Effectively measuring exercise-related variations in T1ρ and T2 relaxation times of healthy articular cartilage

Dimitri A. Kessler, James W. MacKay, Scott McDonald, Stephen McDonnell, Andrew J. Grainger, Alexandra R. Roberts, Robert L. Janiczek, Martin J. Graves, Joshua D. Kaggie, Fiona J. Gilbert

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Background: Determining the compositional response of articular cartilage to dynamic joint-loading using MRI may be a more sensitive assessment of cartilage status than conventional static imaging. However, distinguishing the effects of joint-loading vs. inherent measurement variability remains difficult, as the repeatability of these quantitative methods is often not assessed or reported. Purpose: To assess exercise-induced changes in femoral, tibial, and patellar articular cartilage composition and compare these against measurement repeatability. Study Type: Prospective observational study. Population: Phantom and 19 healthy participants. Field Strength/Sequence: 3T; 3D fat-saturated spoiled gradient recalled-echo; T- and T2-prepared pseudosteady-state 3D fast spin echo. Assessment: The intrasessional repeatability of T and T2 relaxation mapping, with and without knee repositioning between two successive measurements, was determined in 10 knees. T and T2 relaxation mapping of nine knees was performed before and at multiple timepoints after a 5-minute repeated, joint-loading stepping activity. 3D surface models were created from patellar, femoral, and tibial articular cartilage. Statistical Tests: Repeatability was assessed using root-mean-squared-CV (RMS-CV). Using Bland–Altman analysis, thresholds defined as the smallest detectable difference (SDD) were determined from the repeatability data with knee repositioning. Results: Without knee repositioning, both surface-averaged T and T2 were very repeatable on all cartilage surfaces, with RMS-CV <1.1%. Repositioning of the knee had the greatest effect on T of patellar cartilage with the surface-averaged RMS-CV = 4.8%. While T showed the greatest response to exercise at the patellofemoral cartilage region, the largest changes in T2 were determined in the lateral femorotibial region. Following thresholding, significant (>SDD) average exercise-induced in T and T2 of femoral (–8.0% and –5.3%), lateral tibial (–6.9% and –5.9%), medial tibial (+5.8% and +2.9%), and patellar (–7.9% and +2.8%) cartilage were observed. Data Conclusion: Joint-loading with a stepping activity resulted in T and T2 changes above background measurement error. Evidence Level: 2. Technical Efficacy Stage: 1.

Original languageEnglish
Pages (from-to)1753-1764
Number of pages12
JournalJournal of Magnetic Resonance Imaging
Issue number6
Early online date16 Jul 2020
Publication statusPublished - Dec 2020


  • articular cartilage
  • exercise
  • MRI
  • quantitative imaging
  • relaxation time
  • repeatability

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