Transverse relaxation mechanisms in articular cartilage

Mlynarik, Vladimir; Szomolányi, Pavol; Toffanin, Renato; Vittur, Franco; Trattnig, Siegfried

doi:10.1016/j.jmr.2004.05.003

Cited by 127 publications

(137 citation statements)

References 28 publications

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“…The contrast agent Gd-DTPA not only dominates the water relaxation, it also dampens the T 2 and T 1 relaxation times. Mlynarik et al (19) also reported that the relaxation mechanisms (T 2 and T 1 ) in articular cartilage are dependent on the static magnetic field (2.95T and 7.05T). Their studies also suggested that the dipolar relaxation was the dominant contribution at low field strengths (Ͻ3T), and that chemical exchange between OH and NH groups of PG with bulk water was the dominant relaxation mechanism at high fields (Ͼ3T).…”

Section: Discussionmentioning

confidence: 97%

“…However, studies that employ enzymatic treatment of excised tissue may not reliably mimic longterm degenerative changes in human OA. In contrast to previous studies (19,20), in the current study we aimed to measure T 1 relaxation in human cartilage specimens obtained from surgical replacement of knee joints. Recent in vitro and in vivo studies on cartilage have demonstrated that the T 1 is sensitive to changes in the PG content of cartilage (7,8,21).…”

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confidence: 99%

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T_1ρ relaxation mapping in human osteoarthritis (OA) cartilage: Comparison of T_1ρ with T₂

Regatte

Akella

Lonner

et al. 2006

Magnetic Resonance Imaging

293

298

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Purpose:To quantify the spin-lattice relaxation time in the rotating frame (T 1 ) in various clinical grades of human osteoarthritis (OA) cartilage specimens obtained from total knee replacement surgery, and to correlate the T 1 with OA disease progression and compare it with the transverse relaxation time (T 2 ). Materials and Methods:Human cartilage specimens were obtained from consenting patients (N ϭ 8) who underwent total replacement of the knee joint at the Pennsylvania Hospital, Philadelphia, PA, USA. T 2 -and T 1 -weighted images were obtained on a 4.0 Tesla whole-body GE Signa scanner (GEMS, Milwaukee, WI, USA). A 7-cm diameter transmit/receive quadrature birdcage coil tuned to 170 MHz was employed.Results: All of the surgical knee replacement OA cartilage specimens showed elevated relaxation times (T 2 and T 1 ) compared to healthy cartilage tissue. In various grades of OA specimens, the T 1 relaxation times varied from 62 Ϯ 5 msec to 100 Ϯ 8 msec (mean Ϯ SEM) depending on the degree of cartilage degeneration. However, T 2 relaxation times varied only from 32 Ϯ 2 msec to 45 Ϯ 4 msec (mean Ϯ SEM) on the same cartilage specimens. The increase in T 2 and T 1 in various clinical grades of OA specimens were ϳ5-50% and 30 -120%, respectively, compared to healthy specimens. The degenerative status of the cartilage specimens was also confirmed by histological evaluation. Conclusion:Preliminary results from a limited number of knee specimens (N ϭ 8) suggest that T 1 relaxation mapping is a sensitive noninvasive marker for quantitatively predicting and monitoring the status of macromolecules in early OA. Furthermore, T 1 has a higher dynamic range (Ͼ100%) for detecting early pathology compared to T 2 . This higher dynamic range can be exploited to measure even small macromolecular changes with greater accuracy compared to T 2 . Because of these advantages, T 1 relaxation mapping may be useful for evaluating early OA therapy.

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Section: Discussionmentioning

confidence: 97%

mentioning

confidence: 99%

T_1ρ relaxation mapping in human osteoarthritis (OA) cartilage: Comparison of T_1ρ with T₂

Regatte

Akella

Lonner

et al. 2006

Magnetic Resonance Imaging

293

298

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“…Additionally, a recent study found that T 1r and GAG content can be correlated in the deeper zones but not in the upper half of cartilage [109]. While the exact contributions of water, proteoglycans and collagen to T 1r have yet to be determined [110], proteoglycan depletion does result in an increase in T 1r [50,51,106,111]. Additionally, studies have shown that T 1r tends to reflect depth-dependent trends in T 2 [33], with the highest T 1r values at the superficial tangential zone and decreasing values reaching a minimum at either the middle zone [28,51] or the deep zone [33,110].…”

Section: T 1r Mappingmentioning

confidence: 98%

“…While the exact contributions of water, proteoglycans and collagen to T 1r have yet to be determined [110], proteoglycan depletion does result in an increase in T 1r [50,51,106,111]. Additionally, studies have shown that T 1r tends to reflect depth-dependent trends in T 2 [33], with the highest T 1r values at the superficial tangential zone and decreasing values reaching a minimum at either the middle zone [28,51] or the deep zone [33,110]. Although the exact relationship of T 1r to proteoglycan or other biochemical content in articular cartilage remains unclear [55,107], T 1r mapping is gaining momentum as a viable technique for imaging of cartilage biochemistry.…”

