title: Optimization of Inversion Time for Postmortem Fluid-attenuated Inversion Recovery (FLAIR) MR Imaging at 1.5T: Temperature-based Suppression of Cerebrospinal Fluid.
abstract: OBJECTIVE
  Signal intensity (SI) and image contrast on postmortem magnetic resonance (MR) imaging are different from those of imaging of living bodies. We sought to suppress the SI of cerebrospinal fluid (CSF) sufficiently for fluid-attenuated inversion recovery (FLAIR) sequence in postmortem MR (PMMR) imaging by optimizing inversion time (TI).
  
  
  METHODS
  We subject 28 deceased patients to PMMR imaging 3 to 113 hours after confirmation of death (mean, 27.4 hrs.). PMMR imaging was performed at 1.5 tesla, and T1 values of CSF were measured with maps of relaxation time. Rectal temperatures (RT) measured immediately after PMMR imaging ranged from 6 to 32°C (mean, 15.4°C). We analyzed the relationship between T1 and RT statistically using Pearson's correlation coefficient. We obtained FLAIR images from one cadaver using both a TI routinely used for living bodies and an optimized TI calculated from the RT.
  
  
  RESULTS
  T1 values of CSF ranged from 2159 to 4063 ms (mean 2962.4), and there was a significantly positive correlation between T1 and RT (r = 0.96, P < 0.0001). The regression expression for the relationship was T1 = 74.4 * RT + 1813 for a magnetic field strength of 1.5T. The SI of CSF was effectively suppressed with the optimized TI (0.693 * T1), namely, TI = 0.693 * (77.4 * RT + 1813).
  
  
  CONCLUSIONS
  Use of the TI calculated from the linear regression of the T1 and RT optimizes the FLAIR sequence of PMMR imaging.
authors.affiliation: Department of Radiological Science, Faculty of Health Sciences, Junshin Gakuen University.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Abe
authors.forename: Tomoya
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Seiji
authors.initials: S
authors.lastname: Shiotani
authors.forename: Hajime
authors.initials: H
authors.lastname: Saito
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kaga
authors.forename: Kazuya
authors.initials: K
authors.lastname: Tashiro
authors.forename: Satoka
authors.initials: S
authors.lastname: Someya
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Hayakawa
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Homma
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019412:Anatomy, Cross-Sectional / Q000379:methods; D001344:Autopsy; D001831:Body Temperature / Q000502:physiology*; D002102:Cadaver; D002555:Cerebrospinal Fluid; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D007223:Infant; D020547:Lateral Ventricles / Q000033:anatomy & histology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods; D013997:Time Factors; D055815:Young Adult