title: High-resolution anatomy of the human brain stem using 7-T MRI: improved detection of inner structures and nerves?
abstract: BACKGROUND
  The purpose of this paper is to assess the value of 7 Tesla (7 T) MRI for the depiction of brain stem and cranial nerve (CN) anatomy.
  
  
  METHODS
  Six volunteers were examined at 7 T using high-resolution SWI, MPRAGE, MP2RAGE, 3D SPACE T2, T2, and PD images to establish scanning parameters targeted at optimizing spatial resolution. Direct comparisons between 3 and 7 T were performed in two additional subjects using the finalized sequences (3 T: T2, PD, MPRAGE, SWAN; 7 T: 3D T2, MPRAGE, SWI, MP2RAGE). Artifacts and the depiction of structures were evaluated by two neuroradiologists using a standardized score sheet.
  
  
  RESULTS
  Sequences could be established for high-resolution 7 T imaging even in caudal cranial areas. High in-plane resolution T2, PD, and SWI images provided depiction of inner brain stem structures such as pons fibers, raphe, reticular formation, nerve roots, and periaqueductal gray. MPRAGE and MP2RAGE provided clear depiction of the CNs. 3D T2 images improved depiction of inner brain structure in comparison to T2 images at 3 T. Although the 7-T SWI sequence provided improved contrast to some inner structures, extended areas were influenced by artifacts due to image disturbances from susceptibility differences.
  
  
  CONCLUSIONS
  Seven-tesla imaging of basal brain areas is feasible and might have significant impact on detection and diagnosis in patients with specific diseases, e.g., trigeminal pain related to affection of the nerve root. Some inner brain stem structures can be depicted at 3 T, but certain sequences at 7 T, in particular 3D SPACE T2, are superior in producing anatomical in vivo images of deep brain stem structures.
authors.affiliation: Department of Neuroradiology, Medical University Innsbruck, Anichstr. 35, A-6020, Innsbruck, Austria, elke.gizewski@i-med.ac.at.
authors.forename: Elke R
authors.initials: ER
authors.lastname: Gizewski
authors.forename: Stefan
authors.initials: S
authors.lastname: Maderwald
authors.forename: Jennifer
authors.initials: J
authors.lastname: Linn
authors.forename: Benjamin
authors.initials: B
authors.lastname: Dassinger
authors.forename: Katja
authors.initials: K
authors.lastname: Bochmann
authors.forename: Michael
authors.initials: M
authors.lastname: Forsting
authors.forename: Mark E
authors.initials: ME
authors.lastname: Ladd
mesh_terms: D000328:Adult; D000465:Algorithms; D001933:Brain Stem / Q000033:anatomy & histology*; D003391:Cranial Nerves / Q000033:anatomy & histology*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000648:ultrastructure*; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult