expression of MOR in BAT and muscle using immunofluorescence imaging. We conclude that photoperiod causally affects MOR availability in BAT, and sympathetic innervation of BAT may influence thermogenesis via the peripheral MOR system. Significance of the studyPhotoperiod impacts the metabolic activity of brown adipose tissue (BAT) with the exact mechanism still unclear. The current study shows that photoperiod causally affects the mu-opioid receptor (MOR) levels in BAT, with longer photoperiod leading to lower MOR availability. This possibly indicates down-regulated innervation during bright seasons. Immunofluorescence staining data reveal expression of MOR in both brain and peripheral tissues, drawing attention to the under-investigated peripheral MOR system. Also, the study highlights the feasibility of [11C]carfentanil PET in studying the peripheral MOR signaling.

molecular biology↗