title: Intracranial time-of-flight MR angiography at 7T with comparison to 3T.
abstract: OBJECTIVE
  To establish the feasibility of intracranial time-of-flight (TOF) MR angiography (MRA) at 7T using phased array coils and to compare its performance to 3T.
  
  
  METHODS
  In an initial study, five normal volunteers were scanned at 7T and 3T using eight-channel coils and standard acquisition parameters from a clinical TOF protocol. In a second study three additional studies were performed at 7T and 3T using empirically optimized 7T parameters. Contrast-to-noise (CNR) values were measured for major vessel segments.
  
  
  RESULTS
  All measurements documented CNR increases at 7T, with a mean increase of 83% in the initial study and 88% in the second study. The CNR values achieved using the latter protocol were similar to the values obtained in the initial study, despite the 42% reduction expected due to the higher spatial resolution. CNR in the smaller peripheral vessels was increased dramatically, resulting in excellent visualization at high resolution.
  
  
  CONCLUSIONS
  TOF MRA at 7T demonstrated improved visualization of the intracranial vasculature, particularly the smaller peripheral vessels, and may benefit studies of small aneurysms, atherosclerosis, vasospasm, and vasculitis.
authors: Department of Radiology, UCSF, San Francisco, California, USA.
authors: Cornelius
authors: C
authors: von Morze
authors: Duan
authors: D
authors: Xu
authors: Derk D
authors: DD
authors: Purcell
authors: Christopher P
authors: CP
authors: Hess
authors: Pratik
authors: P
authors: Mukherjee
authors: David
authors: D
authors: Saloner
authors: Douglas A C
authors: DA
authors: Kelley
authors: Daniel B
authors: DB
authors: Vigneron
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology* / Q000473:pathology; D003287:Contrast Media; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D002532:Intracranial Aneurysm / Q000175:diagnosis / Q000473:pathology; D018810:Magnetic Resonance Angiography / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D013997:Time Factors
chemical_list: D003287:Contrast Media