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Tuppurainen J, Paakkari P, Jäntti J, Nissinen MT, Fugazzola MC, van Weeren R, Ylisiurua S, Nieminen MT, Kröger H, Snyder BD, Joenathan A, Grinstaff MW, Matikka H, Korhonen RK, Mäkelä JTA. Revealing Detailed Cartilage Function Through Nanoparticle Diffusion Imaging: A Computed Tomography & Finite Element Study. Ann Biomed Eng 2024:10.1007/s10439-024-03552-7. [PMID: 39012563 DOI: 10.1007/s10439-024-03552-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Accepted: 05/23/2024] [Indexed: 07/17/2024]
Abstract
The ability of articular cartilage to withstand significant mechanical stresses during activities, such as walking or running, relies on its distinctive structure. Integrating detailed tissue properties into subject-specific biomechanical models is challenging due to the complexity of analyzing these characteristics. This limitation compromises the accuracy of models in replicating cartilage function and impacts predictive capabilities. To address this, methods revealing cartilage function at the constituent-specific level are essential. In this study, we demonstrated that computational modeling derived individual constituent-specific biomechanical properties could be predicted by a novel nanoparticle contrast-enhanced computer tomography (CECT) method. We imaged articular cartilage samples collected from the equine stifle joint (n = 60) using contrast-enhanced micro-computed tomography (µCECT) to determine contrast agents' intake within the samples, and compared those to cartilage functional properties, derived from a fibril-reinforced poroelastic finite element model. Two distinct imaging techniques were investigated: conventional energy-integrating µCECT employing a cationic tantalum oxide nanoparticle (Ta2O5-cNP) contrast agent and novel photon-counting µCECT utilizing a dual-contrast agent, comprising Ta2O5-cNP and neutral iodixanol. The results demonstrate the capacity to evaluate fibrillar and non-fibrillar functionality of cartilage, along with permeability-affected fluid flow in cartilage. This finding indicates the feasibility of incorporating these specific functional properties into biomechanical computational models, holding potential for personalized approaches to cartilage diagnostics and treatment.
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Affiliation(s)
- Juuso Tuppurainen
- Department of Technical Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland.
- Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland.
| | - Petri Paakkari
- Department of Technical Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland
- Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland
| | - Jiri Jäntti
- Department of Technical Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland
- Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland
| | - Mikko T Nissinen
- Department of Technical Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland
| | - Maria C Fugazzola
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - René van Weeren
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Sampo Ylisiurua
- Research Unit of Health Sciences and Technology, University of Oulu, Oulu, Finland
- Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland
| | - Miika T Nieminen
- Research Unit of Health Sciences and Technology, University of Oulu, Oulu, Finland
- Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland
| | - Heikki Kröger
- Department of Orthopaedics and Traumatology, Kuopio University Hospital, Kuopio, Finland
- Kuopio Musculoskeletal Research Unit, University of Eastern Finland, Kuopio, Finland
| | - Brian D Snyder
- Department of Orthopedic Surgery, Boston Children's Hospital, Boston, USA
| | - Anisha Joenathan
- Departments of Biomedical Engineering and Chemistry, Boston University, Boston, USA
| | - Mark W Grinstaff
- Departments of Biomedical Engineering and Chemistry, Boston University, Boston, USA
| | - Hanna Matikka
- Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland
| | - Rami K Korhonen
- Department of Technical Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland
| | - Janne T A Mäkelä
- Department of Technical Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland
- Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland
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2
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Kafian-Attari I, Nippolainen E, Bergmann F, Mirhashemi A, Paakkari P, Foschum F, Kienle A, Töyräs J, Afara IO. Impact of experimental setup parameters on the measurement of articular cartilage optical properties in the visible and short near-infrared spectral bands. BIOMEDICAL OPTICS EXPRESS 2023; 14:3397-3412. [PMID: 37497494 PMCID: PMC10368039 DOI: 10.1364/boe.488801] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 05/08/2023] [Accepted: 05/13/2023] [Indexed: 07/28/2023]
Abstract
There is increasing research on the potential application of diffuse optical spectroscopy and hyperspectral imaging for characterizing the health of the connective tissues, such as articular cartilage, during joint surgery. These optical techniques facilitate the rapid and objective diagnostic assessment of the tissue, thus providing unprecedented information toward optimal treatment strategy. Adaption of optical techniques for diagnostic assessment of musculoskeletal disorders, including osteoarthritis, requires precise determination of the optical properties of connective tissues such as articular cartilage. As every indirect method of tissue optical properties estimation consists of a measurement step followed by a computational analysis step, there are parameters associated with these steps that could influence the estimated values of the optical properties. In this study, we report the absorption and reduced scattering coefficients of articular cartilage in the spectral band of 400-1400 nm. We assess the impact of the experimental setup parameters, including surrounding medium, sample volume, and scattering anisotropy factor on the reported optical properties. Our results suggest that the absorption coefficient of articular cartilage is sensitive to the variation in the surrounding medium, whereas its reduced scattering coefficient is invariant to the experimental setup parameters.
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Affiliation(s)
- Iman Kafian-Attari
- Department of Technical Physics, University of Eastern Finland, Finland
- Diagnostic Imaging Center, Kuopio University Hospital, Finland
| | - Ervin Nippolainen
- Department of Technical Physics, University of Eastern Finland, Finland
| | - Florian Bergmann
- Institute for Laser Technologies in Medicine and Meteorology, University of Ulm, Germany
| | - Arash Mirhashemi
- Department of Technical Physics, University of Eastern Finland, Finland
| | - Petri Paakkari
- Department of Technical Physics, University of Eastern Finland, Finland
- Diagnostic Imaging Center, Kuopio University Hospital, Finland
| | - Florian Foschum
- Institute for Laser Technologies in Medicine and Meteorology, University of Ulm, Germany
| | - Alwin Kienle
- Institute for Laser Technologies in Medicine and Meteorology, University of Ulm, Germany
| | - Juha Töyräs
- Department of Technical Physics, University of Eastern Finland, Finland
- Science Service Center, Kuopio University Hospital, Finland
- School of Information Technology and Electrical Engineering, University of Queensland, Australia
| | - Isaac O. Afara
- Department of Technical Physics, University of Eastern Finland, Finland
- School of Information Technology and Electrical Engineering, University of Queensland, Australia
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3
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Sasaki S, Sasaki E, Yamamoto Y, Kimura Y, Chiba D, Tsushima T, Tsuda E, Ishibashi Y. Spectroscopic Quantitative Measurement of the Cartilage Surface using Arthroscopy Correlates with a Conventional Macroscopic Grading System. Arthrosc Sports Med Rehabil 2022; 5:e233-e238. [PMID: 36866322 PMCID: PMC9971858 DOI: 10.1016/j.asmr.2022.11.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 11/13/2022] [Indexed: 12/29/2022] Open
Abstract
Purpose To quantify the cartilage surface profile visualized during arthroscopic surgery and examine its clinical utility by comparing the results of quantitative measurements with a conventional grading system. Methods Fifty consecutive patients diagnosed with knee osteoarthritis and who underwent arthroscopic surgery were included in this study. A 4 K camera system was used, and the cartilage surface profile was visualized using the augmented reality imaging program. The highlighted image was displayed in 2 colors: black (the worn cartilage area) and green (the part where the cartilage thickness was maintained). The percentage of the green area was calculated using ImageJ and used as an index of cartilage degeneration. The quantitative value was statistically compared with the International Cartilage Repair Society (ICRS) grade as a conventional macroscopic evaluation. Results In the quantitative measurement, the median percentage of the green area was 60.7 at ICRS grades 0 and 1 (interquartile range [IQR], 67.3-51.0), 47.2 at grade 2 (IQR, 54.1-39.2), 36.5 at grade 3 (IQR, 43.2-30.4), and 34.0 at grade 4 (IQR, 38.5-29.3). There was a significant difference between the macroscopic grades, except for Grades 3 and 4. There was a significant negative correlation between macroscopic evaluation and quantitative measurement (r = -0.672, P < .001). Conclusions The quantitative measurement of the cartilage surface profile using the spectroscopic absorption technique was significantly correlated with the conventional macroscopic grading system and demonstrated fair to good inter-rater and intra-rater reliabilities. Level of Evidence Level II, diagnostic (prospective cohort study).
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Affiliation(s)
- Shizuka Sasaki
- Address correspondence to Shizuka Sasaki, M.D., Department of Orthopaedic Surgery, Aomori City Hospital, Katta 1-14-20, Aomori, Aomori 030-0821, Japan
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Hall ME, Wang AS, Gold GE, Levenston ME. Contrast solution properties and scan parameters influence the apparent diffusivity of computed tomography contrast agents in articular cartilage. JOURNAL OF THE ROYAL SOCIETY, INTERFACE 2022; 19:20220403. [PMID: 35919981 PMCID: PMC9346352 DOI: 10.1098/rsif.2022.0403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The inability to detect early degenerative changes to the articular cartilage surface that commonly precede bulk osteoarthritic degradation is an obstacle to early disease detection for research or clinical diagnosis. Leveraging a known artefact that blurs tissue boundaries in clinical arthrograms, contrast agent (CA) diffusivity can be derived from computed tomography arthrography (CTa) scans. We combined experimental and computational approaches to study protocol variations that may alter the CTa-derived apparent diffusivity. In experimental studies on bovine cartilage explants, we examined how CA dilution and transport direction (absorption versus desorption) influence the apparent diffusivity of untreated and enzymatically digested cartilage. Using multiphysics simulations, we examined mechanisms underlying experimental observations and the effects of image resolution, scan interval and early scan termination. The apparent diffusivity during absorption decreased with increasing CA concentration by an amount similar to the increase induced by tissue digestion. Models indicated that osmotically-induced fluid efflux strongly contributed to the concentration effect. Simulated changes to spatial resolution, scan spacing and total scan time all influenced the apparent diffusivity, indicating the importance of consistent protocols. With careful control of imaging protocols and interpretations guided by transport models, CTa-derived diffusivity offers promise as a biomarker for early degenerative changes.
