title: In vivo comparison of delayed gadolinium-enhanced MRI of cartilage and delayed quantitative CT arthrography in imaging of articular cartilage.
abstract: OBJECTIVE
  To compare delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) and delayed quantitative computed tomography (CT) arthrography (dQCTA) to each other, and their association to arthroscopy. Additionally, the relationship between dGEMRIC with intravenous (dGEMRIC(IV)) and intra-articular contrast agent administration (dGEMRIC(IA)) was determined.
  
  
  METHODS
  Eleven patients with knee pain were scanned at 3 T MRI and 64-slice CT before arthroscopy. dQCTA was performed at 5 and 45 min after intra-articular injection of ioxaglate. Both dGEMRIC(IV) and dGEMRIC(IA) were performed at 90 min after gadopentetate injection. dGEMRIC indices and change in relaxation rates (ΔR(1)) were separately calculated for dGEMRIC(IV) and dGEMRIC(IA). dGEMRIC and dQCTA parameters were calculated for predetermined sites at the knee joint that were International Cartilage Repair Society (ICRS) graded in arthroscopy.
  
  
  RESULTS
  dQCTA normalized with the contrast agent concentration in synovial fluid (SF) and dGEMRIC(IV) correlated significantly, whereas dGEMRIC(IA) correlated with the normalized dQCTA only when dGEMRIC(IA) was also normalized with the contrast agent concentration in SF. Correlation was strongest between normalized dQCTA at 45 min and ΔR(1,IV) (r(s) = 0.72 [95% CI 0.56-0.83], n = 49, P < 0.01) and ΔR(1,IA) normalized with ΔR(1) in SF (r(s) = 0.70 [0.53-0.82], n = 52, P < 0.01). Neither dGEMRIC nor dQCTA correlated with arthroscopic grading. dGEMRIC(IV) and non-normalized dGEMRIC(IA) were not related while ΔR(1,IV) correlated with normalized ΔR(1,IA) (r(s) = 0.52 [0.28-0.70], n = 50, P < 0.01).
  
  
  CONCLUSIONS
  This study suggests that dQCTA is in best agreement with dGEMRIC(IV) at 45 min after CT contrast agent injection. dQCTA and dGEMRIC were not related to arthroscopy, probably because the remaining cartilage is analysed in dGEMRIC and dQCTA, whereas in arthroscopy the absence of cartilage defines the grading. The findings indicate the importance to take into account the contrast agent concentration in SF in dQCTA and dGEMRIC(IA).
authors.affiliation: Department of Medical Technology, University of Oulu, Oulu, Finland. jukka.hirvasniemi@oulu.fi
authors.forename: J
authors.initials: J
authors.lastname: Hirvasniemi
authors.forename: K A M
authors.initials: KA
authors.lastname: Kulmala
authors.forename: E
authors.initials: E
authors.lastname: Lammentausta
authors.forename: R
authors.initials: R
authors.lastname: Ojala
authors.forename: P
authors.initials: P
authors.lastname: Lehenkari
authors.forename: A
authors.initials: A
authors.lastname: Kamel
authors.forename: J S
authors.initials: JS
authors.lastname: Jurvelin
authors.forename: J
authors.initials: J
authors.lastname: Töyräs
authors.forename: M T
authors.initials: MT
authors.lastname: Nieminen
authors.forename: S
authors.initials: S
authors.lastname: Saarakkala
mesh_terms: D000328:Adult; D000368:Aged; D001175:Arthrography / Q000379:methods*; D001182:Arthroscopy; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage; D006801:Humans; D007270:Injections, Intra-Articular; D007275:Injections, Intravenous; D007485:Ioxaglic Acid; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA; D007485:Ioxaglic Acid