title: Variability of physiological brain perfusion in healthy subjects - A systematic review of modifiers. Considerations for multi-center ASL studies.
abstract: Quantitative measurements of brain perfusion are influenced by perfusion-modifiers. Standardization of measurement conditions and correction for important modifiers is essential to improve accuracy and to facilitate the interpretation of perfusion-derived parameters. An extensive literature search was carried out for factors influencing quantitative measurements of perfusion in the human brain unrelated to medication use. A total of 58 perfusion modifiers were categorized into four groups. Several factors (e.g., caffeine, aging, and blood gases) were found to induce a considerable effect on brain perfusion that was consistent across different studies; for other factors, the modifying effect was found to be debatable, due to contradictory results or lack of evidence. Using the results of this review, we propose a standard operating procedure, based on practices already implemented in several research centers. Also, a theory of 'deep MRI physiotyping' is inferred from the combined knowledge of factors influencing brain perfusion as a strategy to reduce variance by taking both personal information and the presence or absence of perfusion modifiers into account. We hypothesize that this will allow to personalize the concept of normality, as well as to reach more rigorous and earlier diagnoses of brain disorders.
authors.affiliation: 1 Department of Radiology and nuclear medicine, Ghent University, Ghent, Belgium.
authors.forename: Patricia
authors.initials: P
authors.lastname: Clement
authors.affiliation: 2 Cognitive Neurology Research Unit, Sunnybrook Healthy Sciences Centre, Toronto, Canada.|3 Academic Medical Center, Amsterdam, the Netherlands.
authors.forename: Henk-Jan
authors.initials: HJ
authors.lastname: Mutsaerts
authors.affiliation: 3 Academic Medical Center, Amsterdam, the Netherlands.
authors.forename: Lena
authors.initials: L
authors.lastname: Václavů
authors.affiliation: 4 Leiden University Medical Center, Leiden, the Netherlands.
authors.forename: Eidrees
authors.initials: E
authors.lastname: Ghariq
authors.affiliation: 5 University Hospital Verona, Verona, Italy.
authors.forename: Francesca B
authors.initials: FB
authors.lastname: Pizzini
authors.affiliation: 6 Erasmus MC, Rotterdam, the Netherlands.
authors.forename: Marion
authors.initials: M
authors.lastname: Smits
authors.affiliation: 1 Department of Radiology and nuclear medicine, Ghent University, Ghent, Belgium.
authors.forename: Marjan
authors.initials: M
authors.lastname: Acou
authors.affiliation: 7 Magnetic Resonance Imaging Laboratory Center for Mind/Brain Sciences, University of Trento, Mattarello, Italy.
authors.forename: Jorge
authors.initials: J
authors.lastname: Jovicich
authors.affiliation: 8 Kuopio University Hospital, Kuopio, Finland.
authors.forename: Ritva
authors.initials: R
authors.lastname: Vanninen
authors.affiliation: 8 Kuopio University Hospital, Kuopio, Finland.
authors.forename: Mervi
authors.initials: M
authors.lastname: Kononen
authors.affiliation: 9 University Hospital Bern, Bern, Switzerland.
authors.forename: Roland
authors.initials: R
authors.lastname: Wiest
authors.affiliation: 10 Department of Diagnostics, Glostrup Hospital, University of Copenhagen, Denmark.
authors.forename: Egill
authors.initials: E
authors.lastname: Rostrup
authors.affiliation: 11 Department of Medical Imaging, University of Porto, Porto, Portugal.
authors.forename: António J
authors.initials: AJ
authors.lastname: Bastos-Leite
authors.affiliation: 12 Uppsala University, Uppsala, Sweden.
authors.forename: Elna-Marie
authors.initials: EM
authors.lastname: Larsson
authors.affiliation: 1 Department of Radiology and nuclear medicine, Ghent University, Ghent, Belgium.
authors.forename: Eric
authors.initials: E
authors.lastname: Achten
mesh_terms: D001921:Brain / Q000098:blood supply*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000592:standards; D015337:Multicenter Studies as Topic; D055420:Perfusion Imaging / Q000379:methods* / Q000592:standards*
keywords: Arterial spin labeling; cerebral perfusion; deep MRI physiotyping; physiology; variability