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Affiliation(s)
- Mary E Hall
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Adam S Wang
- Department of Radiology, Stanford University, Stanford, CA, USA.,Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Garry E Gold
- Department of Radiology, Stanford University, Stanford, CA, USA.,Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Marc E Levenston
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA.,Department of Radiology, Stanford University, Stanford, CA, USA
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5
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Kazemi M, Williams JL. Properties of Cartilage-Subchondral Bone Junctions: A Narrative Review with Specific Focus on the Growth Plate. Cartilage 2021; 13:16S-33S. [PMID: 32458695 PMCID: PMC8804776 DOI: 10.1177/1947603520924776] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVE The purpose of this narrative review is to summarize what is currently known about the structural, chemical, and mechanical properties of cartilage-bone interfaces, which provide tissue integrity across a bimaterial interface of 2 very different structural materials. Maintaining these mechanical interfaces is a key factor for normal bone growth and articular cartilage function and maintenance. MATERIALS AND METHODS A comprehensive search was conducted using Google Scholar and PubMed/Medline with a specific focus on the growth plate cartilage-subchondral bone interface. All original articles, reviews in journals, and book chapters were considered. Following a review of the overall structural and functional characteristics of the physis, the literature on histological studies of both articular and growth plate chondro-osseous junctions is briefly reviewed. Next the literature on biochemical properties of these interfaces is reviewed, specifically the literature on elemental analyses across the cartilage-subchondral bone junctions. The literature on biomechanical studies of these junctions at the articular and physeal interfaces is also reviewed and compared. RESULTS Unlike the interface between articular cartilage and bone, growth plate cartilage has 2 chondro-osseous junctions. The reserve zone of the mature growth plate is intimately connected to a plate of subchondral bone on the epiphyseal side. This interface resembles that between the subchondral bone and articular cartilage, although much less is known about its makeup and formation. CONCLUSION There is a notably paucity of information available on the structural and mechanical properties of reserve zone-subchondral epiphyseal bone interface. This review reveals that further studies are needed on the microstructural and mechanical properties of chondro-osseous junction with the reserve zone.
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Affiliation(s)
- Masumeh Kazemi
- Biomedical Engineering Department,
University of Memphis, Memphis, TN, USA,Masumeh Kazemi, Biomedical Engineering
Department, University of Memphis, 3796 Norriswood Avenue, Memphis, TN 38152,
USA.
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6
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Flynn C, Hurtig M, zur Linden A. Anionic Contrast-Enhanced MicroCT Imaging Correlates with Biochemical and Histological Evaluations of Osteoarthritic Articular Cartilage. Cartilage 2021; 13:1388S-1397S. [PMID: 32456450 PMCID: PMC8804789 DOI: 10.1177/1947603520924748] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
This study addressed difficulties in evaluating osteoarthritis (OA) progression in species with thin cartilage. Feasibility of using short, nonequilibrium contrast-enhanced micro-computed tomography (CE-μCT) to evaluate the physical and biochemical properties of cartilage was investigated. A preliminary in vitro study using CE-μCT study was performed using bovine osteochondral blocks with intact, mildly damaged (fibrillated), or severely damaged (delaminated) cartilage. Delamination of the superficial zone resulted in elevated apparent density compared with intact cartilage after 10 minutes of anionic contrast exposure (P < 0.01). OA was induced by unilateral meniscal destabilization in n = 20 sheep divided into: early phase OA (n = 9) and late phase OA (n = 11), while n = 4 remained as naive controls. In vivo anionic nonequilibrium contrast CT of the operated stifle was conducted in the early phase sheep 13 weeks postoperatively using clinical resolution CT. Cartilage visibility in the contrasted leg was significantly improved compared with the noncontrasted contralateral stifle (P < 0.05). Animals were sacrificed at 3 months (early phase) or 12 months (late phase) for additional ex vivo CE-μCT, and correlative tests with biochemical and histological measures. Concentration of sulfated glycosaminoglycan (sGAG) significantly varied between control, early, and late phase OA (P < 0.005) and showed a negative (r = -0.56) relationship with apparent density in the medial tibial plateau (R2 = 0.28, P < 0.001). Histologically, parameters in proteoglycan and cartilage surface structure correlated with increasing attenuation. While previous studies have shown that CE-CT increases the apparent density of proteoglycan-depleted cartilage, we concluded that superficial zone disruption also contributes to this phenomenon.
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Affiliation(s)
- Candace Flynn
- Department of Clinical Studies, Ontario
Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Mark Hurtig
- Department of Clinical Studies, Ontario
Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Alex zur Linden
- Department of Clinical Studies, Ontario
Veterinary College, University of Guelph, Guelph, Ontario, Canada
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7
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Travascio F, Valladares-Prieto S, Jackson AR. EFFECTS OF SOLUTE SIZE AND TISSUE COMPOSITION ON MOLECULAR AND MACROMOLECULAR DIFFUSIVITY IN HUMAN KNEE CARTILAGE. OSTEOARTHRITIS AND CARTILAGE OPEN 2021; 2. [PMID: 34611626 DOI: 10.1016/j.ocarto.2020.100087] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Objective Articular cartilage is an avascular tissue. Accordingly, diffusivity represents a fundamental transport mechanism for nutrients and other molecular signals regulating its cell metabolism and maintenance of the extracellular matrix. Understanding how solutes spread into articular cartilage is crucial to elucidating its pathologies, and to designing treatments for repair and restoration of its extracellular matrix. As in other connective tissues, diffusivity in articular cartilage may vary depending both its composition and the specific diffusing solute. Hence, this study investigated the roles of solute size and tissue composition on molecular diffusion in knee articular cartilage. Design FRAP tests were conducted to measure diffusivity of five molecular probes, with size ranging from ~332Da to 70,000Da, in human knee articular cartilage. The measured diffusion coefficients were related to molecular size, as well as water and glycosaminoglycan (GAG) content of femoral and tibial condyle cartilage. Results Diffusivity was affected by molecular size, with the magnitude of the diffusion coefficients decreasing as the Stokes radius of the probe increased. The values of diffusion coefficients in tibial and femoral samples were not significantly different from one another, despite the fact that tibial samples exhibited significantly higher water content and lower GAG content of the femoral specimens. Water content did not affect diffusivity. In contrast, diffusivities of large molecules were sensitive to GAG content. Conclusions This study provides new knowledge on the mechanisms of diffusion in articular cartilage. Our findings can be leveraged to further investigate osteoarthritis and to design treatments for cartilage restoration or replacement.
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Affiliation(s)
- Francesco Travascio
- Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL.,Department of Orthopaedic Surgery, University of Miami, Miami, FL.,Max Biedermann Institute for Biomechanics at Mount Sinai Medical Center, Miami Beach, FL
| | | | - Alicia R Jackson
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL
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Simultaneous Quantitation of Cationic and Non-ionic Contrast Agents in Articular Cartilage Using Synchrotron MicroCT Imaging. Sci Rep 2019; 9:7118. [PMID: 31068614 PMCID: PMC6506503 DOI: 10.1038/s41598-019-43276-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 04/15/2019] [Indexed: 01/15/2023] Open
Abstract
Early diagnosis of acute cartilage injuries enables monitoring of disease progression and improved treatment option planning to prevent post-traumatic osteoarthritis. In contrast-enhanced computed tomography (CECT), the changes in cationic agent diffusion within the tissue reflect cartilage degeneration. The diffusion in degenerated cartilage depends on proteoglycan (PG) content and water content, but each having an opposite effect on diffusion, thus compromising the diagnostic sensitivity. To overcome this limitation, we propose the simultaneous imaging of cationic (sensitive to PG and water contents) and non-ionic (sensitive to water content) agents. In this study, quantitative dual-energy CT (QDECT) imaging of two agents is reported for the first time at clinically feasible imaging time points. Furthermore, this is the first time synchrotron microCT with monochromatic X-rays is employed in cartilage CECT. Imaging was conducted at 1 and 2 h post contrast agent immersion. Intact, PG-depleted, and mechanically injured + PG-depleted cartilage samples (n = 33) were imaged in a mixture of cationic (iodine-based CA4+) and non-ionic (gadolinium-based gadoteridol) agents. Concurrent evaluation of CA4+ and gadoteridol partitions in cartilage is accomplished using QDECT. Subsequent normalization of the CA4+ partition with that of the gadoteridol affords CA4+ attenuations that significantly correlate with PG content – a key marker of OA.
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9
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Honkanen MKM, Matikka H, Honkanen JTJ, Bhattarai A, Grinstaff MW, Joukainen A, Kröger H, Jurvelin JS, Töyräs J. Imaging of proteoglycan and water contents in human articular cartilage with full-body CT using dual contrast technique. J Orthop Res 2019; 37:1059-1070. [PMID: 30816584 PMCID: PMC6594070 DOI: 10.1002/jor.24256] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 02/12/2019] [Indexed: 02/04/2023]
Abstract
Assessment of cartilage composition via tomographic imaging is critical after cartilage injury to prevent post-traumatic osteoarthritis. Diffusion of cationic contrast agents in cartilage is affected by proteoglycan loss and elevated water content. These changes have opposite effects on diffusion and, thereby, reduce the diagnostic accuracy of cationic agents. Here, we apply, for the first time, a clinical full-body CT for dual contrast imaging of articular cartilage. We hypothesize that full-body CT can simultaneously determine the diffusion and partitioning of cationic and non-ionic contrast agents and that normalization of the cationic agent partition with that of the non-ionic agent minimizes the effect of water content and tissue permeability, especially at early diffusion time points. Cylindrical (d = 8 mm) human osteochondral samples (n = 45; four cadavers) of a variable degenerative state were immersed in a mixture of cationic iodinated CA4+ and non-charged gadoteridol contrast agents and imaged with a full-body CT scanner at various time points. Determination of contrast agents' distributions within cartilage was possible at all phases of diffusion. At early time points, gadoteridol, and CA4+ distributed throughout cartilage with lower concentrations in the deep cartilage. At ≥24 h, the gadoteridol concentration remained nearly constant, while the CA4+ concentration increased toward deep cartilage. Normalization of the CA4+ partition with that of gadoteridol significantly (p < 0.05) enhanced correlation with proteoglycan content and Mankin score at the early time points. To conclude, the dual contrast technique was found advantageous over single contrast imaging enabling more sensitive diagnosis of cartilage degeneration. © 2019 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. J Orthop Res 9999:1-12, 2019.
