T1rho MRI of menisci and cartilage in patients with osteoarthritis at 3T

Abstract

Objective: To assess and compare subregional and whole T1rho values (median±interquartile range) of femorotibial cartilage and menisci in patients with doubtful (Kellgren-Lawrence (KL) grade 1) to severe (KL4) osteoarthritis (OA) at 3T.

Materials and methods: 30 subjects with varying degrees of OA (KL1-4, 13 females, 17 males, mean age±SD=63.9±13.1 years) were evaluated on a 3T MR scanner using a spin-lock-based 3D GRE sequence for T1rho mapping. Clinical proton density (PD)-weighted fast spin echo (FSE) images in sagittal (without fat saturation), axial, and coronal (fat-saturated) planes were acquired for cartilage and meniscus Whole-organ MR imaging score (WORMS) grading. Wilcoxon rank sum test was performed to determine whether there were any statistically significant differences between subregional and whole T1rho values of femorotibial cartilage and menisci in subjects with doubtful to severe OA.

Results: Lateral (72±10 ms, median±interquartile range) and medial (65±10 ms) femoral anterior cartilage subregions in moderate-severe OA subjects had significantly higher T1rho values (P<0.05) than cartilage subregions and whole femorotibial cartilage in doubtful-minimal OA subjects. There were statistically significant differences in meniscus T1rho values of the medial posterior subregion of subjects with moderate-severe OA and T1rho values of all subregions and the whole meniscus in subjects with doubtful-minimal OA. When evaluated based on WORMS, statistically significant differences were identified in T1rho values between the lateral femoral anterior cartilage subregion in patients with WORMS5-6 (advanced degeneration) and whole femorotibial cartilage and all cartilage subregions in patients with WORMS0-1 (normal).

Conclusion: T1rho values are higher in specific meniscus and femorotibial cartilage subregions. These findings suggest that regional damage of both femorotibial hyaline cartilage and menisci may be associated with osteoarthritis.

Fig. 1

Representative cartilage images from normal cartilage to severe cartilage degeneration based on WORMS grading. Arrows mark the location of cartilage lesions. WORMS = 0 for all regions, a) coronal proton density (PD)-weighted FSE fat-saturated, b) lateral and c) medial sagittal PD-weighted without fat saturation; WORMS = 1 for lateral patellar facet, d) axial PD-weighted FSE fat-saturated; WORMS = 2 for medial posterior tibial plateau, e) sagittal PD-weighted without fat saturation; WORMS = 2.5 for medial femoral condyle, f) coronal PD-weighted FSE fat-saturated, g) sagittal PD-weighted without fat saturation; WORMS = 4 for medial femoral central condyle, h) coronal PD-weighted FSE fat-saturated, i) sagittal PD-weighted without fat saturation; WORMS = 5 for lateral patellar facet, j) axial PD-weighted FSE fat-saturated; WORMS = 5 for medial tibial anterior plateau, k) coronal PD-weighted FSE fat-saturated; WORMS = 6 for central tibial plateau, l) coronal PD-weighted FSE fat-saturated, m) sagittal PD-weighted without fat saturation; WORMS = 6 for lateral tibial plateau, n) sagittal PD-weighted without fat saturation.

Fig. 2

Representative meniscus images from normal meniscus to severe meniscus degeneration based on WORMS grading. Arrows mark the location of meniscus lesions. WORMS = 0 for lateral meniscus, a) coronal proton density (PD)-weighted FSE fat-saturated, b) sagittal PD-weighted without fat saturation; WORMS = 1 for medial posterior horn, c) sagittal PD-weighted without fat saturation; WORMS = 2 for medial posterior horn: radial tear, d) coronal PD-weighted FSE fat-saturated; WORMS = 3 for non-displaced tear of medial posterior horn, e) sagittal PD-weighted without fat saturation; WORMS = 3 for surgical partial repair medial posterior horn, f) sagittal PD-weighted without fat saturation; WORMS = 6 for medial central, g) coronal PD-weighted FSE fat-saturated; WORMS = 6 for medial posterior horn, h) sagittal PD-weighted without fat saturation; WORMS = 6 for complete resection medially, i) sagittal PD-weighted without fat saturation.

Fig. 3

Representative T1rho maps of cartilage in the lateral (a) and medial (b) compartments, and T1rho maps of menisci in the lateral (c, d) and medial (e, f) compartments, respectively, obtained from a doubtful-minimal OA patient. The color bars on the right show the T1rho values ranges, respectively. The different barscale ranges can display the respective T1rho values distribution of cartilage and meniscus more effectively.

Fig. 4

Box and whisker plots of cartilage T1rho values (median ± interquartile range) in the different cartilage subregions and for whole cartilage based on different K–L grades (a) and different WORMS grades (b). The box and whisker plot shows the five statistics (minimum, first quartiles, median, third quartiles, and maximum). Fig. 4(a) $ Significantly different (P < 0.05) between LFa with KL3–4 and all other cartilage subregions and whole femorotibial cartilage with KL1–2 except MFa with KL1–2. * Significantly different (P < 0.05) between MFa with KL3–4 and all other cartilage subregions and whole femorotibial cartilage with KL1–2 except MFa with KL1–2. Fig. 4(b) & Significantly different (P < 0.05) between LFa with WORMS5–6 and all other cartilage subregions and whole femorotibial cartilage with WORMS0–1 except LFa with WORMS0–1. # Significantly different (P < 0.05) between MTp with WORMS grade 0–1 and all other cartilage subregions and whole femorotibial cartilage with WORMS grade 5–6 except LFc, LTc, MTa with WORMS grade 5–6. % Significantly different (P < 0.05) between LFa with WORMS grade 2–4 and all other cartilage subregions and whole femorotibial cartilage with WORMS grade 5–6 except LFa and MFa with WORMS grade 5–6. @ Significantly different (P < 0.05) between LFa with WORMS grade 5–6 and all other cartilage subregions and whole femorotibial cartilage with WORMS grade 2–4 except LFa and MFa with WORMS grade 2–4. ** Significantly different (P < 0.05) between MFa with WORMS grade 5–6 and all other cartilage subregions and whole femorotibial cartilage with WORMS grade 2–4 except LFa and MFa with WORMS grade 2–4.

Fig. 5

Box and whisker plots of meniscus T1rho values (median ± interquartile range) in the different meniscus subregions and for the whole meniscus based on different K–L grades (a) and different WORMS grades (b). Fig. 5(a) * Significantly different (P < 0.05) between Mp with KL3–4 and all other sub-regions and the whole meniscus with KL1–2 except Mp with KL1–2. Fig. 5(b) $ Significantly different (P < 0.05) between Ma with WORMS grade 2–4 and all other sub-regions and the whole meniscus with WORMS grade 0–1 except Ma with WORMS grade 0–1. # Significantly different (P < 0.05) between Ma with WORMS grade 2–4 and all other sub-regions and the whole meniscus with WORMS grade 5–6 except Lc with WORMS grade 5–6.