title: Segmental quantitative MR imaging analysis of diurnal variation of water content in the lumbar intervertebral discs.
abstract: OBJECTIVE
  To investigate the changes in water content in the lumbar intervertebral discs by quantitative T2 MR imaging in the morning after bed rest and evening after a diurnal load.
  
  
  METHODS
  Twenty healthy volunteers were separately examined in the morning after bed rest and in the evening after finishing daily work. T2-mapping images were obtained and analyzed. An equally-sized rectangular region of interest (ROI) was manually placed in both, the anterior and the posterior annulus fibrosus (AF), in the outermost 20% of the disc. Three ROIs were placed in the space defined as the nucleus pulposus (NP). Repeated-measures analysis of variance and paired 2-tailed t tests were used for statistical analysis, with p < 0.05 as significantly different.
  
  
  RESULTS
  T2 values significantly decreased from morning to evening, in the NP (anterior NP = -13.9 ms; central NP = -17.0 ms; posterior NP = -13.3 ms; all p < 0.001). Meanwhile T2 values significantly increased in the anterior AF (+2.9 ms; p = 0.025) and the posterior AF (+5.9 ms; p < 0.001). T2 values in the posterior AF showed the largest degree of variation among the 5 ROIs, but there was no statistical significance (p = 0.414). Discs with initially low T2 values in the center NP showed a smaller degree of variation in the anterior NP and in the central NP, than in discs with initially high T2 values in the center NP (10.0% vs. 16.1%, p = 0.037; 6.4% vs. 16.1%, p = 0.006, respectively).
  
  
  CONCLUSIONS
  Segmental quantitative T2 MRI provides valuable insights into physiological aspects of normal discs.
authors.affiliation: Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Zhu
authors.affiliation: Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Ai
authors.affiliation: Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Li
authors.affiliation: Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Li
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007403:Intervertebral Disc / Q000000981:diagnostic imaging*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D008297:Male; D011859:Radiography; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water
keywords: Intervertebral disc; Quantitative MRI; Spine; T2 mapping