T1-weighted sodium MRI of the articulator cartilage in osteoarthritis: a cross sectional and longitudinal study

Insights into the Age Dependency of Compositional MR Biomarkers Quantifying the Health Status of Cartilage in Metacarpophalangeal Joints

(1) Background: We aim to investigate age-related changes in cartilage structure and composition in the metacarpophalangeal (MCP) joints using magnetic resonance (MR) biomarkers. (2) Methods: The cartilage tissue of 90 MCP joints from 30 volunteers without any signs of destruction or inflammation was examined using T1, T2, and T1ρ compositional MR imaging techniques on a 3 Tesla clinical scanner and correlated with age. (3) Results: The T1ρ and T2 relaxation times showed a significant correlation with age (T1ρ: Kendall-τ-b = 0.3, p < 0.001; T2: Kendall-τ-b = 0.2, p = 0.01). No significant correlation was observed for T1 as a function of age (T1: Kendall-τ-b = 0.12, p = 0.13). (4) Conclusions: Our data show an increase in T1ρ and T2 relaxation times with age. We hypothesize that this increase is due to age-related changes in cartilage structure and composition. In future examinations of cartilage using compositional MRI, especially T1ρ and T2 techniques, e.g., in patients with osteoarthritis or rheumatoid arthritis, the age of the patients should be taken into account.

Update: Posttreatment Imaging of the Knee after Cartilage Repair

Focal cartilage lesions are common pathologies at the knee joint that are considered important risk factors for the premature development of osteoarthritis. A wide range of surgical options, including but not limited to marrow stimulation, osteochondral auto- and allografting, and autologous chondrocyte implantation, allows for targeted treatment of focal cartilage defects. Arthroscopy is the standard of reference for the assessment of cartilage integrity and quality before and after repair. However, deep cartilage layers, intrachondral composition, and the subchondral bone are only partially or not at all visualized with arthroscopy. In contrast, magnetic resonance imaging offers noninvasive evaluation of the cartilage repair site, the subchondral bone, and the soft tissues of the joint pre- and postsurgery. Radiologists need to be familiar with the different surgical procedures available and their characteristic postsurgical imaging appearances to assess treatment success and possible complications adequately. We provide an overview of the most commonly performed surgical procedures for cartilage repair at the knee and typical postsurgical imaging characteristics.

Comprehensive Account of Sodium Imaging and Spectroscopy for Brain Research

Sodium (²³Na) is a vital component of neuronal cells and plays a key role in various signal transmission processes. Hence, information on sodium distribution in the brain using magnetic resonance imaging (MRI) provides useful information on neuronal health. ²³Na MRI and MR spectroscopy (MRS) improve the diagnosis, prognosis, and clinical monitoring of neurological diseases but confront some inherent limitations that lead to low signal-to-noise ratio, longer scan time, and diminished partial volume effects. Recent advancements in multinuclear MR technology have helped in further exploration in this domain. We aim to provide a comprehensive description of ²³Na MRI and MRS for brain research including the following aspects: (a) theoretical background for understanding ²³Na MRI and MRS fundamentals; (b) technological advancements of ²³Na MRI with respect to pulse sequences, RF coils, and sodium compartmentalization; (c) applications of ²³Na MRI in the early diagnosis and prognosis of various neurological disorders; (d) structural-chronological evolution of sodium spectroscopy in terms of its numerous applications in human studies; (e) the data-processing tools utilized in the quantitation of sodium in the respective anatomical regions.

