title: Estimation of arterial arrival time and cerebral blood flow from QUASAR arterial spin labeling using stable spline.
abstract: OBJECTIVE
  QUASAR arterial spin labeling (ASL) permits the application of deconvolution approaches for the absolute quantification of cerebral perfusion. Currently, oscillation index regularized singular value decomposition (oSVD) combined with edge-detection (ED) is the most commonly used method. Its major drawbacks are nonphysiological oscillations in the impulse response function and underestimation of perfusion. The aim of this work is to introduce a novel method to overcome these limitations.
  
  
  METHODS
  A system identification method, stable spline (SS), was extended to address ASL peculiarities such as the delay in arrival of the arterial blood in the tissue. The proposed framework was compared with oSVD + ED in both simulated and real data. SS was used to investigate the validity of using a voxel-wise tissue T1 value instead of using a single global value (of blood T1 ).
  
  
  RESULTS
  SS outperformed oSVD + ED in 79.9% of simulations. When applied to real data, SS exhibited a physiologically realistic range for perfusion and a higher mean value with respect to oSVD + ED (55.5 ± 9.5 SS, 34.9 ± 5.2 oSVD + ED mL/100 g/min).
  
  
  CONCLUSIONS
  SS can represent an alternative to oSVD + ED for the quantification of QUASAR ASL data. Analysis of the retrieved impulse response function revealed that using a voxel wise tissue T1 might be suboptimal.
authors.affiliation: Department of Information Engineering, University of Padova, Padova, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Castellaro
authors.affiliation: Department of Neuroimaging, Research institute IRCCS "E. Medea", Bosisio Parini, LC, Italy.
authors.forename: Denis
authors.initials: D
authors.lastname: Peruzzo
authors.affiliation: Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom.|Centre for Biomedical Engineering, Indian Institute of Technology, Delhi, India.
authors.forename: Amit
authors.initials: A
authors.lastname: Mehndiratta
authors.affiliation: Department of Information Engineering, University of Padova, Padova, Italy.
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Pillonetto
authors.affiliation: Departments of Radiology and Radiotherapy, University Medical Center, Utrecht, Netherlands.
authors.forename: Esben Thade
authors.initials: ET
authors.lastname: Petersen
authors.affiliation: University College London, Institute of Neurology, London, United Kingdom.
authors.forename: Xavier
authors.initials: X
authors.lastname: Golay
authors.affiliation: Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Chappell
authors.affiliation: Department of Information Engineering, University of Padova, Padova, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Bertoldo
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology*; D002536:Cerebral Arteries / Q000033:anatomy & histology / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels
chemical_list: D013113:Spin Labels
keywords: QUASAR; arterial spin labelling; cerebral blood flow (CBF); deconvolution; perfusion; stable spline