title: Sodium ((23)Na) ultra-short echo time imaging in the human brain using a 3D-Cones trajectory.
abstract: OBJECTIVE
  Sodium magnetic resonance imaging ((23)Na-MRI) of the brain has shown changes in (23)Na signal as a hallmark of various neurological diseases such as stroke, Alzheimer's disease, Multiple Sclerosis and Huntington's disease. To improve scan times and image quality, we have implemented the 3D-Cones (CN) sequence for in vivo (23)Na brain MRI.
  
  
  METHODS
  Using signal-to-noise (SNR) as a measurement of sequence performance, CN is compared against more established 3D-radial k-space sampling schemes featuring cylindrical stack-of-stars (SOS) and 3D-spokes kooshball (KB) trajectories, on five healthy volunteers in a clinical setting. Resolution was evaluated by simulating the point-spread-functions (PSFs) and experimental measures on a phantom.
  
  
  RESULTS
  All sequences were shown to have a similar SNR arbitrary units (AU) of 6-6.5 in brain white matter, 7-9 in gray matter and 17-18 AU in cerebrospinal fluid. SNR between white and gray matter were significantly different for KB and CN (p = 0.046 and <0.001 respectively), but not for SOS (p = 0.1). Group mean standard deviations were significantly smaller for CN (p = 0.016). Theoretical full-width at half-maximum linewidth of the PSF for CN is broadened by only 0.1, compared to 0.3 and 0.8 pixels for SOS and KB respectively. Actual image resolution is estimated as 8, 9 and 6.3 mm for SOS, KB and CN respectively.
  
  
  CONCLUSIONS
  The CN sequence provides stronger tissue contrast than both SOS and KB, with more reproducible SNR measurements compared to KB. For CN, a higher true resolution in the same amount of time with no significant trade-off in SNR is achieved. CN is therefore more suitable for (23)Na-MRI in the brain.
authors.affiliation: NMR Research Unit, Department of Neuroinflammation, Queen Square MS Centre, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK, frank.riemer.10@ucl.ac.uk.
authors.forename: Frank
authors.initials: F
authors.lastname: Riemer
authors.forename: Bhavana S
authors.initials: BS
authors.lastname: Solanky
authors.forename: Christian
authors.initials: C
authors.lastname: Stehning
authors.forename: Matthew
authors.initials: M
authors.lastname: Clemence
authors.forename: Claudia A M
authors.initials: CA
authors.lastname: Wheeler-Kingshott
authors.forename: Xavier
authors.initials: X
authors.lastname: Golay
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio; D012964:Sodium / Q000737:chemistry*
chemical_list: D012964:Sodium
references.citation: Magn Reson Med. 2006 May;55(5):1075-82
references.pmid: 16538604
references.citation: Magn Reson Med. 2013 Feb;69(2):495-502
references.pmid: 22473708
references.citation: Osteoarthritis Cartilage. 2000 Jul;8(4):288-93
references.pmid: 10903883
references.citation: Med Phys. 1985 Mar-Apr;12(2):232-3
references.pmid: 4000083
references.citation: AJNR Am J Neuroradiol. 2009 May;30(5):978-84
references.pmid: 19213826
references.citation: Magn Reson Med. 2006 Mar;55(3):575-82
references.pmid: 16450366
references.citation: Magn Reson Med. 1994 Dec;32(6):778-84
references.pmid: 7869901
references.citation: Magn Reson Med. 2012 Mar;67(3):701-10
references.pmid: 21688320
references.citation: Radiology. 2012 Sep;264(3):859-67
references.pmid: 22807483
references.citation: Neuroimage. 2012 Oct 15;63(1):517-24
references.pmid: 22796981
references.citation: Brain. 2010 Mar;133(Pt 3):847-57
references.pmid: 20110245
references.citation: Magn Reson Med. 2000 Jun;43(6):867-75
references.pmid: 10861882
references.citation: NMR Biomed. 2012 Apr;25(4):530-7
references.pmid: 21853493
references.citation: Magn Reson Med. 1992 Dec;28(2):275-89
references.pmid: 1461126
references.citation: Magn Reson Med. 2009 Dec;62(6):1565-73
references.pmid: 19859915
references.citation: Magn Reson Med. 2004 Jul;52(1):197-203
references.pmid: 15236387
references.citation: Magn Reson Med. 2012 Jul;68(1):227-33
references.pmid: 22144258
references.citation: Magn Reson Med. 1999 Jan;41(1):179-86
references.pmid: 10025627
references.citation: Magn Reson Med. 1997 May;37(5):706-15
references.pmid: 9126944
references.citation: Magn Reson Med. 1997 Apr;37(4):569-75
references.pmid: 9094079
references.citation: Stroke. 2006 Mar;37(3):883-8
references.pmid: 16424376
references.citation: J Magn Reson Imaging. 1992 Jan-Feb;2(1):47-52
references.pmid: 1623280
references.citation: IEEE Trans Med Imaging. 1985;4(4):200-7
references.pmid: 18243972