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Affiliation(s)
- Miitu K. M. Honkanen
- Department of Applied PhysicsUniversity of Eastern FinlandKuopioFinland,Diagnostic Imaging CenterKuopio University HospitalKuopioFinland
| | - Hanna Matikka
- Department of Clinical RadiologyDiagnostic Imaging CenterKuopio University HospitalKuopioFinland
| | | | - Abhisek Bhattarai
- Department of Applied PhysicsUniversity of Eastern FinlandKuopioFinland,Diagnostic Imaging CenterKuopio University HospitalKuopioFinland
| | - Mark W. Grinstaff
- Departments of Biomedical Engineering, Chemistry, and MedicineBoston UniversityBostonMassachusetts
| | - Antti Joukainen
- Department of Orthopedics, Traumatology and Hand SurgeryKuopio University HospitalKuopioFinland
| | - Heikki Kröger
- Department of Orthopedics, Traumatology and Hand SurgeryKuopio University HospitalKuopioFinland
| | - Jukka S. Jurvelin
- Department of Applied PhysicsUniversity of Eastern FinlandKuopioFinland
| | - Juha Töyräs
- Department of Applied PhysicsUniversity of Eastern FinlandKuopioFinland,Diagnostic Imaging CenterKuopio University HospitalKuopioFinland,School of Information Technology and Electrical EngineeringThe University of QueenslandBrisbaneAustralia
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10
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Aging does not change the compressive stiffness of mandibular condylar cartilage in horses. Osteoarthritis Cartilage 2018; 26:1744-1752. [PMID: 30145230 DOI: 10.1016/j.joca.2018.08.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 08/13/2018] [Accepted: 08/13/2018] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Aging can cause an increase in the stiffness of hyaline cartilage as a consequence of increased protein crosslinks. By induction of crosslinking, a reduction in the diffusion of solutions into the hyaline cartilage has been observed. However, there is a lack of knowledge about the effects of aging on the biophysical and biochemical properties of the temporomandibular joint (TMJ) cartilage. Hence, the aim of this study was to examine the biophysical properties (thickness, stiffness, and diffusion) of the TMJ condylar cartilage of horses of different ages and their correlation with biochemical parameters. MATERIALS AND METHODS We measured the compressive stiffness of the condyles, after which the diffusion of two contrast agents into cartilage was measured using Contrast Enhanced Computed Tomography technique. Furthermore, the content of water, collagen, GAG, and pentosidine was analyzed. RESULTS Contrary to our expectations, the stiffness of the cartilage did not change with age (modulus remained around 0.7 MPa). The diffusion of the negatively charged contrast agent (Hexabrix) also did not alter. However, the diffusion of the uncharged contrast agent (Visipaque) decreased with aging. The flux was negatively correlated with the amount of collagen and crosslink level which increased with aging. Pentosidine, collagen, and GAG were positively correlated with age whereas thickness and water content showed negative correlations. CONCLUSION Our data demonstrated that aging was not necessarily reflected in the biophysical properties of TMJ condylar cartilage. The combination of the changes happening due to aging resulted in different diffusive properties, depending on the nature of the solution.
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11
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Diffusion of charged and uncharged contrast agents in equine mandibular condylar cartilage is not affected by an increased level of sugar-induced collagen crosslinking. J Mech Behav Biomed Mater 2018; 90:133-139. [PMID: 30366303 DOI: 10.1016/j.jmbbm.2018.10.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 09/27/2018] [Accepted: 10/12/2018] [Indexed: 11/20/2022]
Abstract
Nutrition of articular cartilage relies mainly on diffusion and convection of solutes through the interstitial fluid due to the lack of blood vessels. The diffusion is controlled by two factors: steric hindrance and electrostatic interactions between the solutes and the matrix components. Aging comes with changes in the cartilage structure and composition, which can influence the diffusion. In this study, we treated fibrocartilage of mandibular condyle with ribose to induce an aging-like effect by accumulating collagen crosslinks. The effect of steric hindrance or electrostatic forces on the diffusion was analyzed using either charged (Hexabrix) or uncharged (Visipaque) contrast agents. Osteochondral plugs from young equine mandibular condyles were treated with 500 mM ribose for 7 days. The effect of crosslinking on mechanical properties was then evaluated via dynamic indentation. Thereafter, the samples were exposed to contrast agents and imaged using contrast-enhanced computed tomography (CECT) at 18 different time points up to 48 h to measure their diffusion. Normalized concentration of contrast agents in the cartilage and contrast agent diffusion flux, as well as the content of crosslink level (pentosidine), water, collagen, and glycosaminoglycan (GAG) were determined. Ribose treatment significantly increased the pentosidine level (from 0.01 to 7.6 mmol/mol collagen), which resulted in an increase in tissue stiffness (~1.5 fold). Interestingly, the normalized concentration and diffusion flux did not change after the induction of an increased level of pentosidine either for Hexabrix or Visipaque. The results of this study strongly suggest that sugar-induced collagen crosslinking in TMJ condylar cartilage does not affect the diffusion properties.
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12
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Multi-scale imaging techniques to investigate solute transport across articular cartilage. J Biomech 2018; 78:10-20. [DOI: 10.1016/j.jbiomech.2018.06.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 06/11/2018] [Accepted: 06/19/2018] [Indexed: 12/31/2022]
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Method for Segmentation of Knee Articular Cartilages Based on Contrast-Enhanced CT Images. Ann Biomed Eng 2018; 46:1756-1767. [PMID: 30132213 DOI: 10.1007/s10439-018-2081-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 06/20/2018] [Indexed: 12/22/2022]
Abstract
Segmentation of contrast-enhanced computed tomography (CECT) images enables quantitative evaluation of morphology of articular cartilage as well as the significance of the lesions. Unfortunately, automatic segmentation methods for CECT images are currently lacking. Here, we introduce a semiautomated technique to segment articular cartilage from in vivo CECT images of human knee. The segmented cartilage geometries of nine knee joints, imaged using a clinical CT-scanner with an intra-articular contrast agent, were compared with manual segmentations from CT and magnetic resonance (MR) images. The Dice similarity coefficients (DSCs) between semiautomatic and manual CT segmentations were 0.79-0.83 and sensitivity and specificity values were also high (0.76-0.86). When comparing semiautomatic and manual CT segmentations, mean cartilage thicknesses agreed well (intraclass correlation coefficient = 0.85-0.93); the difference in thickness (mean ± SD) was 0.27 ± 0.03 mm. Differences in DSC, when MR segmentations were compared with manual and semiautomated CT segmentations, were statistically insignificant. Similarly, differences in volume were not statistically significant between manual and semiautomatic CT segmentations. Semiautomation decreased the segmentation time from 450 ± 190 to 42 ± 10 min per joint. The results reveal that the proposed technique is fast and reliable for segmentation of cartilage. Importantly, this is the first study presenting semiautomated segmentation of cartilage from CECT images of human knee joint with minimal user interaction.
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14
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Foster RJ, Damion RA, Ries ME, Smye SW, McGonagle DG, Binks DA, Radjenovic A. Imaging of nuclear magnetic resonance spin-lattice relaxation activation energy in cartilage. ROYAL SOCIETY OPEN SCIENCE 2018; 5:180221. [PMID: 30109078 PMCID: PMC6083713 DOI: 10.1098/rsos.180221] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 05/29/2018] [Indexed: 06/08/2023]
Abstract
Samples of human and bovine cartilage have been examined using magnetic resonance imaging to determine the proton nuclear magnetic resonance spin-lattice relaxation time, T1, as a function of depth within through the cartilage tissue. T1 was measured at five to seven temperatures between 8 and 38°C. From this, it is shown that the T1 relaxation time is well described by Arrhenius-type behaviour and the activation energy of the relaxation process is quantified. The activation energy within the cartilage is approximately 11 ± 2 kJ mol-1 with this notably being less than that for both pure water (16.6 ± 0.4 kJ mol-1) and the phosphate-buffered solution in which the cartilage was immersed (14.7 ± 1.0 kJ mol-1). It is shown that this activation energy increases as a function of depth in the cartilage. It is known that cartilage composition varies with depth, and hence, these results have been interpreted in terms of the structure within the cartilage tissue and the association of the water with the macromolecular constituents of the cartilage.
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Affiliation(s)
- R. J. Foster
- Soft Matter Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
- Leeds Musculoskeletal Biomedical Research Unit, Chapel Allerton Hospital, University of Leeds, Leeds LS4 7SA, UK
| | - R. A. Damion
- Soft Matter Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - M. E. Ries
- Soft Matter Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - S. W. Smye
- School of Medicine, University of Leeds, Leeds LS2 9JT, UK
- Leeds Musculoskeletal Biomedical Research Unit, Chapel Allerton Hospital, University of Leeds, Leeds LS4 7SA, UK
| | - D. G. McGonagle
- Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds LS2 9JT, UK
- Leeds Musculoskeletal Biomedical Research Unit, Chapel Allerton Hospital, University of Leeds, Leeds LS4 7SA, UK
| | - D. A. Binks
- Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds LS2 9JT, UK
- Leeds Musculoskeletal Biomedical Research Unit, Chapel Allerton Hospital, University of Leeds, Leeds LS4 7SA, UK
| | - A. Radjenovic
- Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds LS2 9JT, UK
- Leeds Musculoskeletal Biomedical Research Unit, Chapel Allerton Hospital, University of Leeds, Leeds LS4 7SA, UK
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15
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Pouran B, Moshtagh PR, Arbabi V, Snabel J, Stoop R, Ruberti J, Malda J, Zadpoor AA, Weinans H. Non-enzymatic cross-linking of collagen type II fibrils is tuned via osmolality switch. J Orthop Res 2018; 36:1929-1936. [PMID: 29334127 PMCID: PMC6099510 DOI: 10.1002/jor.23857] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 01/08/2018] [Indexed: 02/04/2023]
Abstract
An important aspect in cartilage ageing is accumulation of advanced glycation end products (AGEs) after exposure to sugars. Advanced glycation results in cross-links formation between the collagen fibrils in articular cartilage, hampering their flexibility and making cartilage more brittle. In the current study, we investigate whether collagen cross-linking after exposure to sugars depends on the stretching condition of the collagen fibrils. Healthy equine cartilage specimens were exposed to l-threose sugar and placed in hypo-, iso-, or hyper-osmolal conditions that expanded or shrank the tissue and changed the 3D conformation of collagen fibrils. We applied micro-indentation tests, contrast enhanced micro-computed tomography, biochemical measurement of pentosidine cross-links, and cartilage surface color analysis to assess the effects of advanced glycation cross-linking under these different conditions. Swelling of extracellular matrix due to hypo-osmolality made cartilage less susceptible to advanced glycation, namely, the increase in effective Young's modulus was approximately 80% lower in hypo-osmolality compared to hyper-osmolality and pentosidine content per collagen was 47% lower. These results indicate that healthy levels of glycosaminoglycans not only keep cartilage stiffness at appropriate levels by swelling and pre-stressed collagen fibrils, but also protect collagen fibrils from adverse effects of advanced glycation. These findings highlight the fact that collagen fibrils and therefore cartilage can be protected from further advanced glycation ("ageing") by maintaining the joint environment at sufficiently low osmolality. Understanding of mechanochemistry of collagen fibrils provided here might evoke potential ageing prohibiting strategies against cartilage deterioration. © 2018 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 36:1929-1936, 2018.