Section: T 1r Mappingmentioning

confidence: 99%

Probing articular cartilage damage and disease by quantitative magnetic resonance imaging

Chan

Neu

2013

J. R. Soc. Interface.

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Osteoarthritis (OA) is a debilitating disease that reflects a complex interplay of biochemical, biomechanical, metabolic and genetic factors, which are often triggered by injury, and mediated by inflammation, catabolic cytokines and enzymes. An unmet clinical need is the lack of reliable methods that are able to probe the pathogenesis of early OA when disease-rectifying therapies may be most effective. Non-invasive quantitative magnetic resonance imaging (qMRI) techniques have shown potential for characterizing the structural, biochemical and mechanical changes that occur with cartilage degeneration. In this paper, we review the background in articular cartilage and OA as it pertains to conventional MRI and qMRI techniques. We then discuss how conventional MRI and qMRI techniques are used in clinical and research environments to evaluate biochemical and mechanical changes associated with degeneration. Some qMRI techniques allow for the use of relaxometry values as indirect biomarkers for cartilage components. Direct characterization of mechanical behaviour of cartilage is possible via other specialized qMRI techniques. The combination of these qMRI techniques has the potential to fully characterize the biochemical and biomechanical states that represent the initial changes associated with cartilage degeneration. Additionally, knowledge of in vivo cartilage biochemistry and mechanical behaviour in healthy subjects and across a spectrum of osteoarthritic patients could lead to improvements in the detection, management and treatment of OA.

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“…In the last 10 years, the T 2 of articular cartilage has attracted much attention due to its ability to detect changes in the collagen matrix (1)(2)(3)(4)(5). Significantly increased T 2 in articular cartilage of patients with osteoarthritis has been observed globally (1) and locally in focal lesions (6).…”

mentioning

confidence: 99%

T₂ measurement in articular cartilage: Impact of the fitting method on accuracy and precision at low SNR

Raya

Dietrich

Horng

et al. 2009

Magnetic Resonance in Med

135

187

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T 2 relaxation time is a promising MRI parameter for the detection of cartilage degeneration in osteoarthritis. However, the accuracy and precision of the measured T 2 may be substantially impaired by the low signal-to-noise ratio of images available from clinical examinations. The purpose of this work was to assess the accuracy and precision of the traditional fit methods (linear least-squares regression and nonlinear fit to an exponential) and two new noise-corrected fit methods: fit to a noisecorrected exponential and fit of the noise-corrected squared signal intensity to an exponential. Accuracy and precision have been analyzed in simulations, in phantom measurements, and in seven repetitive acquisitions of the patellar cartilage in six healthy volunteers. Traditional fit methods lead to a poor accuracy for low T 2 , with overestimations of the exact T 2 up to 500%. The noise-corrected fit methods demonstrate a very good accuracy for all T 2 values and signal-to-noise ratio. Even more, the fit to a noise-corrected exponential results in precisions comparable to the best achievable precisions (Cramér-Rao lower bound). For in vivo images, the traditional fit methods considerably overestimate T 2 near the bone-cartilage interface. Therefore, using an adequate fit method may substantially improve the sensitivity of T 2 to detect pathology in cartilage and change in T 2 follow-up examinations. Magn Reson Med 63:181-193, 2010.

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Transverse relaxation mechanisms in articular cartilage

Cited by 127 publications

References 28 publications

T_1ρ relaxation mapping in human osteoarthritis (OA) cartilage: Comparison of T_1ρ with T₂

T_1ρ relaxation mapping in human osteoarthritis (OA) cartilage: Comparison of T_1ρ with T₂

Probing articular cartilage damage and disease by quantitative magnetic resonance imaging

T₂ measurement in articular cartilage: Impact of the fitting method on accuracy and precision at low SNR

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Transverse relaxation mechanisms in articular cartilage

Cited by 127 publications

References 28 publications

T1ρ relaxation mapping in human osteoarthritis (OA) cartilage: Comparison of T1ρ with T2

T1ρ relaxation mapping in human osteoarthritis (OA) cartilage: Comparison of T1ρ with T2

Probing articular cartilage damage and disease by quantitative magnetic resonance imaging

T2 measurement in articular cartilage: Impact of the fitting method on accuracy and precision at low SNR

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T_1ρ relaxation mapping in human osteoarthritis (OA) cartilage: Comparison of T_1ρ with T₂

T_1ρ relaxation mapping in human osteoarthritis (OA) cartilage: Comparison of T_1ρ with T₂

T₂ measurement in articular cartilage: Impact of the fitting method on accuracy and precision at low SNR