title: Towards a reproducible protocol for repetitive and semi-quantitative rat brain imaging with (18) F-FDG: exemplified in a memantine pharmacological challenge.
abstract: The standard uptake value (SUV), commonly used to quantify (18)F-FluoroDeoxyGlucose (FDG) uptake in small animal brain PET imaging, is affected by many factors. In this study the influence of fasting times, inter-scan duration and repetitive scanning on the variability of different SUV measures is investigated. Additionally it is demonstrated that these variables could adversely influence the outcome of a pharmacological challenge when not accounted for. Naive Sprague-Dawley rats (n=20) were randomly divided into five different fasting groups (no fasting up to 24h of fasting). SUV brain uptake values were reproducible in naive animals when a fasting period of at least 12h is used and for shorter fasting periods SUV values need to be corrected for the glucose level. Additionally, a separate animal group (n=6) was sufficiently fasted for 16h and in a longitudinal setting being scanned six times in three weeks. Especially with short inter-scan durations, increasing glucose levels were found over time which was attributed to increased stress due to repeated food deprivation, altered food intake or scan manipulations. As a result, even with controlled and sufficient fasting, blood glucose levels should be taken into account for data quantification. Strikingly, even the brain activation effects of an NMDA-antagonist challenge with memantine could not be detected in experiments with a short inter-scan duration if glucose levels were not taken into account. Correcting for glucose levels decreases the inter- and intra-animal variability for rat brain imaging. SUV corrected for glucose levels yields the lowest inter-animal variation. However, if the body weight changes significantly, as in a long experiment, quantification based on the glucose corrected percentage injected dose (and not SUV) is recommendable as this yields the lowest intra-animal variation.
authors.affiliation: Molecular Imaging Center Antwerp, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium. Electronic address: Steven.Deleye@uantwerpen.be.
authors.forename: Steven
authors.initials: S
authors.lastname: Deleye
authors.affiliation: Molecular Imaging Center Antwerp, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium. Electronic address: Jeroen.Verhaeghe@uantwerpen.be.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Verhaeghe
authors.affiliation: Molecular Imaging Center Antwerp, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium; Nuclear Medicine Department, University Hospital Antwerp, Wilrijkstraat 10, 2650 Antwerp, Belgium. Electronic address: Leonie.wyffels@uza.be.
authors.forename: Leonie
authors.initials: L
authors.lastname: wyffels
authors.affiliation: Translational Neurosciences, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium. Electronic address: Stefanie.Dedeurwaerdere@hotmail.com.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Dedeurwaerdere
authors.affiliation: Molecular Imaging Center Antwerp, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium; Nuclear Medicine Department, University Hospital Antwerp, Wilrijkstraat 10, 2650 Antwerp, Belgium. Electronic address: Sigrid.Stroobants@uza.be.
authors.forename: Sigrid
authors.initials: S
authors.lastname: Stroobants
authors.affiliation: Molecular Imaging Center Antwerp, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium. Electronic address: Steven.Staelens@uantwerpen.be.
authors.forename: Steven
authors.initials: S
authors.lastname: Staelens
mesh_terms: D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging* / Q000187:drug effects / Q000378:metabolism*; D003198:Computer Simulation; D005215:Fasting / Q000502:physiology*; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D007089:Image Enhancement / Q000379:methods; D008297:Male; D008559:Memantine / Q000494:pharmacology*; D008657:Metabolic Clearance Rate / Q000187:drug effects; D008954:Models, Biological; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D008559:Memantine
keywords: (18) F-FDG; Brain; Glucose; PET; Rat; SUV