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Affiliation(s)
- Behdad Pouran
- Department of OrthopedicsUMC UtrechtHeidelberglaan100, 3584CX UtrechtThe Netherlands,Faculty of Mechanical, Maritime, and Materials Engineering, Department of Biomechanical EngineeringDelft University of Technology (TU Delft)Mekelweg 2, 2628CDDelftThe Netherlands
| | - Parisa R. Moshtagh
- Department of OrthopedicsUMC UtrechtHeidelberglaan100, 3584CX UtrechtThe Netherlands,Faculty of Mechanical, Maritime, and Materials Engineering, Department of Biomechanical EngineeringDelft University of Technology (TU Delft)Mekelweg 2, 2628CDDelftThe Netherlands
| | - Vahid Arbabi
- Department of OrthopedicsUMC UtrechtHeidelberglaan100, 3584CX UtrechtThe Netherlands,Faculty of Mechanical, Maritime, and Materials Engineering, Department of Biomechanical EngineeringDelft University of Technology (TU Delft)Mekelweg 2, 2628CDDelftThe Netherlands,Faculty of Engineering, Department of Mechanical EngineeringUniversity of Birjand615/97175BirjandIran
| | - Jessica Snabel
- Department of Metabolic Health ResearchTNOP.O. Box 22152301 CE LeidenThe Netherlands
| | - Reinout Stoop
- Department of Metabolic Health ResearchTNOP.O. Box 22152301 CE LeidenThe Netherlands
| | - Jeffrey Ruberti
- Department of BioengineeringNortheastern, University360 Huntington AvenueBostonMassachusetts02115
| | - Jos Malda
- Department of OrthopedicsUMC UtrechtHeidelberglaan100, 3584CX UtrechtThe Netherlands,Faculty of Veterinary Sciences, Department of Equine SciencesUtrecht UniversityYalelaan 1123584 CM UtrechtThe Netherlands
| | - Amir A. Zadpoor
- Faculty of Mechanical, Maritime, and Materials Engineering, Department of Biomechanical EngineeringDelft University of Technology (TU Delft)Mekelweg 2, 2628CDDelftThe Netherlands
| | - Harrie Weinans
- Department of OrthopedicsUMC UtrechtHeidelberglaan100, 3584CX UtrechtThe Netherlands,Faculty of Mechanical, Maritime, and Materials Engineering, Department of Biomechanical EngineeringDelft University of Technology (TU Delft)Mekelweg 2, 2628CDDelftThe Netherlands,Department of RheumatologyUMC UtrechtHeidelberglaan1003584CX UtrechtThe Netherlands
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16
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Effects of non-enzymatic glycation on the micro- and nano-mechanics of articular cartilage. J Mech Behav Biomed Mater 2018; 77:551-556. [DOI: 10.1016/j.jmbbm.2017.09.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 09/16/2017] [Accepted: 09/27/2017] [Indexed: 11/18/2022]
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17
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Saukko AEA, Honkanen JTJ, Xu W, Väänänen SP, Jurvelin JS, Lehto VP, Töyräs J. Dual Contrast CT Method Enables Diagnostics of Cartilage Injuries and Degeneration Using a Single CT Image. Ann Biomed Eng 2017; 45:2857-2866. [PMID: 28924827 DOI: 10.1007/s10439-017-1916-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 09/01/2017] [Indexed: 02/07/2023]
Abstract
Cartilage injuries may be detected using contrast-enhanced computed tomography (CECT) by observing variations in distribution of anionic contrast agent within cartilage. Currently, clinical CECT enables detection of injuries and related post-traumatic degeneration based on two subsequent CT scans. The first scan allows segmentation of articular surfaces and lesions while the latter scan allows evaluation of tissue properties. Segmentation of articular surfaces from the latter scan is difficult since the contrast agent diffusion diminishes the image contrast at surfaces. We hypothesize that this can be overcome by mixing anionic contrast agent (ioxaglate) with bismuth oxide nanoparticles (BINPs) too large to diffuse into cartilage, inducing a high contrast at the surfaces. Here, a dual contrast method employing this mixture is evaluated by determining the depth-wise X-ray attenuation profiles in intact, enzymatically degraded, and mechanically injured osteochondral samples (n = 3 × 10) using a microCT immediately and at 45 min after immersion in contrast agent. BiNPs were unable to diffuse into cartilage, producing high contrast at articular surfaces. Ioxaglate enabled the detection of enzymatic and mechanical degeneration. In conclusion, the dual contrast method allowed detection of injuries and degeneration simultaneously with accurate cartilage segmentation using a single scan conducted at 45 min after contrast agent administration.
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Affiliation(s)
- Annina E A Saukko
- Department of Applied Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland.
- Diagnostic Imaging Center, Kuopio University Hospital, POB 100, 70029, Kuopio, Finland.
| | - Juuso T J Honkanen
- Department of Applied Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland
- Diagnostic Imaging Center, Kuopio University Hospital, POB 100, 70029, Kuopio, Finland
| | - Wujun Xu
- Department of Applied Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland
| | - Sami P Väänänen
- Department of Applied Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland
- Department of Orthopaedics, Traumatology and Hand Surgery, Kuopio University Hospital, POB 100, 70029, Kuopio, Finland
| | - Jukka S Jurvelin
- Department of Applied Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland
| | - Vesa-Pekka Lehto
- Department of Applied Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland
| | - Juha Töyräs
- Department of Applied Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland
- Diagnostic Imaging Center, Kuopio University Hospital, POB 100, 70029, Kuopio, Finland
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18
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Oh DJ, Lakin BA, Stewart RC, Wiewiorski M, Freedman JD, Grinstaff MW, Snyder BD. Contrast-enhanced CT imaging as a non-destructive tool for ex vivo examination of the biochemical content and structure of the human meniscus. J Orthop Res 2017; 35:1018-1028. [PMID: 27302693 DOI: 10.1002/jor.23337] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2015] [Accepted: 06/05/2016] [Indexed: 02/04/2023]
Abstract
The biochemical and histopathological techniques used to investigate meniscal content and structure are destructive and time-consuming. Therefore, this study evaluated whether contrast-enhanced computed tomography (CECT) attenuation and contrast agent flux using the iodinated contrast agents CA4+ and ioxaglate correlate with the glycosaminoglycan (GAG) content/distribution and water content in human menisci. The optimal ioxaglate and CA4+ contrast agent concentrations for mapping meniscal GAG distribution were qualitatively determined by comparison of CECT color maps with Safranin-O stained histological sections. The associations between CECT attenuation and GAG content, CECT attenuation and water content, and flux and water content at various time points were determined using both contrast agents. Depth-wise analyses were also performed through each of the native surfaces to examine differences in contrast agent diffusion kinetics and equilibrium partitioning. The optimal concentrations for GAG depiction for ioxaglate and CA4+ were ≥80 and 12 mgI/ml, respectively. Using these concentrations, weak to moderate associations were found between ioxaglate attenuation and GAG content at all diffusion time points (1-48 h), while strong and significant associations were observed between CA4+ attenuation and GAG content as early as 7 h (R2 ≥ 0.67), being strongest at the equilibrium time point (48 h, R2 = 0.81). CECT attenuation for both agents did not significantly correlate with water content, but CA4+ flux correlated with water content (R2 = 0.56-0.64). CECT is a promising, non-destructive imaging technique for ex vivo assessment of meniscal GAG concentration and water content compared to traditional biochemical and histopathological methods. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1018-1028, 2017.
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Affiliation(s)
- Daniel J Oh
- Harvard-MIT Health Sciences and Technology Program, Harvard Medical School, Cambridge, Massachusetts.,Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Harvard Medical School, 1 Overland Street, RN 115, Boston, Massachusetts, 02215
| | - Benjamin A Lakin
- Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Harvard Medical School, 1 Overland Street, RN 115, Boston, Massachusetts, 02215.,Department of Biomedical Engineering, Boston University, 590 Commonwealth Ave, Boston, Massachusetts, 02215
| | - Rachel C Stewart
- Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Harvard Medical School, 1 Overland Street, RN 115, Boston, Massachusetts, 02215.,Department of Biomedical Engineering, Boston University, 590 Commonwealth Ave, Boston, Massachusetts, 02215
| | - Martin Wiewiorski
- Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Harvard Medical School, 1 Overland Street, RN 115, Boston, Massachusetts, 02215.,Department of Orthopaedic and Trauma, Kantonsspital Winterthur, Winterthur, Switzerland
| | - Jonathan D Freedman
- Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Harvard Medical School, 1 Overland Street, RN 115, Boston, Massachusetts, 02215.,Department of Pharmacology and Experimental Therapeutics, Boston University, Boston, Massachusetts
| | - Mark W Grinstaff
- Department of Biomedical Engineering, Boston University, 590 Commonwealth Ave, Boston, Massachusetts, 02215.,Department of Chemistry, Boston University, Boston, Massachusetts
| | - Brian D Snyder
- Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Harvard Medical School, 1 Overland Street, RN 115, Boston, Massachusetts, 02215.,Children's Hospital, Boston, Massachusetts
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19
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Arbabi V, Pouran B, Zadpoor AA, Weinans H. An Experimental and Finite Element Protocol to Investigate the Transport of Neutral and Charged Solutes across Articular Cartilage. J Vis Exp 2017. [PMID: 28518064 DOI: 10.3791/54984] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Osteoarthritis (OA) is a debilitating disease that is associated with degeneration of articular cartilage and subchondral bone. Degeneration of articular cartilage impairs its load-bearing function substantially as it experiences tremendous chemical degradation, i.e. proteoglycan loss and collagen fibril disruption. One promising way to investigate chemical damage mechanisms during OA is to expose the cartilage specimens to an external solute and monitor the diffusion of the molecules. The degree of cartilage damage (i.e. concentration and configuration of essential macromolecules) is associated with collisional energy loss of external solutes while moving across articular cartilage creates different diffusion characteristics compared to healthy cartilage. In this study, we introduce a protocol, which consists of several steps and is based on previously developed experimental micro-Computed Tomography (micro-CT) and finite element modeling. The transport of charged and uncharged iodinated molecules is first recorded using micro-CT, which is followed by applying biphasic-solute and multiphasic finite element models to obtain diffusion coefficients and fixed charge densities across cartilage zones.