Emerging role of integrated PET-MRI in osteoarthritis

Osteoarthritis (OA) is a common degenerative disorder of the articular cartilage, which is associated with hypertrophic changes in the bone, synovial inflammation, subchondral sclerosis, and joint space narrowing (JSN). Radiography remains the first line of imaging till now. Due to the lack of soft-tissue depiction in radiography, researchers are exploring various imaging techniques to detect OA at an early stage and understand its pathophysiology to restrict its progression and discover disease-modifying agents in OA. As the OA relates to the degradation of articular cartilage and remodeling of the underlying bone, an optimal imaging tool must be sensitive to the bone and soft tissue health. In that line, many non-invasive imaging and minimally invasive techniques have been explored. Out of these, the non-invasive compositional magnetic resonance imaging (MRI) for evaluation of the integrity of articular cartilage and positron emission tomography (PET) scan with fluorodeoxyglucose (FDG) and more specific bone-seeking tracer like sodium fluoride (18F-NaF) for bone cartilage interface are some of the leading areas of ongoing work. Integrated PET-MRI system, a new hybrid modality that combines the virtues of the above two individual modalities, allows detailed imaging of the entire joint, including soft tissue cartilage and bone, and holds great potential to research complex disease processes of OA. This narrative review attempts to signify individual characteristics of MRI, PET, the fusion of these characteristics in PET-MRI, and the ongoing research on PET-MRI as a potential tool to understand the pathophysiology of OA.

Assessment of Low-Grade Focal Cartilage Lesions in the Knee With Sodium MRI at 7 T: Reproducibility and Short-Term, 6-Month Follow-up Data

OBJECTIVES

Several articles have investigated potential of sodium (Na) magnetic resonance imaging (MRI) for the in vivo evaluation of cartilage health, but so far no study tested its feasibility for the evaluation of focal cartilage lesions of grade 1 or 2 as defined by the International Cartilage Repair Society. The aims of this study were to evaluate the ability of Na-MRI to differentiate between early focal lesions and normal-appearing cartilage, to evaluate within-subject reproducibility of Na-MRI, and to monitor longitudinal changes in participants with low-grade, focal chondral lesions.

MATERIALS AND METHODS

Thirteen participants (mean age, 50.1 ± 10.9 years; 7 women, 6 men) with low-grade, focal cartilage lesions in the weight-bearing region of femoral cartilage were included in this prospective cohort study. Participants were assessed at baseline, 1 week, 3 months, and 6 months using morphological MRI at 3 T and 7 T, compositional Na-MRI at 7 T, and the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire. Na signal intensities corrected for coil sensitivity and partial volume effect (Na-cSI) were calculated in the lesion, and in weight-bearing and non-weight-bearing regions of healthy femoral cartilage. Coefficients of variation, repeated measures analysis of covariance models, and Pearson correlation coefficients were calculated to evaluate within-subject reproducibility as well as cross-sectional and longitudinal changes in Na-cSI values.

RESULTS

The mean coefficients of variation of Na-cSI values between the baseline and 1-week follow-up were 5.1% or less in all cartilage regions. Significantly lower Na-cSI values were observed in lesion than in weight-bearing and non-weight-bearing regions at all time points (all P values ≤ 0.002). Although a significant decrease from baseline Na-cSI values in lesion was found at 3-month visit (P = 0.015), no substantial change was observed at 6 months. KOOS scores have improved in all subscales at 3 months and 6 months visit, with a significant increase observed only in the quality of life subscale (P = 0.004).

CONCLUSIONS

In vivo Na-MRI is a robust and reproducible method that allows to differentiate between low-grade, focal cartilage lesions and normal-appearing articular cartilage, which supports the concept that compositional cartilage changes can be found early, before the development of advanced morphological changes visible at clinical 3-T MRI.

Evaluation of distal femoral cartilage by B-mode ultrasonography and shear wave elastography in patients with knee osteoarthritis: a preliminary study

BACKGROUND

Degenerative change in articular cartilage is one of the most important factors in the development of osteoarthritis. Shear wave elastography can be used to identify pathologic cartilage.

PURPOSE

To evaluate distal femoral cartilage by shear wave elastography in patients with symptomatic knee osteoarthritis.

MATERIAL AND METHODS

Twenty patients with bilateral knee osteoarthritis (study group) and 20 volunteers with the same demographic characteristics but without symptomatic knee pain (control group) were included in the study. A total of 80 knee joints of 40 individuals were evaluated. At the medial, intercondylar, and lateral condylar levels distal femoral cartilage thickness was measured by B-mode ultrasonography and stiffness was measured by shear wave elastography.

