title: [Age-related changes of normal adult inferior rectus muscle:analysis with dynamic contrast-enhanced magnetic resonance imaging].
abstract: OBJECTIVE
  To explore the age-related changes of blood supply and extracellular space volume in normal adult inferior rectus muscle, evaluate the microcirculation in extraocular muscle and offer important information for the diagnosis and treatment of extraocular muscle disorders.
  
  
  METHODS
  A total of 250 patients undergoing nose-sinus dynamic contrast-enhanced magnetic resonance imaging were studied. Five groups were divided according to age (20 - 30 yr old, 30 - 40 yr old, 40 - 50 yr old, 50 - 60 yr old and over 60 yr old). The technique of 3DFSPGR (3-dimensional fast spoiled gradient-recalled) was used in dynamic contrast-enhanced imaging scanning 4 minutes and 59 seconds and acquiring 12 phases. Time-intensity curves of orbital layer, global layer of inferior rectus muscle and temporal muscle ipsilaterally were drawn on post-process work station. From the curves, the values of SIpre, SImax and SIphase12 were obtained and then SIpeak (peak signal intensity), Tpeak (time of peak enhancement) and WR (washout ratio) computed. The data were analyzed statistically.
  
  
  RESULTS
  SIpeak of orbital layer in all groups was as follows: 404.7 ± 12.7, 395.1 ± 15.9, 367.3 ± 5.1, 307.0 ± 12.4 and 265.3 ± 6.2 respectively. Tpeak: (85.2 ± 1.0) s, (93.2 ± 8.1) s, (106.8 ± 4.6), (122.8 ± 8.6) s and (133.0 ± 0.8) s respectively. WR: (9.25 ± 0.50)%, (8.25 ± 0.50)%, (7.50 ± 0.58)%, (4.75 ± 1.26)% and (3.50 ± 1.73)% respectively. SIpeak of global layer in all groups was as follows:261.9 ± 2.1, 256.6 ± 1.1, 243.8 ± 3.3, 225.4 ± 4.9 and 219.8 ± 5.3 respectively. Tpeak: (157.8 ± 1.7) s, (166.5 ± 4.5) s, (173.2 ± 7.2) s, (192.8 ± 9.1) s and (200.5 ± 2.4) s respectively. WR: (7.25 ± 0.50)%, (6.27 ± 0.00)%, (4.50 ± 0.58)%, (3.75 ± 0.50)% and (2.25 ± 1.50)% respectively. SIpeak, Tpeak and WR of temporal muscle in all groups showed no statistical significance (P > 0.05). Tpeak increased while SIpeak and WR decreased with age. Furthermore the changes of Tpeak of orbital layer were more sensitive.
  
  
  CONCLUSIONS
  Dynamic contrast-enhanced magnetic resonance imaging can non-invasively reflect the age-related changes of blood supply and extracellular space volume in normal adult inferior rectus muscle so as to offer important information for the diagnosis and treatment of extraocular muscle disorders.
authors.affiliation: Department of Medical Imaging Center, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Jiang
authors.forename: Zhen-chang
authors.initials: ZC
authors.lastname: Wang
authors.forename: Jun-fang
authors.initials: JF
authors.lastname: Xian
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Peng-fei
authors.initials: PF
authors.lastname: Zhao
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009801:Oculomotor Muscles / Q000033:anatomy & histology* / Q000502:physiology*; D055815:Young Adult