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Affiliation(s)
- Vahid Arbabi
- Department of Biomechanical Engineering, Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft); Department of Orthopedics, UMC Utrecht;
| | - Behdad Pouran
- Department of Biomechanical Engineering, Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft); Department of Orthopedics, UMC Utrecht;
| | - Amir A Zadpoor
- Department of Biomechanical Engineering, Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft)
| | - Harrie Weinans
- Department of Biomechanical Engineering, Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft); Department of Orthopedics, UMC Utrecht; Department of Rheumatology, UMC Utrecht
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20
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Rieppo L, Kokkonen HT, Kulmala KAM, Kovanen V, Lammi MJ, Töyräs J, Saarakkala S. Infrared microspectroscopic determination of collagen cross-links in articular cartilage. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:35007. [PMID: 28290599 DOI: 10.1117/1.jbo.22.3.035007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 02/22/2017] [Indexed: 06/06/2023]
Abstract
Collagen forms an organized network in articular cartilage to give tensile stiffness to the tissue. Due to its long half-life, collagen is susceptible to cross-links caused by advanced glycation end-products. The current standard method for determination of cross-link concentrations in tissues is the destructive high-performance liquid chromatography (HPLC). The aim of this study was to analyze the cross-link concentrations nondestructively from standard unstained histological articular cartilage sections by using Fourier transform infrared (FTIR) microspectroscopy. Half of the bovine articular cartilage samples ( n = 27 ) were treated with threose to increase the collagen cross-linking while the other half ( n = 27 ) served as a control group. Partial least squares (PLS) regression with variable selection algorithms was used to predict the cross-link concentrations from the measured average FTIR spectra of the samples, and HPLC was used as the reference method for cross-link concentrations. The correlation coefficients between the PLS regression models and the biochemical reference values were r = 0.84 ( p < 0.001 ), r = 0.87 ( p < 0.001 ) and r = 0.92 ( p < 0.001 ) for hydroxylysyl pyridinoline (HP), lysyl pyridinoline (LP), and pentosidine (Pent) cross-links, respectively. The study demonstrated that FTIR microspectroscopy is a feasible method for investigating cross-link concentrations in articular cartilage.
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Affiliation(s)
- Lassi Rieppo
- University of Oulu, Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, Oulu, FinlandbUniversity of Eastern Finland, Department of Applied Physics, Kuopio, Finland
| | - Harri T Kokkonen
- South Karelia Central Hospital, Department of Radiology, Lappeenranta, Finland
| | | | - Vuokko Kovanen
- University of Jyväskylä, Department of Health Sciences, Jyväskylä, Finland
| | - Mikko J Lammi
- Umeå University, Department of Integrative Medical Biology, Umeå, SwedenfHealth Science Center of Xi'an Jiaotong University, School of Public Health, Key Laboratory of Trace Elements and Endemic Diseases, National Health and Family Planning Commission, Xi'an, China
| | - Juha Töyräs
- University of Eastern Finland, Department of Applied Physics, Kuopio, FinlandgKuopio University Hospital, Diagnostic Imaging Center, Kuopio, Finland
| | - Simo Saarakkala
- University of Oulu, Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, Oulu, FinlandhOulu University Hospital, Department of Diagnostic Radiology, Oulu, FinlandiUniversity of Oulu and Oulu University Hospital, Medical Research Center Oulu, Oulu, Finland
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21
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Isolated effects of external bath osmolality, solute concentration, and electrical charge on solute transport across articular cartilage. Med Eng Phys 2016; 38:1399-1407. [DOI: 10.1016/j.medengphy.2016.09.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 06/19/2016] [Accepted: 09/15/2016] [Indexed: 11/21/2022]
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22
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Honkanen JTJ, Turunen MJ, Freedman JD, Saarakkala S, Grinstaff MW, Ylärinne JH, Jurvelin JS, Töyräs J. Cationic Contrast Agent Diffusion Differs Between Cartilage and Meniscus. Ann Biomed Eng 2016; 44:2913-2921. [PMID: 27129372 PMCID: PMC5042996 DOI: 10.1007/s10439-016-1629-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 04/22/2016] [Indexed: 12/31/2022]
Abstract
Contrast enhanced computed tomography (CECT) is a non-destructive imaging technique used for the assessment of composition and structure of articular cartilage and meniscus. Due to structural and compositional differences between these tissues, diffusion and distribution of contrast agents may differ in cartilage and meniscus. The aim of this study is to determine the diffusion kinematics of a novel iodine based cationic contrast agent (CA(2+)) in cartilage and meniscus. Cylindrical cartilage and meniscus samples (d = 6 mm, h ≈ 2 mm) were harvested from healthy bovine knee joints (n = 10), immersed in isotonic cationic contrast agent (20 mgI/mL), and imaged using a micro-CT scanner at 26 time points up to 48 h. Subsequently, normalized X-ray attenuation and contrast agent diffusion flux, as well as water, collagen and proteoglycan (PG) contents in the tissues were determined. The contrast agent distributions within cartilage and meniscus were different. In addition, the normalized attenuation and diffusion flux were higher (p < 0.05) in cartilage. Based on these results, diffusion kinematics vary between cartilage and meniscus. These tissue specific variations can affect the interpretation of CECT images and should be considered when cartilage and meniscus are assessed simultaneously.
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Affiliation(s)
- Juuso T. J. Honkanen
- Department of Applied Physics, University of Eastern Finland, POB 1627, 70211 Kuopio, Finland
- Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland
| | - Mikael J. Turunen
- Department of Applied Physics, University of Eastern Finland, POB 1627, 70211 Kuopio, Finland
| | - Jonathan D. Freedman
- Department of Pharmacology, Boston University School of Medicine, Boston, MA USA
| | - Simo Saarakkala
- Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland
- Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland
- Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland
| | - Mark W. Grinstaff
- Department of Biomedical Engineering, Boston University, Boston, MA USA
- Department of Chemistry, Boston University, Boston, MA USA
| | - Janne H. Ylärinne
- Department of Integrative Medical Biology, University of Umea, Umeå, Sweden
| | - Jukka S. Jurvelin
- Department of Applied Physics, University of Eastern Finland, POB 1627, 70211 Kuopio, Finland
- Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland
| | - Juha Töyräs
- Department of Applied Physics, University of Eastern Finland, POB 1627, 70211 Kuopio, Finland
- Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland
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23
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In Vivo Contrast-Enhanced Cone Beam CT Provides Quantitative Information on Articular Cartilage and Subchondral Bone. Ann Biomed Eng 2016; 45:811-818. [DOI: 10.1007/s10439-016-1730-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 09/07/2016] [Indexed: 12/17/2022]
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24
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Arbabi V, Pouran B, Weinans H, Zadpoor AA. Combined inverse-forward artificial neural networks for fast and accurate estimation of the diffusion coefficients of cartilage based on multi-physics models. J Biomech 2016; 49:2799-2805. [DOI: 10.1016/j.jbiomech.2016.06.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 06/11/2016] [Accepted: 06/18/2016] [Indexed: 10/21/2022]
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25
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Rautiainen J, Nieminen MT, Salo EN, Kokkonen HT, Mangia S, Michaeli S, Gröhn O, Jurvelin JS, Töyräs J, Nissi MJ. Effect of collagen cross-linking on quantitative MRI parameters of articular cartilage. Osteoarthritis Cartilage 2016; 24:1656-64. [PMID: 27143363 DOI: 10.1016/j.joca.2016.04.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 03/31/2016] [Accepted: 04/23/2016] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To investigate the sensitivity of quantitative magnetic resonance imaging (MRI) parameters to increase of collagen cross-linking in articular cartilage, a factor possibly contributing to the aging-related development of osteoarthritis (OA). The issue has not been widely studied although collagen cross-links may significantly affect the evaluation of cartilage imaging outcome. DESIGN Osteochondral samples (n = 14) were prepared from seven bovine patellae. To induce cross-linking, seven samples were incubated in threose while the other seven served as non-treated controls. The specimens were scanned at 9.4 T for T1, T1Gd (dGEMRIC), T2, adiabatic and continuous wave (CW) T1ρ, adiabatic T2ρ and T1sat relaxation times. Specimens from adjacent tissue were identically treated and used for reference to determine biomechanical properties, collagen, proteoglycan and cross-link contents, fixed charge density (FCD), collagen fibril anisotropy and water concentration of cartilage. RESULTS In the threose-treated sample group, cross-links (pentosidine, lysyl pyridinoline (LP)), FCD and equilibrium modulus were significantly (P < 0.05) higher as compared to the non-treated group. Threose treatment resulted in significantly greater T1Gd relaxation time constant (+26%, P < 0.05), although proteoglycan content was not altered. Adiabatic and CW-T1ρ were also significantly increased (+16%, +28%, P < 0.05) while pre-contrast T1 was significantly decreased (-10%, P < 0.05) in the threose group. T2, T2ρ and T1sat did not change significantly. CONCLUSION Threose treatment induced collagen cross-linking and changes in the properties of articular cartilage, which were detected by T1, T1Gd and T1ρ relaxation time constants. Cross-linking should be considered especially when interpreting the outcome of contrast-enhanced MRI in aging populations.
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Affiliation(s)
- J Rautiainen
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland; Medical Research Center Oulu, University of Oulu, Oulu, Finland.
| | - M T Nieminen
- Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland; Medical Research Center Oulu, University of Oulu, Oulu, Finland; Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland.
| | - E-N Salo
- Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland.
| | - H T Kokkonen
- Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland.
| | - S Mangia
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA.
| | - S Michaeli
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA.
| | - O Gröhn
- Department of Neurobiology, A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.
| | - J S Jurvelin
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland.
| | - J Töyräs
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland.
| | - M J Nissi
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland; Medical Research Center Oulu, University of Oulu, Oulu, Finland; Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland.