RESULTS

The medial, intercondylar, and lateral cartilage thickness measurements were similar between the two groups and no statistically significant difference was observed (P = 0.711, P = 0.766, and P = 0.575, respectively). The shear wave velocity values in the medial and intercondylar cartilage were significantly higher in the study group (P = 0.002). Shear wave velocity values measured from lateral cartilage were higher in the study group and the difference between the groups had a borderline statistical significance (P = 0.053).

CONCLUSION

Shear wave elastography seems to be a reliable, non-invasive, and acceptable method for the assessment of pathologic cartilage.

Systematic review and meta-analysis of the reliability and discriminative validity of cartilage compositional MRI in knee osteoarthritis

OBJECTIVE

To assess reliability and discriminative validity of cartilage compositional magnetic resonance imaging (MRI) in knee osteoarthritis (OA).

DESIGN

The study was carried out per PRISMA recommendations. We searched MEDLINE and EMBASE (1974 - present) for eligible studies. We performed qualitative synthesis of reliability data. Where data from at least two discrimination studies were available, we estimated pooled standardized mean difference (SMD) between subjects with and without OA. Discrimination analyses compared controls and subjects with mild OA (Kellgren-Lawrence (KL) grade 1-2), severe OA (KL grade 3-4) and OA not otherwise specified (NOS) where not possible to stratify. We assessed quality of the evidence using Quality Appraisal of Diagnostic Reliability (QAREL) and Quality Assessment of Diagnostic Accuracy (QUADAS-2) tools.

RESULTS

Fifty-eight studies were included in the reliability analysis and 26 studies were included in the discrimination analysis, with data from a total of 2,007 knees. Intra-observer, inter-observer and test-retest reliability of compositional techniques were excellent with most intraclass correlation coefficients >0.8 and coefficients of variation <10%. T1rho and T2 relaxometry were significant discriminators between subjects with mild OA and controls, and between subjects with OA (NOS) and controls (P < 0.001). T1rho showed best discrimination for mild OA (SMD [95% CI] = 0.73 [0.40 to 1.06], P < 0.001) and OA (NOS) (0.60 [0.41 to 0.80], P < 0.001). Quality of evidence was moderate for both parts of the review.

CONCLUSIONS

Cartilage compositional MRI techniques are reliable and, in the case of T1rho and T2 relaxometry, can discriminate between subjects with OA and controls.

Morphologic and quantitative magnetic resonance imaging of knee articular cartilage for the assessment of post-traumatic osteoarthritis

Orthopedic trauma, such as anterior cruciate ligament (ACL) disruption, is a common source of osteoarthritis in the knee. Magnetic resonance imaging (MRI) is a non-invasive multi-planar imaging modality commonly used to evaluate hard and soft tissues of diarthrodial joints following traumatic injury. The contrast provided by generated images enables the evaluation of bone marrow lesions as well as delamination and degeneration of articular cartilage. We will provide background information about MRI signal generation and decay (T₁ and T₂ values), the utility of morphologic MRI, and the quantitative MRI techniques of T_1ρ , T₂ , and T₂ * mapping, to evaluate subjects with traumatic knee injuries, such as ACL rupture. Additionally, we will provide information regarding the dGEMRIC, sodium, and gagCEST imaging techniques. Finally, the description and utility of newer post hoc analysis techniques, such as texture analysis, will be given. Continued development and refinement of these advanced MRI techniques will facilitate their clinical translation. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:412-423, 2017.

