title: Intramuscular adipose tissue determined by T1-weighted MRI at 3T primarily reflects extramyocellular lipids.
abstract: OBJECTIVE
  The purpose of this study was to assess relationships between intramuscular adipose tissue (IntraMAT) content determined by MRI and intramyocellular lipids (IMCL) and extramyocellular lipids (EMCL) determined by (1)H magnetic resonance spectroscopy ((1)H MRS) or echo intensity determined by B-mode ultrasonography of human skeletal muscles.
  
  
  METHODS
  Thirty young and elderly men and women were included. T1-weighted MRI was taken from the right mid-thigh to measure IntraMAT content of the vastus lateralis (VL) and biceps femoris (BF) using a histogram shape-based thresholding technique. IMCL and EMCL were measured from the VL and BF at the right mid-thigh using (1)H MRS. Ultrasonographic images were taken from the VL and BF of the right mid-thigh to measure echo intensity based on gray-scale level for quantitative analysis.
  
  
  RESULTS
  There was a significant correlation between IntraMAT content by MRI and EMCL of the VL and BF (VL, r=0.506, P<0.01; BF, r=0.591, P<0.001) and between echo intensity and EMCL of the VL and BF (VL, r=0.485, P<0.05; BF, r=0.648, P<0.01). IntraMAT content was also significantly correlated with echo intensity of the VL and BF (VL, r=0.404, P<0.05; BF, r=0.493, P<0.01).
  
  
  CONCLUSIONS
  Our study suggests that IntraMAT content determined by T1-weighted MRI at 3T primarily reflects extramyocellular lipids, not intramyocellular lipids, in human skeletal muscles.
authors.affiliation: Research Center of Health, Physical Fitness & Sports, 1 Furo, Chikusa, Nagoya, Aichi, 4648601, Japan; Graduate School of Education & Human Development, Nagoya University, 1 Furo, Chikusa, Nagoya, Aichi, 4648601, Japan. Electronic address: akima@nagoya-u.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Akima
authors.affiliation: Graduate School of Medicine, Nagoya University, 65 Tsurumai, Showa, Nagoya, Aichi 4668550, Japan.
authors.forename: Maya
authors.initials: M
authors.lastname: Hioki
authors.affiliation: Graduate School of Medicine, Nagoya University, 65 Tsurumai, Showa, Nagoya, Aichi 4668550, Japan.
authors.forename: Akito
authors.initials: A
authors.lastname: Yoshiko
authors.affiliation: Research Center of Health, Physical Fitness & Sports, 1 Furo, Chikusa, Nagoya, Aichi, 4648601, Japan; Graduate School of Medicine, Nagoya University, 65 Tsurumai, Showa, Nagoya, Aichi 4668550, Japan.
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Koike
authors.affiliation: Graduate School of Medicine, Nagoya University, 65 Tsurumai, Showa, Nagoya, Aichi 4668550, Japan.
authors.forename: Hisataka
authors.initials: H
authors.lastname: Sakakibara
authors.affiliation: Japan Institute of Sports Sciences, 3-15-1 Nishigaoka, Kita, Tokyo 1150056, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Research Center of Health, Physical Fitness & Sports, 1 Furo, Chikusa, Nagoya, Aichi, 4648601, Japan; Graduate School of Medicine, Nagoya University, 65 Tsurumai, Showa, Nagoya, Aichi 4668550, Japan.
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Oshida
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging*; D050154:Adiposity; D000368:Aged; D005260:Female; D000070633:Hamstring Muscles / Q000000981:diagnostic imaging*; D006801:Humans; D008055:Lipids / Q000032:analysis*; D008279:Magnetic Resonance Imaging; D008297:Male; D052097:Quadriceps Muscle / Q000000981:diagnostic imaging*; D013848:Thigh; D014463:Ultrasonography; D055815:Young Adult
chemical_list: D008055:Lipids
keywords: Extramyocellular lipids; Image analysis; Intramuscular adipose tissue; Intramyocellular lipids; Spin-echo sequence; Ultrasonography