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26
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Arbabi V, Pouran B, Weinans H, Zadpoor AA. Multiphasic modeling of charged solute transport across articular cartilage: Application of multi-zone finite-bath model. J Biomech 2016; 49:1510-1517. [DOI: 10.1016/j.jbiomech.2016.03.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 03/12/2016] [Accepted: 03/16/2016] [Indexed: 01/14/2023]
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Transport of Iodine Is Different in Cartilage and Meniscus. Ann Biomed Eng 2015; 44:2114-22. [PMID: 26661617 DOI: 10.1007/s10439-015-1513-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 11/13/2015] [Indexed: 12/25/2022]
Abstract
Contrast enhanced computed tomography (CECT) has been proposed for diagnostics of cartilage and meniscus injuries and degeneration. As both tissues may be imaged simultaneously, CECT could provide a method for comprehensive evaluation of knee joint health. Since the composition and structure of cartilage and meniscus are different, we hypothesize that transport characteristics of anionic contrast agents also differ between the tissues. This would affect interpretation of CECT images and warrants investigation. To clarify this, we aimed to determine the transport kinematics of anionic iodine (q = -1, M = 126.9 g/mol), assumed to not be significantly affected by the steric hindrance, thus providing faster transport than large molecule contrast agents (e.g., ioxaglate). Cylindrical samples (d = 6 mm, h = 2 mm) were prepared from healthy bovine (n = 10) patella and meniscus, immersed in isotonic phosphate-buffered NaI solution (20 mgI/mL), and subsequently imaged with a micro-CT at 20 time points up to 23 h. Subsequently, normalized attenuation and contrast agent flux, as well as water, collagen, and proteoglycan (PG) contents in the tissues were determined. Normalized attenuation at equilibrium was higher (p = 0.005) in meniscus. Contrast agent flux was lower (p = 0.005) in the meniscus at 10 min, but higher (p < 0.05) between 30 and 120 min. In both tissues, contrast agent distribution at equilibrium suggested an inverse agreement with the depth-wise PG distribution. In conclusion, iodine transport into cartilage and meniscus was different, especially between the first 2 hours after the immersion. This is an important finding which should be considered during simultaneous CECT of cartilage and meniscus.
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Turunen MJ, Töyräs J, Kokkonen HT, Jurvelin JS. Quantitative evaluation of knee subchondral bone mineral density using cone beam computed tomography. IEEE TRANSACTIONS ON MEDICAL IMAGING 2015; 34:2186-2190. [PMID: 25935027 DOI: 10.1109/tmi.2015.2426684] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Contrast agent enhanced cone beam computed tomography (CE-CBCT), a technique capable of high-resolution in vivo imaging with small radiation dose, has been applied successfully for clinical diagnostics of cartilage degeneration, i.e., osteoarthritis (OA). As an X-ray technique, CE-CBCT may also detect changes in mineral density of subchondral bone (volumetric bone mineral density, vBMD), known to be characteristic for OA. However, its feasibility for density measurements is not clear due to limited signal-to-noise ratio and contrast of CBCT images. In the present study, we created clinically applicable hydroxyapatite phantoms and determined vBMDs of cortical bone, trabecular bone, subchondral trabecular bone and subchondral plate of 10 cadaver (ex vivo) and 10 volunteer (in vivo) distal femora using a clinical CBCT scanner, and for reference, also using a conventional CT scanner. Our results indicated strong linear correlations between the vBMD values measured with the CT and CBCT scanners , however, absolute vBMD values were dependent on the scanner in use. Further, the differences between the vBMDs of cortical bone, trabecular bone and subchondral bone were similar and independent of the scanner. The present results indicate that vBMD values might not be directly comparable between different instruments. However, based on our present and previous results, we propose that, for OA diagnostics, clinical CBCT enables not only quantitative analysis of articular cartilage but also subchondral bone vBMD. Quantitative information on both cartilage and subchondral bone could be beneficial in OA diagnostics.
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Honkanen JTJ, Danso EK, Suomalainen JS, Tiitu V, Korhonen RK, Jurvelin JS, Töyräs J. Contrast enhanced imaging of human meniscus using cone beam CT. Osteoarthritis Cartilage 2015; 23:1367-76. [PMID: 25865390 DOI: 10.1016/j.joca.2015.03.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 03/06/2015] [Accepted: 03/28/2015] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Meniscal injuries can lead to mechanical overloading of articular cartilage and eventually to knee osteoarthritis. The objective was to evaluate the potential of contrast enhanced computed tomography (CECT) to image contrast agent (CA) diffusion in human menisci with a clinical cone beam CT scanner. DESIGN Isolated human menisci (n = 26) were imaged using magnetic resonance imaging (MRI) and CECT in situ. Diffusion of anionic CA into the meniscus was imaged for up to 30 h. The results of CECT were compared with water, collagen and proteoglycan (PG) contents, biomechanical properties, age and histological and MR images of the samples. RESULTS Diffusion of CA required over 25 h to reach equilibrium. The CA partition (the CA concentration in the tissue divided by that in the bath) at the 40 min time point correlated significantly with that at the 30 h time point in both lateral (r = 0.706, P = 0.007) and medial (r = 0.669, P = 0.012) menisci. Furthermore, CA partition in meniscus after 30 h of diffusion agreed qualitatively with the distribution of PGs. CONCLUSION The cross-sectional distribution of CA was consistent with that reported in a previous μCT study on bovine meniscus. The time required to reach diffusion equilibrium was found impractical for clinical applications. However, based on the present results, shorter delay between injection and imaging (e.g., 40 min) could be feasible in clinical diagnostics of meniscal pathologies.
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Affiliation(s)
- J T J Honkanen
- Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211, Kuopio, Finland; Diagnostic Imaging Centre, Kuopio University Hospital, KUH, POB 100, FI-70029, Kuopio, Finland.
| | - E K Danso
- Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211, Kuopio, Finland; Department of Clinical Neurophysiology, Kuopio University Hospital, KUH, POB 100, FI-70029, Kuopio, Finland.
| | - J-S Suomalainen
- Diagnostic Imaging Centre, Kuopio University Hospital, KUH, POB 100, FI-70029, Kuopio, Finland.
| | - V Tiitu
- Institute of Biomedicine, Anatomy, University of Eastern Finland, POB 1627, FI-70211, Kuopio, Finland.
| | - R K Korhonen
- Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211, Kuopio, Finland; Diagnostic Imaging Centre, Kuopio University Hospital, KUH, POB 100, FI-70029, Kuopio, Finland.
| | - J S Jurvelin
- Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211, Kuopio, Finland; Diagnostic Imaging Centre, Kuopio University Hospital, KUH, POB 100, FI-70029, Kuopio, Finland.
| | - J Töyräs
- Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211, Kuopio, Finland; Diagnostic Imaging Centre, Kuopio University Hospital, KUH, POB 100, FI-70029, Kuopio, Finland.
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Korhonen RK, Tanska P, Kaartinen SM, Fick JM, Mononen ME. New Concept to Restore Normal Cell Responses in Osteoarthritic Knee Joint Cartilage. Exerc Sport Sci Rev 2015; 43:143-52. [DOI: 10.1249/jes.0000000000000051] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Arbabi V, Pouran B, Weinans H, Zadpoor AA. Transport of Neutral Solute Across Articular Cartilage: The Role of Zonal Diffusivities. J Biomech Eng 2015; 137:2210662. [DOI: 10.1115/1.4030070] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Indexed: 02/02/2023]
Abstract
Transport of solutes through diffusion is an important metabolic mechanism for the avascular cartilage tissue. Three types of interconnected physical phenomena, namely mechanical, electrical, and chemical, are all involved in the physics of transport in cartilage. In this study, we use a carefully designed experimental-computational setup to separate the effects of mechanical and chemical factors from those of electrical charges. Axial diffusion of a neutral solute (Iodixanol) into cartilage was monitored using calibrated microcomputed tomography (micro-CT) images for up to 48 hr. A biphasic-solute computational model was fitted to the experimental data to determine the diffusion coefficients of cartilage. Cartilage was modeled either using one single diffusion coefficient (single-zone model) or using three diffusion coefficients corresponding to superficial, middle, and deep cartilage zones (multizone model). It was observed that the single-zone model cannot capture the entire concentration-time curve and under-predicts the near-equilibrium concentration values, whereas the multizone model could very well match the experimental data. The diffusion coefficient of the superficial zone was found to be at least one order of magnitude larger than that of the middle zone. Since neutral solutes were used, glycosaminoglycan (GAG) content cannot be the primary reason behind such large differences between the diffusion coefficients of the different cartilage zones. It is therefore concluded that other features of the different cartilage zones such as water content and the organization (orientation) of collagen fibers may be enough to cause large differences in diffusion coefficients through the cartilage thickness.
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Affiliation(s)
- V. Arbabi
- Department of Biomechanical Engineering, Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, Delft 2628CD, The Netherlands e-mail:
| | - B. Pouran
- Department of Orthopedics, UMC Utrecht, Heidelberglaan 100, Utrecht 3584CX, The Netherlands
- Department of Biomechanical Engineering, Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, Delft 2628CD, The Netherlands
| | - H. Weinans
- Department of Orthopedics and Department of Rheumatology, UMC Utrecht, Heidelberglaan 100, Utrecht 3584CX, The Netherlands
- Department of Biomechanical Engineering, Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628CD, Delft, The Netherlands
| | - A. A. Zadpoor
- Department of Biomechanical Engineering, Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, Delft 2628CD, The Netherlands
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Entezari V, Bansal PN, Stewart RC, Lakin BA, Grinstaff MW, Snyder BD. Effect of mechanical convection on the partitioning of an anionic iodinated contrast agent in intact patellar cartilage. J Orthop Res 2014; 32:1333-40. [PMID: 24961833 DOI: 10.1002/jor.22662] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Accepted: 05/14/2014] [Indexed: 02/04/2023]
Abstract
To determine if mechanical convection accelerates partitioning of an anionic contrast agent into cartilage while maintaining its ability to reflect the glycosaminoglycan (GAG) content in contrast-enhanced computed tomography (CECT) of cartilage. Bovine patellae (N = 4) were immersed in iothalamate and serially imaged over 24 h of passive diffusion at 34°C. Following saline washing for 14 h, each patella was serially imaged over 2.5 h of mechanical convection by cyclic compressive loading (120N, 1 Hz) while immersed in iothalamate at 34°C. After similar saline washing, each patella was sectioned into 15 blocks (n = 60) and contrast concentration per time point as well as GAG content were determined for each cartilage block. Mechanical convection produced 70.6%, 34.4%, and 16.4% higher contrast concentration at 30, 60, and 90 min, respectively, compared to passive diffusion (p < 0.001) and boosted initial contrast flux 330%. The correlation between contrast concentration and GAG content was significant at all time points and correlation coefficients improved with time, reaching R(2) = 0.60 after 180 min of passive diffusion and 22.5 min of mechanical convection. Mechanical convection significantly accelerated partitioning of a contrast agent into healthy cartilage while maintaining strong correlations with GAG content, providing an evidence-based rationale for adopting walking regimens in CECT imaging protocols.