Sex differences in sodium deposition in human muscle and skin

The aim of this work was to investigate possible sex differences in the patterns of sodium deposition between muscle and skin using sodium MRI. A total of 38 subjects were examined for comparisons: 20 males, aged 25-79years with a median age of 51; 18 females, aged 38-66years, median age 53. All subjects underwent sodium MRI scans of the calf muscles together with cross sections through four calibration standards containing known sodium contents (10mM, 20mM, 30mM, and 40mM). Tissue sodium concentrations (TSC) in muscle and skin were then calculated by comparing signal intensities between tissues and reference standards using a linear analysis. A Wilcoxon rank sum test was applied to the ΔTSC (=TSCmuscle-TSCskin) series of males and females to examine if they were significantly different. Finally, a multiple linear regression was utilized to account for the effects from two potential confounders, age and body mass index (BMI). We found that sodium content appears to be higher in skin than in muscle for men, however women tend to have higher muscle sodium than skin sodium. This sex-relevant sodium deposition is statistically significant (P=3.10×10-5) by the Wilcoxon rank sum test, and this difference in distribution seems to be more reliable with increasing age. In the multiple linear regression, gender still has a statistically significant effect (P<1.0×10-4) on the difference between sodium deposition in muscle and skin, while taking the effects of age and BMI into account.

Changes in Cartilage and Tendon Composition of Patients With Type I Diabetes Mellitus: Identification by Quantitative Sodium Magnetic Resonance Imaging at 7 T

OBJECTIVE

The aim of this study was to investigate possible biochemical alterations in tendons and cartilage caused by type 1 diabetes mellitus (DM1), using quantitative in vivo 7 T sodium magnetic resonance (MR) imaging.

MATERIALS AND METHODS

The institutional review board approved this prospective study, and written informed consent was obtained. Eight DM1 patients with no history of knee trauma and 9 healthy age- and weight-matched volunteers were examined at 7 T using dedicated knee coils.All participants underwent morphological and sodium MR imaging. Region-of-interest analysis was performed manually for the non-weight-bearing area of the femoral condyle cartilage and for the patella tendon. Two readers read the image data sets independently, twice, for intrareader and interreader agreement. Normalized mean sodium signal intensity (NMSI) values were compared between patients and volunteers for each reader using analysis of variance.

RESULTS

On morphological images, cartilage in the non-weight-bearing area and the patellar tendon was intact in all patients. On sodium MR imaging, bivariate analysis of variance showed significantly lower mean NMSI values in the cartilage (P = 0.008) and significantly higher values in the tendons (P = 0.025) of patients compared with those of volunteers.

CONCLUSION

Our study showed significantly different NMSI values between DM1 patients and matched volunteers. Differences observed in the cartilage and tendon might be associated with a DM1-related alteration of biochemical composition that occurs before it can be visualized on morphological MR sequences.

Quantitative sodium magnetic resonance imaging of cartilage, muscle, and tendon

Sodium magnetic resonance imaging (MRI), or imaging of the 23Na nucleus, has been under exploration for several decades, and holds promise for potentially revealing additional biochemical information about the health of tissues that cannot currently be obtained from conventional hydrogen (or proton) MRI. This additional information could serve as an important complement to conventional MRI for many applications. However, despite these exciting possibilities, sodium MRI is not yet used routinely in clinical practice, and will likely remain strictly in the domain of exploratory research for the coming decade. This paper begins with a technical overview of sodium MRI, including the nuclear magnetic resonance (NMR) signal characteristics of the sodium nucleus, the challenges associated with sodium MRI, and the specialized pulse sequences, hardware, and reconstruction techniques required. Various applications of sodium MRI for quantitative analysis of the musculoskeletal system are then reviewed, including the non-invasive assessment of cartilage degeneration in vivo, imaging of tendinopathy, applications in the assessment of various muscular pathologies, and assessment of muscle response to exercise.

MR Parametric Mapping as a Biomarker of Early Joint Degeneration

Context:

Osteoarthritis (OA) is a common, worldwide disorder. Magnetic resonance (MR) imaging can directly and noninvasively evaluate articular cartilage and has emerged as an essential tool in the study of OA.

Evidence Acquisition:

A PubMed search was performed using the keywords quantitative MRI and cartilage. No limits were set on the range of years searched. Articles were reviewed for relevance with an emphasis on in vivo studies performed at 3 tesla.

Study Design:

Clinical review.

Level of Evidence:

Level 4.

Results:

T2, T2*, T1 (particularly when measured after exogenous contrast administration, such as with the delayed gadolinium-enhanced MR imaging of cartilage [dGEMRIC] technique), and T1ρ are among the most widely utilized quantitative MR imaging techniques to evaluate cartilage and have been implemented in various patient cohorts. Existing challenges include reproducibility of results, insufficient consensus regarding optimal sequences and parameters, and interpretation of values.

