Cartilage and meniscal T2 relaxation time as non-invasive biomarker for knee osteoarthritis and cartilage repair procedures

Abstract

Objective: The purpose of this work was to review the current literature on cartilage and meniscal T2 relaxation time.

Methods: Electronic searches in PubMed were performed to identify relevant studies about T2 relaxation time measurements as non-invasive biomarker for knee osteoarthritis (OA) and cartilage repair procedures.

Results: Initial osteoarthritic changes include proteoglycan loss, deterioration of the collagen network, and increased water content within the articular cartilage and menisci. T2 relaxation time measurements are affected by these pathophysiological processes. It was demonstrated that cartilage and meniscal T2 relaxation time values were significantly increased in subjects with compared to those without radiographic OA and focal knee lesions, respectively. Subjects with OA risk factors such as overweight/obesity showed significantly greater cartilage T2 values than normal controls. Elevated cartilage and meniscal T2 relaxation times were found in subjects with vs without knee pain. Increased cartilage T2 at baseline predicted morphologic degeneration in the cartilage, meniscus, and bone marrow over 3 years. Furthermore, cartilage repair tissue could be non-invasively assessed by using T2 mapping. Reproducibility errors for T2 measurements were reported to be smaller than the T2 differences in healthy and diseased cartilage indicating that T2 relaxation time may be a reliable discriminatory biomarker.

Conclusions: Cartilage and meniscal T2 mapping may be suitable as non-invasive biomarker to diagnose early stages of knee OA and to monitor therapy of OA.

Keywords: Cartilage and meniscal T2 relaxation time; Knee; Magnetic resonance imaging; Osteoarthritis.

Fig. 1

Representative color-coded, sagittal T2 maps with segmented PAT, TRO, LF, and LT compartments in A, and MF and MT compartments in B. A sagittal 2D MSME SE sequence was used for T2 mapping (TR of 2700 m; seven TEs of 10 ms, 20 ms, 30 ms, 40 ms, 50 ms, 60 ms, and 70 ms; slice thickness of 3 mm with 0.5 mm gap, in-plane spatial resolution of 0.313 × 0.446 mm², acquisition time of 10.6 min).

Fig. 2

Representative color-coded, sagittal T2 maps with segmented anterior horn (AH) and posterior horn (PH) of the medial meniscus in A, and segmented body of medial meniscus in B. A nonselective T2 preparation and a 3D SPGR acquisition during the transient signal evolving towards steady state was used for T2 mapping (TR of 2000 ms; four TEs of 4.1 ms, 14.5 ms, 25.0 ms, and 45.9 ms; slice thickness of 3 mm; in-plane spatial resolution of 0.547 × 0.729 mm², acquisition time of 10.6 min).

Fig. 3

Representative color-coded, sagittal T2 maps with segmented MF and MT compartments of a normal control (A) and a subject with the OA risk factor obesity (B). Note the elevated cartilage T2 values in the obese subject compared to the normal control. A sagittal 2D multi-slice multi-echo (MSME) SE sequence was used for T2 mapping (TR of 2700 m; seven TEs of 10 ms, 20 ms, 30 ms, 40 ms, 50 ms, 60 ms, and 70 ms; slice thickness of 3 mm with 0.5 mm gap, in-plane spatial resolution of 0.313 × 0.446 mm², acquisition time of 10.6 min).