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Affiliation(s)
- Vahid Entezari
- Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, 02215
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Fick JM, Huttu MRJ, Lammi MJ, Korhonen RK. In vitro glycation of articular cartilage alters the biomechanical response of chondrocytes in a depth-dependent manner. Osteoarthritis Cartilage 2014; 22:1410-8. [PMID: 25278052 DOI: 10.1016/j.joca.2014.07.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 07/16/2014] [Accepted: 07/18/2014] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To determine if increasing cartilage cross-links through in vitro glycation of cartilage explants can alter the biomechanical response of chondrocytes to compressive deformation. METHOD Bovine osteochondral explants were either incubated with cell culture solution supplemented with (n = 7) or without (n = 7) ribose for 42 h in order to induce glycation. Deformation-induced changes in cell volume, dimensions and local tissue strains were determined through confocal laser scanning microscopy (CLSM) and the use of a custom built micro-compression device. Osteochondral explants were also utilized to demonstrate changes in depth-wise tissue properties, biomechanical tissue properties and cross-links such as pentosidine (Pent), hydroxylysyl pyridinoline (HP) and lysyl pyridinoline (LP). RESULTS The ribose treated osteochondral samples experienced reduced cell volume deformation in the upper tissue zone by ∼ 8% (P = 0.005), as compared the control samples, through restricting cell expansion. In the deeper tissue zone, cell volume deformation was increased by ∼ 12% (P < 0.001) via the transmission of mechanical signals further into the tissue depth. Biomechanical testing of the ribose treated osteochondral samples demonstrated an increase in the equilibrium and dynamic strain dependent moduli (P < 0.001 and P = 0.008, respectively). The biochemical analysis revealed an increase in Pent cross-links (P < 0.001). Depth-wise tissue property analyses revealed increased levels of carbohydrate content, greater levels of fixed charge density and an increased carbohydrate to protein ratio from 6 to 16%, 55-100% and 72-79% of the normalized tissue thickness (from the surface), respectively, in the ribose-treated group (P < 0.05). CONCLUSION In vitro glycation alters the biomechanical response of chondrocytes in cartilage differently in upper and deeper zones, offering possible insights into how aging could alter cell deformation behavior in cartilage.
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Affiliation(s)
- J M Fick
- Department of Applied Physics, University of Eastern Finland, Kuopio FI-70211, Finland.
| | - M R J Huttu
- Department of Applied Physics, University of Eastern Finland, Kuopio FI-70211, Finland
| | - M J Lammi
- Department of Applied Physics, University of Eastern Finland, Kuopio FI-70211, Finland
| | - R K Korhonen
- Department of Applied Physics, University of Eastern Finland, Kuopio FI-70211, Finland
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Decker SGA, Moeini M, Chin HC, Rosenzweig DH, Quinn TM. Adsorption and distribution of fluorescent solutes near the articular surface of mechanically injured cartilage. Biophys J 2014; 105:2427-36. [PMID: 24268155 DOI: 10.1016/j.bpj.2013.09.037] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 07/29/2013] [Accepted: 09/04/2013] [Indexed: 11/26/2022] Open
Abstract
The development of cartilage-specific imaging agents supports the improvement of tissue assessment by minimally invasive means. Techniques for highlighting cartilage surface damage in clinical images could provide for sensitive indications of posttraumatic injury and early stage osteoarthritis. Previous studies in our laboratory have demonstrated that fluorescent solutes interact with cartilage surfaces strongly enough to affect measurement of their partition coefficients within the tissue bulk. In this study, these findings were extended by examining solute adsorption and distribution near the articular surface of mechanically injured cartilage. Using viable cartilage explants injured by an established protocol, solute distributions near the articular surface of three commonly used fluorophores (fluorescein isothiocyanate (FITC), tetramethylrhodamine isothiocyanate (TRITC), and carboxytetramethylrhodamine (TAMRA)) were observed after absorption and subsequent desorption to assess solute-specific matrix interactions and reversibility. Both absorption and desorption processes demonstrated a trend of significantly less solute adsorption at surfaces of fissures compared to adjacent intact surfaces of damaged explants or surfaces of uninjured explants. After adsorption, normalized mean surface intensities of fissured surfaces of injured explants were 6%, 40%, and 32% for FITC, TRITC, and TAMRA, respectively, compared to uninjured surfaces. Similar values were found for sliced explants and after a desorption process. After desorption, a trend of increased solute adsorption at the site of intact damaged surfaces was noted (316% and 238% for injured and sliced explants exposed to FITC). Surface adsorption of solute was strongest for FITC and weakest for TAMRA; no solutes negatively affected cell viability. Results support the development of imaging agents that highlight distinct differences between fissured and intact cartilage surfaces.
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Affiliation(s)
- Sarah G A Decker
- Department of Chemical Engineering, McGill University, Montreal, QC, Canada
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Abstract
Objectives Our objective in this article is to test the hypothesis that
type 2 diabetes mellitus (T2DM) is a factor in the onset and progression
of osteoarthritis, and to characterise the quality of the articular
cartilage in an appropriate rat model. Methods T2DM rats were obtained from the UC Davis group and compared
with control Lewis rats. The diabetic rats were sacrificed at ages
from six to 12 months, while control rats were sacrificed at six
months only. Osteoarthritis severity was determined via histology
in four knee quadrants using the OARSI scoring guide. Immunohistochemical
staining was also performed as a secondary form of osteoarthritic
analysis. Results T2DM rats had higher mean osteoarthritis scores than the control
rats in each of the four areas that were analysed. However, only
the results at the medial and lateral femur and medial tibia were
significant. Cysts were also found in T2DM rats at the junction
of the articular cartilage and subchondral bone. Immunohistochemical
analysis does not show an increase in collagen II between control
and T2DM rats. Mass comparisons also showed a significant relationship
between mass and osteoarthritis score. Conclusions T2DM was found to cause global degeneration in the UCD rat knee
joints, suggesting that diabetes itself is a factor in the onset
and progression of osteoarthritis. The immunohistochemistry stains
showed little to no change in collagen II degeneration between T2DM
and control rats. Overall, it seems that the animal model used is
pertinent to future studies of T2DM in the development and progression
of osteoarthritis. Cite this article: Bone Joint Res 2014;3:203–11
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Affiliation(s)
- T Onur
- University of California, 4150 Clement Street Surgery 112, San Francisco, California 94121, USA
| | - R Wu
- University of California, 4150 Clement Street Surgery 112, San Francisco, California 94121, USA
| | - L Metz
- University of California, 500 Parnassus Ave MU320w, San Francisco, California 94143, USA
| | - A Dang
- University of California, 4150 Clement Street Surgery 112, San Francisco, California 94121, USA
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Huttu M, Turunen S, Sokolinski V, Tiitu V, Lammi M, Korhonen RK. Effects of medium and temperature on cellular responses in the superficial zone of hypo-osmotically challenged articular cartilage. J Funct Biomater 2014; 3:544-55. [PMID: 23807905 PMCID: PMC3691548 DOI: 10.3390/jfb3030544] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Osmotic loading of articular cartilage has been used to study cell-tissue interactions and mechanisms in chondrocyte volume regulation in situ. Since cell volume changes are likely to affect cell’s mechanotransduction, it is important to understand how environmental factors, such as composition of the immersion medium and temperature affect cell volume changes in situ in osmotically challenged articular cartilage. In this study, chondrocytes were imaged in situ with a confocal laser scanning microscope (CLSM) through cartilage surface before and 3 min and 120 min after a hypo-osmotic challenge. Samples were measured either in phosphate buffered saline (PBS, without glucose and Ca2+) or in Dulbecco’s modified Eagle’s medium (DMEM, with glucose and Ca2+), and at 21 °C or at 37 °C. In all groups, cell volumes increased shortly after the hypotonic challenge and then recovered back to the original volumes. At both observation time points, cell volume changes as a result of the osmotic challenge were similar in PBS and DMEM in both temperatures. Our results indicate that the initial chondrocyte swelling and volume recovery as a result of the hypo-osmotic challenge of cartilage are not dependent on commonly used immersion media or temperature.
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Affiliation(s)
- Mari Huttu
- Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, Kuopio FI-70211, Finland; (M.H.); (S.T.);
(V.S.); (R.K.)
| | - Siru Turunen
- Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, Kuopio FI-70211, Finland; (M.H.); (S.T.);
(V.S.); (R.K.)
| | - Viktoria Sokolinski
- Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, Kuopio FI-70211, Finland; (M.H.); (S.T.);
(V.S.); (R.K.)
| | - Virpi Tiitu
- Institute of Biomedicine, University of Eastern Finland, P.O. Box 1627, Kuopio FI-70211, Finland;
- SIB-Labs, University of Eastern Finland, P.O. Box 1627, Kuopio FI-70211, Finland
| | - Mikko Lammi
- Institute of Biomedicine, University of Eastern Finland, P.O. Box 1627, Kuopio FI-70211, Finland;
- Biocenter Kuopio, University of Eastern Finland, P.O. Box 1627, Kuopio FI-70211, Finland
- Author to whom correspondence should be addressed; ; Tel.: +358-40-355-3027; Fax: +358-17-162-131
| | - Rami K. Korhonen
- Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, Kuopio FI-70211, Finland; (M.H.); (S.T.);
(V.S.); (R.K.)
