title: Q-ball imaging models: comparison between high and low angular resolution diffusion-weighted MRI protocols for investigation of brain white matter integrity.
abstract: BACKGROUND
  Q-ball imaging (QBI) is one of the typical data models for quantifying white matter (WM) anisotropy in diffusion-weighted MRI (DwMRI) studies. Brain and spinal investigation by high angular resolution DwMRI (high angular resolution imaging (HARDI)) protocols exhibits higher angular resolution in diffusion imaging compared to low angular resolution models, although with longer acquisition times. We aimed to assess the difference between QBI-derived anisotropy values from high and low angular resolution DwMRI protocols and their potential advantages or shortcomings in neuroradiology.
  
  
  METHODS
  Brain DwMRI data sets were acquired in seven healthy volunteers using both HARDI (b = 3000 s/mm(2), 54 gradient directions) and low angular resolution (b = 1000 s/mm(2), 32 gradient directions) acquisition schemes. For both sequences, tract of interest tractography and generalized fractional anisotropy (GFA) measures were extracted by using QBI model and were compared between the two data sets.
  
  
  RESULTS
  QBI tractography and voxel-wise analyses showed that some WM tracts, such as corpus callosum, inferior longitudinal, and uncinate fasciculi, were reconstructed as one-dominant-direction fiber bundles with both acquisition schemes. In these WM tracts, mean percent different difference in GFA between the two data sets was less than 5%. Contrariwise, multidirectional fiber bundles, such as corticospinal tract and superior longitudinal fasciculus, were more accurately depicted by HARDI acquisition scheme.
  
  
  CONCLUSIONS
  Our results suggest that the design of optimal DwMRI acquisition protocols for clinical investigation of WM anisotropy by QBI models should consider the specific brain target regions to be explored, inducing researchers to a trade-off choice between angular resolution and acquisition time.
authors.affiliation: MRI Research Center SUN-FISM-Neurological Institute for Diagnosis and Care "Hermitage Capodimonte", Naples, Italy.|Department of Medical, Surgical, Neurological, Metabolic and Aging Sciences, Second University of Naples, Naples, Italy.
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Caiazzo
authors.affiliation: MRI Research Center SUN-FISM-Neurological Institute for Diagnosis and Care "Hermitage Capodimonte", Naples, Italy.|Department of Medical, Surgical, Neurological, Metabolic and Aging Sciences, Second University of Naples, Naples, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Trojsi
authors.affiliation: MRI Research Center SUN-FISM-Neurological Institute for Diagnosis and Care "Hermitage Capodimonte", Naples, Italy.|Department of Medical, Surgical, Neurological, Metabolic and Aging Sciences, Second University of Naples, Naples, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Cirillo
authors.affiliation: MRI Research Center SUN-FISM-Neurological Institute for Diagnosis and Care "Hermitage Capodimonte", Naples, Italy.|Department of Medical, Surgical, Neurological, Metabolic and Aging Sciences, Second University of Naples, Naples, Italy.
authors.forename: Gioacchino
authors.initials: G
authors.lastname: Tedeschi
authors.affiliation: Department of Medicine and Surgery, University of Salerno, Via Allende, 84081, Baronissi (Salerno), Italy. faesposito@unisa.it.|Department of Cognitive Neuroscience, Maastricht University, Maastricht, The Netherlands. faesposito@unisa.it.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Esposito
mesh_terms: D000328:Adult; D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D003198:Computer Simulation; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D015233:Models, Statistical; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D066127:White Matter / Q000033:anatomy & histology / Q000000981:diagnostic imaging*
keywords: DTI; Fiber tracts; Fractional anisotropy; HARDI; White matter