Composite metric R2 − R (1/T2 − 1/T) as a potential MR imaging biomarker associated with changes in pain after ACL reconstruction: A six-month follow-up

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10 Scopus citations


This study looked to investigate a new quantitative metric, R2 − R (1/T2 − 1/T), using magnetic resonance (MR) images and voxel-based relaxometry (VBR) for detecting early cartilage degeneration and explore the association with patient-reported outcomes measures (PROMs) in patients 6 months after ACL reconstruction. Sixty-four patients from three sites were bilaterally scanned on a 3T MR with a combined T/T2 protocol to calculate R (1/T) and R2 (1/T2) values at baseline and 6 months after reconstructive surgery. Non-rigid registration was applied to align images onto a template, allowing VBR to determine VBR rate differences and explore cross-sectional and longitudinal differences between injured and uninjured knees, generating Statistical Parametric Maps (SPMs). Baseline R2 − R differences were further correlated with change in PROMs from the Knee Injury and Osteoarthritis Outcome Score (KOOS) from baseline to 6 months. Cross-sectional results demonstrated low relaxation rate differences in the injured patella (baseline: 21%, p = 0.01; 6-months: 18%, p = 0.02), lateral tibia (baseline: 25%, p = 0.01; 6-months: 24%, p = 0.01), and weight-bearing regions of the tibia and femur. The uninjured patella showed significant longitudinal changes (17%, p = 0.02). R2 − R differences showed significant correlations with KOOS PROMs, particularly in the lateral tibia, patella, and trochlea. R2 − R difference VBR analyses provide new and highly sensitive parameters for assessing early cartilage degeneration in patients after ACL injury by integrating findings from both T and T2, commonly used relaxation time parameters, into a single metric.

Original languageEnglish (US)
Pages (from-to)718-729
Number of pages12
JournalJournal of Orthopaedic Research
Issue number3
StatePublished - Mar 1 2017
Externally publishedYes


  • ACL injury
  • KOOS
  • R – R
  • cartilage degeneration
  • voxel-based relaxometry

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine


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