title: Breath-hold MR measurements of fat fraction, T1 , and T2 * of water and fat in vertebral bone marrow.
abstract: To assess the feasibility of measuring the fat fraction, T1 and T2 * relaxation times of water and fat signals in vertebral bone marrow using breath-hold magnetic resonance imaging (MRI) gradient echo images of the spine.
  
  
  
  MRI experiments were performed at 1.5T on eight healthy volunteers (35.1 ± 15.7 years, five men and three women) using two sagittal four-echo 3D gradient echo volumetric interpolated breath-hold examination (VIBE Dixon) sequences acquired at two different flip angles (5° and 15°). The water/fat decomposition was performed in the vertebral bodies of L1 to L5 by fitting the signal to a function that depends on the echo time and the flip angle to calculate the fat fraction (FF) and T1 and T2 * relaxation times of water and fat signals. Repeatability was assessed by scanning one volunteer six times.
  
  
  
  The mean fat fraction over L1 to L5 was 33 ± 8%. The mean T1 and T2 * of water and fat signals were respectively T1w = 701 ± 151 msec, T2 *w = 13.7 ± 2.9 msec, T1f = 334 ± 113 msec, and T2 *f = 11.4 ± 2.7 msec. When considering each vertebra separately, the fat fraction increased from L1 to L5 and the T1w decreased from L1 to L5. The mean coefficients of variation obtained from the repeatability study were 8% (FF), 11% (T1w ), 17% (T1f ), 8% (T2 *w ), and 27% (T2 *f ).
  
  
  
  The method introduced in the current study allows for the measurement of the fat fraction and water and fat relaxation times, with a total acquisition time of less than 40 seconds. J. Magn. Reson. Imaging 2016;44:549-555.
authors.affiliation: INSERM, UMR 1099, Rennes, France.|Université de Rennes 1, LTSI, Rennes, France.|Siemens Healthcare, Saint-Denis, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Le Ster
authors.affiliation: INSERM, UMR 1099, Rennes, France.|Université de Rennes 1, LTSI, Rennes, France.
authors.forename: Giulio
authors.initials: G
authors.lastname: Gambarota
authors.affiliation: INSERM, UMR 1099, Rennes, France.|Université de Rennes 1, LTSI, Rennes, France.
authors.forename: Jérémy
authors.initials: J
authors.lastname: Lasbleiz
authors.affiliation: Department of Imaging, Rennes University Hospital, Rennes, France.
authors.forename: Raphaël
authors.initials: R
authors.lastname: Guillin
authors.affiliation: Department of Imaging, Rennes University Hospital, Rennes, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Decaux
authors.affiliation: INSERM, UMR 1099, Rennes, France.|Université de Rennes 1, LTSI, Rennes, France.|CRLCC, Centre Eugène Marquis, Rennes, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Saint-Jalmes
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging* / Q000502:physiology; D050154:Adiposity / Q000502:physiology; D000328:Adult; D001834:Body Water / Q000000981:diagnostic imaging* / Q000502:physiology; D001853:Bone Marrow / Q000000981:diagnostic imaging* / Q000502:physiology; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000502:physiology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D015656:Respiratory Mechanics; D012680:Sensitivity and Specificity; D055815:Young Adult
keywords: VIBE Dixon; chemical shift imaging; magnetic resonance imaging; relaxation times; vertebral bone marrow; vertebral fat fraction