title: Improving perfusion quantification in arterial spin labeling for delayed arrival times by using optimized acquisition schemes.
abstract: OBJECTIVE
  The improvement in Arterial Spin Labeling (ASL) perfusion quantification, especially for delayed bolus arrival times (BAT), with an acquisition redistribution scheme mitigating the T1 decay of the label in multi-TI ASL measurements is investigated. A multi inflow time (TI) 3D-GRASE sequence is presented which adapts the distribution of acquisitions accordingly, by keeping the scan time constant.
  
  
  METHODS
  The MR sequence increases the number of averages at long TIs and decreases their number at short TIs and thus compensating the T1 decay of the label. The improvement of perfusion quantification is evaluated in simulations as well as in-vivo in healthy volunteers and patients with prolonged BATs due to age or steno-occlusive disease.
  
  
  RESULTS
  The improvement in perfusion quantification depends on BAT. At healthy BATs the differences are small, but become larger for longer BATs typically found in certain diseases. The relative error of perfusion is improved up to 30% at BATs>1500ms in comparison to the standard acquisition scheme.
  
  
  CONCLUSIONS
  This adapted acquisition scheme improves the perfusion measurement in comparison to standard multi-TI ASL implementations. It provides relevant benefit in clinical conditions that cause prolonged BATs and is therefore of high clinical relevance for neuroimaging of steno-occlusive diseases.
authors.affiliation: Fraunhofer MEVIS-Institute for Medical Image Computing, Bremen, Germany; Faculty of Physics and Electronics, University of Bremen, Germany. Electronic address: Johanna.Kramme@mevis.fraunhofer.de.
authors.forename: Johanna
authors.initials: J
authors.lastname: Kramme
authors.affiliation: mediri GmbH, Heidelberg, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Gregori
authors.affiliation: Fraunhofer MEVIS-Institute for Medical Image Computing, Bremen, Germany; ZEMODI (Zentrum für moderne Diagnostik), Bremen, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Diehl
authors.affiliation: Center for Stroke Research Berlin (CSB) Charité-Universitätsmedizin Berlin, Germany; Department of Neurology, Charité-Universitätsmedizin Berlin, Germany.
authors.forename: Vince I
authors.initials: VI
authors.lastname: Madai
authors.affiliation: Fraunhofer MEVIS-Institute for Medical Image Computing, Bremen, Germany; Center for Stroke Research Berlin (CSB) Charité-Universitätsmedizin Berlin, Germany; Department of Neurology, Charité-Universitätsmedizin Berlin, Germany.
authors.forename: Federico C
authors.initials: FC
authors.lastname: von Samson-Himmelstjerna
authors.affiliation: ZEMODI (Zentrum für moderne Diagnostik), Bremen, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Lentschig
authors.affiliation: Center for Stroke Research Berlin (CSB) Charité-Universitätsmedizin Berlin, Germany; Department of Neurology, Charité-Universitätsmedizin Berlin, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Sobesky
authors.affiliation: Fraunhofer MEVIS-Institute for Medical Image Computing, Bremen, Germany; Faculty of Physics and Electronics, University of Bremen, Germany; mediri GmbH, Heidelberg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Günther
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001783:Blood Flow Velocity; D016893:Carotid Stenosis / Q000175:diagnosis* / Q000503:physiopathology*; D003198:Computer Simulation; D003287:Contrast Media / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels
chemical_list: D003287:Contrast Media; D013113:Spin Labels
keywords: ASL; Arterial Spin Labeling; Bolus-Ankunftszeit; Magnetic Resonance Imaging; Magnetresonanz-Bildgebung; Perfusion; Signal zu Rauschen; bolus arrival time; optimierte Bildaufnahme; optimized acquisition; perfusion; signal to noise