title: Effect of ovariectomy on contrast agent diffusion into lumbar intervertebral disc: a dynamic contrast-enhanced MRI study in female rats.
abstract: OBJECTIVE
  The purpose was to study the effect of estrogen deficiency on contrast agent diffusion into intervertebral disc in a rat model.
  
  
  METHODS
  Seven-month-old female Sprague-Dawley rats were used. Fourteen rats had ovariectomy, and nine rats had sham surgery. Magnetic resonance imaging (MRI) of sagittal midsection of lumbar spine was performed with a 1.5-T magnet. Dynamic MRI was performed after a bolus injection of Gd-DOTA (0.3 mmol/kg) through tail vein. Eight hundred images were acquired at 0.6 s per acquisition. Regions of interests were drawn over three discs per rat. Maximum enhancement (E(max)) and enhancement slope (E(slope)) were evaluated. MRI was carried out at baseline and 8 weeks postsurgery.
  
  
  RESULTS
  All disc enhancements demonstrated an initial fast wash-in phase followed by a second slower wash-in phase. For initial wash-in phase, E(1)(max) and E(1)(slope) of all rats remained unchanged at the two time points. For second wash-in phase, E(2)(max) and E(2)(slope) of control rats remained unchanged, while with ovariectomized rats, E(2)(max) showed reduction at 8 weeks (4.5%±5.6%) compared to baseline (10.3%±6.3%, P=.037), and E(2)(slope) was lower at 8 weeks (0.015±0.017) than the baseline (0.029±0.022), although it was not statistically significant (P=.101).
  
  
  CONCLUSIONS
  Ovariectomy induced detectable decrease in second wash-in phase of contrast agent into lumbar disc.
authors.affiliation: Department of Imaging and Interventional Radiology, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, People's Republic of China.
authors.forename: Min
authors.initials: M
authors.lastname: Deng
authors.forename: James F
authors.initials: JF
authors.lastname: Griffith
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Zhu
authors.forename: Wai S
authors.initials: WS
authors.lastname: Poon
authors.forename: Anil T
authors.initials: AT
authors.lastname: Ahuja
authors.forename: Yi-Xiang J
authors.initials: YX
authors.lastname: Wang
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000493:pharmacokinetics; D005260:Female; D006571:Heterocyclic Compounds / Q000493:pharmacokinetics*; D007403:Intervertebral Disc / Q000378:metabolism* / Q000473:pathology*; D008159:Lumbar Vertebrae / Q000378:metabolism / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008657:Metabolic Clearance Rate; D009942:Organometallic Compounds / Q000493:pharmacokinetics*; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution
chemical_list: D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C050823:gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate