Feasibility study for evaluating early lumbar facet joint degeneration using axial T 1ρ, T 2, and T2* mapping in cartilage: Evaluating Early LFJ Degeneration

PURPOSE: To assess the feasibility of axial T2 , T2*, and T1 ρ mapping of lumbar facet joint (LFJ) cartilage for evaluation of early degeneration. MATERIALS AND METHODS: We examined a total of 176 LFJs from 21 volunteers using axial T2 , T2*, and T1 ρ mapping with a 3.0T magnetic resonance imaging (MRI) scanner. All LFJs were measured and grouped according to the presence of low back pain (LBP), the Weishaupt grading system, and the Pfirrmann grade of the adjacent intervertebral disk (IVD). T2 , T2*, and T1 ρ values were analyzed and compared among the different groups. RESULTS: Low interobserver agreement was found in the Weishaupt grading of LFJs (κ = 0.161). The T1 ρ values of LFJs were significantly different between adjacent two Pfirrmann grade of disks (grade I 50.15 ± 3.63 msec / grade II 53.27 ± 3.80 msec, P = 0.002; grade II 53.27 ± 3.80 msec / grade III 58.40 ± 4.17 msec, P < 0.01), and in different Weishaupt grades of LFJs (P = 0.000). T2* values were only found significantly different between Pfirrmann grade I and III of disks (P = 0.048). There was no significant difference in T2 values of LFJs whatever in Pfirrmann (P = 0.556) or Weishaupt grades (P = 0.694). No significant difference was found in T2 , T2*, and T1 ρ values between volunteers with LBP and without LBP (PT2  = 0.783, PT2*=0.311, PT1 ρ = 0.259). CONCLUSION: Axial T1 ρ could be an effective and sensitive method to assess for early degenerative changes in LFJ cartilage. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:468-475.