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Kokkonen HT, Suomalainen JS, Joukainen A, Kröger H, Sirola J, Jurvelin JS, Salo J, Töyräs J. In vivo diagnostics of human knee cartilage lesions using delayed CBCT arthrography. J Orthop Res 2014; 32:403-12. [PMID: 24249683 DOI: 10.1002/jor.22521] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 10/21/2013] [Indexed: 02/04/2023]
Abstract
The aim of this study was to investigate the feasibility of delayed cone beam (CBCT) arthrography for clinical diagnostics of knee cartilage lesions. Knee joints with cartilage lesions were imaged using native radiography, MRI, and delayed CBCT arthrography techniques in vivo. The joints were imaged three times with CBCT, just before, immediately after (arthrography) and 45 min after the intra-articular injection of contrast agent. The arthrographic images enabled sensitive detection of the cartilage lesions. Use of arthrographic and delayed images together with their subtraction image enabled also detection of cartilage with inferior integrity. The contrast agent partition in intact cartilage (ICRS grade 0) was lower (p < 0.05) than that of cartilage surrounding the ICRS grade I-IV lesions. Delayed CBCT arthrography provides a novel method for diagnostics of cartilage lesions. Potentially, it can also be used in diagnostics of cartilage degeneration. Due to shorter imaging times, higher resolution, and lower costs of CT over MRI, this technique could provide an alternative for diagnostics of knee pathologies. However, for comprehensive evaluation of the clinical potential of the technique a further clinical study with a large pool of patients having a wide range of cartilage pathologies needs to be conducted.
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Affiliation(s)
- Harri T Kokkonen
- Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland
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Kulmala KAM, Karjalainen HM, Kokkonen HT, Tiitu V, Kovanen V, Lammi MJ, Jurvelin JS, Korhonen RK, Töyräs J. Diffusion of ionic and non-ionic contrast agents in articular cartilage with increased cross-linking--contribution of steric and electrostatic effects. Med Eng Phys 2013; 35:1415-20. [PMID: 23622944 DOI: 10.1016/j.medengphy.2013.03.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 01/15/2013] [Accepted: 03/14/2013] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To investigate the effect of threose-induced collagen cross-linking on diffusion of ionic and non-ionic contrast agents in articular cartilage. DESIGN Osteochondral plugs (Ø=6mm) were prepared from bovine patellae and divided into two groups according to the contrast agent to be used in contrast enhanced computed tomography (CECT) imaging: (I) anionic ioxaglate and (II) non-ionic iodixanol. The groups I and II contained 7 and 6 sample pairs, respectively. One of the paired samples served as a reference while the other was treated with threose to induce collagen cross-linking. The equilibrium partitioning of the contrast agents was imaged after 24h of immersion. Fixed charge density (FCD), water content, contents of proteoglycans, total collagen, hydroxylysyl pyridinoline (HP), lysyl pyridinoline (LP) and pentosidine (Pent) cross-links were determined as a reference. RESULTS The equilibrium partitioning of ioxaglate (group I) was significantly (p=0.018) lower (-23.4%) in threose-treated than control samples while the equilibrium partitioning of iodixanol (group II) was unaffected by the threose-treatment. FCD in the middle and deep zones of the cartilage (p<0.05) and contents of Pent and LP (p=0.001) increased significantly due to the treatment. However, the proteoglycan concentration was not systematically altered after the treatment. Water content was significantly (-3.5%, p=0.007) lower after the treatment. CONCLUSIONS Since non-ionic iodixanol showed no changes in partition after cross-linking, in contrast to anionic ioxaglate, we conclude that the cross-linking induced changes in charge distribution have greater effect on diffusion compared to the cross-linking induced changes in steric hindrance.
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Affiliation(s)
- K A M Kulmala
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
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Yusuf KQ, Momot KI, Wellard RM, Oloyede A. A study of the diffusion characteristics of normal, delipidized and relipidized articular cartilage using magnetic resonance imaging. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2013; 24:1005-1013. [PMID: 23404060 DOI: 10.1007/s10856-013-4858-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2012] [Accepted: 01/18/2013] [Indexed: 06/01/2023]
Abstract
This paper assesses the capacity to provide semipermeability of the synthetic layer of surface-active phospholipids created to replace the depleted surface amorphous layer of articular cartilage. The surfaces of articular cartilage specimens in normal, delipidized, and relipidized conditions following incubation in dipalmitoyl-phosphatidylcholine and palmitoyl-oleoyl-phosphatidylcholine components of the joint lipid mixture were characterized nanoscopically with the atomic force microscope and also imaged as deuterium oxide (D2O) diffused transiently through these surfaces in a magnetic resonance imaging enclosure. The MR images were then used to determine the apparent diffusion coefficients in a purpose-built MATLAB(®)-based algorithm. Our results revealed that all surfaces were permeable to D2O, but that there was a significant difference in the semipermeability of the surfaces under the different conditions, relative to the apparent diffusion coefficients. Based on the results and observations, it can be concluded that the synthetic lipid that is deposited to replace the depleted SAL of articular cartilage is capable of inducing some level of semipermeability.
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Affiliation(s)
- K Q Yusuf
- School of Chemistry, Physical and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, Brisbane, QLD, Australia
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Hirvasniemi J, Kulmala KAM, Lammentausta E, Ojala R, Lehenkari P, Kamel A, Jurvelin JS, Töyräs J, Nieminen MT, Saarakkala S. In vivo comparison of delayed gadolinium-enhanced MRI of cartilage and delayed quantitative CT arthrography in imaging of articular cartilage. Osteoarthritis Cartilage 2013; 21:434-42. [PMID: 23274105 DOI: 10.1016/j.joca.2012.12.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 10/23/2012] [Accepted: 12/16/2012] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To compare delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) and delayed quantitative computed tomography (CT) arthrography (dQCTA) to each other, and their association to arthroscopy. Additionally, the relationship between dGEMRIC with intravenous (dGEMRIC(IV)) and intra-articular contrast agent administration (dGEMRIC(IA)) was determined. DESIGN Eleven patients with knee pain were scanned at 3 T MRI and 64-slice CT before arthroscopy. dQCTA was performed at 5 and 45 min after intra-articular injection of ioxaglate. Both dGEMRIC(IV) and dGEMRIC(IA) were performed at 90 min after gadopentetate injection. dGEMRIC indices and change in relaxation rates (ΔR(1)) were separately calculated for dGEMRIC(IV) and dGEMRIC(IA). dGEMRIC and dQCTA parameters were calculated for predetermined sites at the knee joint that were International Cartilage Repair Society (ICRS) graded in arthroscopy. RESULTS dQCTA normalized with the contrast agent concentration in synovial fluid (SF) and dGEMRIC(IV) correlated significantly, whereas dGEMRIC(IA) correlated with the normalized dQCTA only when dGEMRIC(IA) was also normalized with the contrast agent concentration in SF. Correlation was strongest between normalized dQCTA at 45 min and ΔR(1,IV) (r(s) = 0.72 [95% CI 0.56-0.83], n = 49, P < 0.01) and ΔR(1,IA) normalized with ΔR(1) in SF (r(s) = 0.70 [0.53-0.82], n = 52, P < 0.01). Neither dGEMRIC nor dQCTA correlated with arthroscopic grading. dGEMRIC(IV) and non-normalized dGEMRIC(IA) were not related while ΔR(1,IV) correlated with normalized ΔR(1,IA) (r(s) = 0.52 [0.28-0.70], n = 50, P < 0.01). CONCLUSIONS This study suggests that dQCTA is in best agreement with dGEMRIC(IV) at 45 min after CT contrast agent injection. dQCTA and dGEMRIC were not related to arthroscopy, probably because the remaining cartilage is analysed in dGEMRIC and dQCTA, whereas in arthroscopy the absence of cartilage defines the grading. The findings indicate the importance to take into account the contrast agent concentration in SF in dQCTA and dGEMRIC(IA).
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Affiliation(s)
- J Hirvasniemi
- Department of Medical Technology, University of Oulu, Oulu, Finland.
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Silvast TS, Jurvelin JS, Tiitu V, Quinn TM, Töyräs J. Bath Concentration of Anionic Contrast Agents Does Not Affect Their Diffusion and Distribution in Articular Cartilage In Vitro. Cartilage 2013; 4:42-51. [PMID: 26069649 PMCID: PMC4297109 DOI: 10.1177/1947603512451023] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE Differences in contrast agent diffusion reflect changes in composition and structure of articular cartilage. However, in clinical application the contrast agent concentration in the joint capsule varies, which may affect the reliability of contrast enhanced cartilage tomography (CECT). In the present study, effects of concentration of x-ray contrast agents on their diffusion and equilibrium distribution in cartilage were investigated. DESIGN Full-thickness cartilage discs (d = 4.0 mm, n = 120) were detached from bovine patellae (n = 24). The diffusion of various concentrations of ioxaglate (5, 10, 21, 50 mM) and iodide (30, 60, 126, 300 mM) was allowed only through the articular surface. Samples were imaged with a clinical peripheral quantitative computed tomography scanner before immersion in contrast agent, and after 1, 5, 9, 16, 25, and 29 hours in the bath. RESULTS Diffusion and partition coefficients were similar between different contrast agent concentrations. The diffusion coefficient of iodide (473 ± 133 µm(2)/s) was greater (P ≤ 0.001) than that of ioxaglate (92 ± 46 µm(2)/s). In full-thickness cartilage, the partition coefficient (at 29 h) of iodide (71 ± 5%) was greater (P ≤ 0.02 with most concentrations) than that of ioxaglate (62 ± 6%). CONCLUSIONS Significant differences in partition and diffusion coefficient of two similarly charged (-1) contrast agents were detected, which shows the effect of steric interactions. However, the increase in solute concentration did not increase its partition coefficient. In clinical application, it is important that contrast agent concentration does not affect the interpretation of CECT imaging.
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Affiliation(s)
- Tuomo S. Silvast
- SIB-Labs, University of Eastern Finland, Kuopio, Finland,Department of Applied Physics, University of Eastern Finland, Kuopio, Finland,Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland
| | - Jukka S. Jurvelin
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
| | - Virpi Tiitu
- Institute of Biomedicine, Anatomy, University of Eastern Finland, Kuopio, Finland
| | - Thomas M. Quinn
- Department of Chemical Engineering, McGill University, Montreal, Canada
| | - Juha Töyräs
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland,Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland
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