title: In vivo transport of Gd-DTPA(2-)  in human knee cartilage assessed by depth-wise dGEMRIC analysis.
abstract: OBJECTIVE
  To investigate the transport of Gd-DTPA(2-) in different layers of femoral knee cartilage in vivo.
  
  
  METHODS
  T(1) measurements (1.5 Tesla) were performed in femoral knee cartilage of 23 healthy volunteers. The weight-bearing central cartilage was analyzed before contrast and at eight time points after an intravenous injection of Gd-DTPA(2-) : 12-60 min (4 volunteers) and 1-4 h (19 volunteers). Three regions of interest were segmented manually: deep, middle, and superficial.
  
  
  RESULTS
  Before contrast injection, a depth-wise variation of T(1) was observed with 50% higher values in the superficial region compared with the deep region. In the deep region, the uptake of Gd-DTPA(2-) was not detected until 36 min and the concentration increased until 240 min, whereas in the superficial region, the uptake was seen already at 12 min and the concentration decreased after 180 min (P < 0.01). There was a difference between medial and lateral compartment regarding bulk, but not superficial Gd-DTPA(2-) concentration. The bulk gadolinium concentration was negatively related to the cartilage thickness (r = -0.68; P < 0.01).
  
  
  CONCLUSIONS
  The depth-wise and thickness dependent variations in Gd-DTPA(2) transport influence the interpretation of bulk dGEMRIC analysis in vivo. In thick cartilage, incomplete penetration of Gd-DTPA(2) will yield a falsely too long T(1) .
authors.affiliation: Joint and Soft Tissue Unit, Department of Clinical Sciences, Lund University, Malmö, Sweden.
authors.forename: Zana K
authors.initials: ZK
authors.lastname: Hawezi
authors.forename: Eveliina
authors.initials: E
authors.lastname: Lammentausta
authors.forename: Jonas
authors.initials: J
authors.lastname: Svensson
authors.forename: Leif E
authors.initials: LE
authors.lastname: Dahlberg
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Tiderius
mesh_terms: D000328:Adult; D001692:Biological Transport; D002358:Cartilage, Articular / Q000033:anatomy & histology / Q000378:metabolism*; D003287:Contrast Media / Q000493:pharmacokinetics*; D005260:Female; D019786:Gadolinium DTPA / Q000493:pharmacokinetics*; D006801:Humans; D007719:Knee Joint; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016474:Weight-Bearing
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA