title: Optimized protocol for high resolution functional magnetic resonance imaging at 3T using single-shot echo planar imaging.
abstract: BACKGROUND
  To translate highly accelerated EPI-fMRI protocols as commonly used at ultra-high field strengths to clinical 3T settings.
  
  
  METHODS
  EPI protocols with increasing matrix sizes and parallel imaging (PI) factors were tested in two separate fMRI studies, a simple motor-task and a complex motivation-task experiment with focus on the sensorimotor cortex (SMC) and the nucleus accumbens (NAcc), respectively.
  
  
  RESULTS
  By increasing the matrix size and the PI-factor simultaneously, BOLD-sensitivity in terms of maximal t-values and numbers of activated clusters was uncompromised in single individuals in both fMRI experiments. In the SMC, the multi-subject analysis revealed an increase of 66% of the maximal t-value whereby the number of activated clusters was increased by a factor of 3.3 when the matrix size (PI-factor) was increased from 96×96 (R=2) to 192×192 (R=4). In the NAcc, the number of activated clusters increased from 5 to 7 whereby the maximal t-value remained unaffected when the matrix size (PI-factor) was increased from 96×96 (R=2) to 160×160 (R=3).
  
  
  CONCLUSIONS
  Using the proposed high-resolution EPI protocol, spatial blurring was clearly reduced. Further, BOLD sensitivity was clearly improved in multi-subject analyses and remained unaffected in single individuals compared to using the standard protocols.
  
  
  CONCLUSIONS
  Conventionally used matrix sizes (PI-factors) might be non-optimal for some applications sacrificing BOLD spatial specificity. We recommend using the proposed high-resolution protocols applicable in detecting robust BOLD activation in fMRI.
authors.affiliation: Department of Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Germany. Electronic address: sebastian.domsch@medma.uni-heidelberg.de.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Domsch
authors.affiliation: Department of Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Germany.
authors.forename: Jascha
authors.initials: J
authors.lastname: Zapp
authors.affiliation: Department of Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Germany.
authors.forename: Lothar R
authors.initials: LR
authors.lastname: Schad
authors.affiliation: Department of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Germany.
authors.forename: Frauke
authors.initials: F
authors.lastname: Nees
authors.affiliation: Department of Addictive Behavior and Addiction Medicine, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Hill
authors.affiliation: Department of Addictive Behavior and Addiction Medicine, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Germany.
authors.forename: Derik
authors.initials: D
authors.lastname: Hermann
authors.affiliation: Department of Addictive Behavior and Addiction Medicine, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Germany.
authors.forename: Karl
authors.initials: K
authors.lastname: Mann
authors.affiliation: Department of Addictive Behavior and Addiction Medicine, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Vollstädt-Klein
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology* / Q000098:blood supply* / Q000502:physiology; D001931:Brain Mapping; D017352:Echo-Planar Imaging; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D009042:Motivation; D011597:Psychomotor Performance; D055815:Young Adult
keywords: Motivation; Nucleus accumbens; Parallel imaging; Somatosensori motor cortex; Spatial specificity; fMRI