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Purpose: To evaluate in vivo T2 mapping as quantitative, imaging-based biomarker for meniscal degeneration in humans, by studying the correlation between T2 relaxation time and degree of histological degeneration as reference standard.Methods: In this prospective validation study, 13 menisci from seven patients with radiographic knee osteoarthritis (median age 67 years, three males) were included. Menisci were obtained during total knee replacement surgery. All patients underwent pre-operative magnetic resonance imaging using a 3-T MR scanner which included a T2 mapping pulse sequence with multiple echoes. Histological analysis of the collected menisci was performed using the Pauli score, involving surface integrity, cellularity, matrix organization, and staining intensity. Mean T2 relaxation times were calculated in meniscal regions of interest corresponding with the areas scored histologically, using a multi-slice multi-echo postprocessing algorithm. Correlation between T2 mapping and histology was assessed using a generalized least squares model fit by maximum likelihood.Results: The mean T2 relaxation time was 22.4 ± 2.7 ms (range 18.5-27). The median histological score was 10, IQR 7-11 (range 4-13). A strong correlation between T2 relaxation time and histological score was found (rs = 0.84, CI 95% 0.64-0.93).Conclusion: In vivo T2 mapping of the human meniscus correlates strongly with histological degeneration, suggesting that T2 mapping enables the detection and quantification of early compositional changes of the meniscus in knee OA.Key Points: • Prospective histology-based study showed that in vivo T 2 mapping of the human meniscus correlates strongly with histological degeneration. • Meniscal T 2 mapping allows detection and quantifying of compositional changes, without need for contrast or special MRI hardware. • Meniscal T 2 mapping provides a biomarker for early OA, potentially allowing early treatment strategies and prevention of OA progression. [ABSTRACT FROM AUTHOR]

Objectives: To assess (1) whether normal and degenerated menisci exhibit different T1 on delayed gadolinium-enhanced MRI of the meniscus (dGEMRIM), (2) the reproducibility of dGEMRIM and (3) the correlation between meniscus and cartilage T1 in knee osteoarthritis (OA) patients. Methods: In 17 OA patients who underwent dGEMRIM twice within 7 days, meniscus and cartilage T1 was calculated. Meniscus pathology was evaluated on conventional MRI. T1 in normal and degenerated menisci were compared using a Student's t-test. Reproducibility was assessed using ICCs. Pearson's correlation was calculated between meniscus and cartilage T1. Results: A trend towards lower T1 in degenerated menisci (mean: 402 ms; 95 % CI: 359-444 ms) compared to normal menisci (mean: 448 ms; 95 % CI: 423-473 ms) was observed ( p = 0.05). Meniscus T1 ICCs were 0.85-0.90. The correlation between meniscus and cartilage T1 was moderate in the lateral ( r = 0.52-0.75) and strong in the medial compartment ( r = 0.78-0.94). Conclusions: Our results show that degenerated menisci have a clear trend towards lower T1 compared to normal menisci. Since these results are highly reproducible, meniscus degeneration may be assessed within one delayed gadolinium-enhanced MRI simultaneously with cartilage. The strong correlation between meniscus and cartilage T1 suggests concomitant degeneration in both tissues in OA, but also suggests that dGEMRIC may not be regarded entirely as sulphated glycosaminoglycan specific. Key Points: • dGEMRIM T1 can possibly be used to assess meniscal degeneration; • dGEMRIM yields highly reproducible meniscal T1 in early stage osteoarthritic patients; • Concomitant degeneration of cartilage and meniscus tissue occurs in early stage osteoarthritis; • dGEMRIC cannot be regarded as entirely sulphated glycosaminoglycan specific. [ABSTRACT FROM AUTHOR]