Conclusion:

Quantitative assessment of cartilage using MR imaging techniques likely represents the best opportunity to identify early cartilage degeneration and to follow patients after treatment. Despite existing challenges, ongoing work and unique approaches have shown exciting and promising results.

Evaluation of cartilage repair and osteoarthritis with sodium MRI

The growing need for early diagnosis and higher specificity than that which can be achieved with morphological MRI is a driving force in the application of methods capable of probing the biochemical composition of cartilage tissue, such as sodium imaging. Unlike morphological imaging, sodium MRI is sensitive to even small changes in cartilage glycosaminoglycan content, which plays a key role in cartilage homeostasis. Recent advances in high- and ultrahigh-field MR systems, gradient technology, phase-array radiofrequency coils, parallel imaging approaches, MRI acquisition strategies and post-processing developments have resulted in many clinical in vivo sodium MRI studies of cartilage, even at 3 T. Sodium MRI has great promise as a non-invasive tool for cartilage evaluation. However, further hardware and software improvements are necessary to complete the translation of sodium MRI into a clinically feasible method for 3-T systems. This review is divided into three parts: (i) cartilage composition, pathology and treatment; (ii) sodium MRI; and (iii) clinical sodium MRI studies of cartilage with a focus on the evaluation of cartilage repair tissue and osteoarthritis.

Comparison of multiple quantitative MRI parameters for characterization of the goat cartilage in an ongoing osteoarthritis: dGEMRIC, T1ρ and sodium

RATIONALE AND OBJECTIVES

Osteoarthritis (OA) is a degenerative joint disease leading to cartilage deterioration by loss of matrix, fibrillation, formation of fissures, and ultimately complete loss of the cartilage surface. Here, three magnetic resonance imaging (MRI) techniques, dGEMRIC (delayed Gadolinium enhanced MRI of cartilage; dG1=T1,post; dG2=1/T1,post-1/T1,pre), T1ρ,and sodium MRI, are compared in a preclinical in vivo study to evaluate the differences in their potential for cartilage characterization and to establish an examination protocol for a following clinical study.

MATERIALS AND METHODS

OA was induced in 12 caprine knees (6 control, 6 therapy). Adipose derived stem cells were injected afterwards as a treatment. The animals were examined healthy, 3 and 16 weeks postoperatively with all three MRI methods. Using statistical analysis, the OA development and the degree of correlation between the different MRI methods were determined.

RESULTS

A strong correlation was observed between the dGEMRIC indices dG1 and dG2 (r=-0.87) which differ only in considering or not considering the T1 baseline. Moderate correlations were found between T1ρ and dG1 (r=0.55), T1ρ and dG2 (r=0.47) and at last, sodium and dG1 (r=0.45). The correlations found in this study match to the biomarkers which the methods are sensitive to.

CONCLUSION

Even though the goat cartilage is significantly thinner than the human cartilage and even more in a degenerated cartilage, all three methods were able to characterize the cartilage over the whole period of time during an ongoing OA. Due to measurement and post processing optimizations, as well as the correlations detected in this work, the overall measurement time in future goat studies can be minimized. Moreover, an examination protocol for characterizing the cartilage in a clinical study was established.

Magnetic resonance compositional imaging of articular cartilage: What can we expect in veterinary medicine?

Since cartilage has limited ability to repair itself, it is useful to determine its biochemical composition early in clinical cases. It is also important to assess cartilage content in research animals in longitudinal studies in vivo. In recent years, compositional imaging techniques using magnetic resonance imaging (MRI) have been developed to assess the biochemical composition of cartilage. This article describes MR compositional imaging techniques, and discusses their use and interpretation. Technical concerns still limit the use of some techniques for research and clinical use, especially in veterinary medicine. Glycosaminoglycan chemical-exchange saturation transfer and sodium imaging are better used with high field magnets, which have limited availability. Long acquisition times are sometimes required, for instance in T1rho (ρ) and diffusion-weighted imaging, and necessitate general anaesthesia. Even in human medicine, some techniques such as ultra-short echo T2 are not fully validated, and nearly all techniques require validation for veterinary research and clinical practice. Delayed gadolinium-enhanced MRI of cartilage and T2 mapping appear to be the most applicable methods for compositional imaging of animal cartilage. Combining T2 mapping and T1ρ allows for the assessment of proteoglycans and the collagen network, respectively.

