title: Comparison of T1ρ, dGEMRIC, and quantitative T2 MRI in preoperative ACL rupture patients.
abstract: OBJECTIVE
  T1ρ, inversion recovery sequence with a gadolinium contrast agent (dGEMRIC), and T2 mapping have shown sensitivity toward different osteoarthritic-associated compositional changes after joint injury, but have not been studied concomitantly in vivo. We hypothesized that these magnetic resonance imaging sequences can be used to measure early glycosaminoglycan (GAG) losses and collagen disruption in cartilage of anterior cruciate ligament (ACL) rupture patients.
  
  
  METHODS
  Thirteen acute ACL rupture patients were each imaged during a 4-hour presurgery workup to acquire a fast-spin-echo-based T1ρ sequence, a multi-echo spin-echo T2 sequence, and T1-weighted dGEMRIC an average of 55.7 days after injury. After acquisition, the three sequences' relaxation times were analytically compared.
  
  
  RESULTS
  Site-specific differences were evinced, but nonsignificant differences in mean relaxation time between layers of the same region and sequence were observed (analysis of variance, P < .05). Spearman's correlation coefficients of 0.542 (T1ρ vs. T2, P < .05), -0.026 (T1ρ vs. dGEMRIC, P = .585) and -0.095 (T2 vs. dGEMRIC, P < .05) were found.
  
  
  CONCLUSIONS
  No appreciable focal GAG loss was detected by dGEMRIC, and T2 was generally elevated in the early acute phase of blunt trauma injury. In contrast, both general and focal elevations in T1ρ relaxation times were identified, indicating an acute increase in unbound water in the matrix after blunt trauma, and show that patient-specific cartilage changes occur within otherwise healthy, young patients. Further investigation into each sequence's long-term significance is warranted to help clinicians decide which sequence(s) will be the most useful for osteoarthritis prognosis given the challenge of concomitantly acquiring all three in a busy clinical setting.
authors.affiliation: Department of Orthopaedics and Rehabilitation, The University of Iowa, Iowa City, IA 52242-1100, USA.
authors.forename: Noelle F
authors.initials: NF
authors.lastname: Klocke
authors.forename: Annunziato
authors.initials: A
authors.lastname: Amendola
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Thedens
authors.forename: Glenn N
authors.initials: GN
authors.lastname: Williams
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Luty
authors.forename: James A
authors.initials: JA
authors.lastname: Martin
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Pedersen
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D016118:Anterior Cruciate Ligament / Q000378:metabolism* / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D002358:Cartilage, Articular / Q000378:metabolism; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006025:Glycosaminoglycans / Q000378:metabolism; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male
chemical_list: D003287:Contrast Media; D006025:Glycosaminoglycans; D019786:Gadolinium DTPA