Osteoarthritis year in review 2014: imaging

PURPOSE

This narrative review covers original publications related to imaging in osteoarthritis (OA) published in English between April 2013 and March 2014. In vitro data, animal studies and studies with less than 20 observations were not included.

METHODS

To extract relevant studies, an extensive PubMed database search was performed based on, but not limited to the query terms "Osteoarthritis" in combination with "MRI", "Imaging", "Radiography", "Ultrasound", "Computed Tomography" and "Nuclear Medicine". Publications were sorted according to relevance based on potential impact to the OA research community with the overarching goal of a balanced overview covering all aspects of imaging. Focus was on publications in high impact special interest journals. The literature will be presented in a methodological fashion covering radiography, ultrasound, compositional and morphologic Magnetic resonance imaging (MRI), and from an anatomic perspective including bone, muscle, meniscus and synovitis.

RESULTS AND CONCLUSIONS

Imaging research in OA in the last year was characterized by a strong focus on MRI-based studies dealing with epidemiological and methodological aspects of the disease. Ultrastructural tissue assessment specifically of cartilage and meniscus using compositional MRI is evolving further. Additional subsets of the large publicly available Osteoarthritis Initiative (OAI) MRI dataset are being analyzed at present and have been published with muscle analyses coming increasingly into the focus of the community. Bone parameters were evaluated using varying technology and a persistent interest in inflammatory disease manifestations has been noted. Other modalities than MRI have been less explored. To date most OA imaging research is still focused on the knee joint.

Quantitative magnetic resonance imaging of the articular cartilage of the knee joint

Osteoarthritis is characterized by a decrease in the proteoglycan content and disruption of the highly organized collagen fiber network of articular cartilage. Various quantitative magnetic resonance imaging techniques have been developed for noninvasive assessment of the proteoglycan and collagen components of cartilage. These techniques have been extensively used in clinical practice to detect early cartilage degeneration and in osteoarthritis research studies to monitor disease-related and treatment-related changes in cartilage over time. This article reviews the role of quantitative magnetic resonance imaging in evaluating the composition and ultrastructure of the articular cartilage of the knee joint.

Imaging of cartilage and bone: promises and pitfalls in clinical trials of osteoarthritis

Imaging in clinical trials is used to evaluate subject eligibility, and/or efficacy of intervention, supporting decision making in drug development by ascertaining treatment effects on joint structure. This review focusses on imaging of bone and cartilage in clinical trials of (knee) osteoarthritis. We narratively review the full-text literature on imaging of bone and cartilage, adding primary experience in the implementation of imaging methods in clinical trials. Aims and constraints of applying imaging in clinical trials are outlined. The specific uses of semi-quantitative and quantitative imaging biomarkers of bone and cartilage in osteoarthritis trials are summarized, focusing on radiography and magnetic resonance imaging (MRI). Studies having compared both imaging methodologies directly and those having established a relationship between imaging biomarkers and clinical outcomes are highlighted. To make this review of practical use, recommendations are provided as to which imaging protocols are ideal for capturing specific aspects of bone and cartilage tissue, and pitfalls in their usage are highlighted. Further, the longitudinal sensitivity to change, of different imaging methods is reported for various patient strata. From these power calculations can be accomplished, provided the strength of the treatment effect is known. In conclusion, current imaging methodologies provide powerful tools for scoring and measuring morphological and compositional aspects of most articular tissues, capturing longitudinal change with reasonable to excellent sensitivity. When employed properly, imaging has tremendous potential for ascertaining treatment effects on various joint structures, potentially over shorter time scales than required for demonstrating effects on clinical outcomes.