Imaging of the disease process

Radiological osteoarthritic knee joint changes in high school and collegiate sumo wrestlers: The observational study

We examined the effects of sumo on their knee joints, and investigated the relationship between radiological changes and knee joints symptoms, and the relationship between knee radiological changes and the physical characteristics of the wrestlers. Fifty-six high-school and 128 college freshman sumo wrestlers who belonged to the Japanese Sumo Federation. To evaluate radiological changes in the knee joints of high-school and college freshmen sumo wrestlers. They underwent routine radiographic examination of their knee joints and were instructed to answer a questionnaire regarding their knee symptoms as a medical check. The mean height, weight, body mass index (BMI), and sumo career/experience of the participants were 174.1 cm, 106.9 kg, 35.1 kg/m2, and 7.9 years, respectively. Twenty-five high-school (44.6%) and 54 collegiate (42.2%) sumo wrestlers had some knee symptoms, which was significantly associated with sumo career as a risk factor. Five high-school (8.9 %) and 18 collegiate (14.1 %) sumo wrestlers had joint space narrowing. Considering the relationship between knee symptoms and radiological changes, significant correlations between osteophyte formation and bony sclerosis and knee symptoms were observed. According to the Kellgren-Laurence (KL) classification, 7 high-school (12.5%) and 26 collegiate (20.3%) sumo wrestlers were grade 2, 3, or 4. The risk factors of degenerative radiographic changes in the knee joints of the participants were heavyweight, large BMI, and older age. The knee osteoarthritic changes had already appeared in 12.5% high-school sumo wrestlers at the admission.

Phytochemical Screening and Evaluation of the Antiarthritic Potentialof Ammoides pusilla Aqueous Extract on Freund's Adjuvant-Induced Rheumatoid Arthritis

Background: Ammoides pusilla plant is a species of therapeutic interest which used in traditional medicines. This work aims to valorize this plant by the characterization of their bioactive components and the evaluation of the in vivo anti-inflammatory potential against a severe disease affecting the bone structure and the stability of the articular cartilage. Methods: First, the phytochemical screening of the polyphenolic extracts of A. pusilla was carried out. The second part of our study is devoted to the evaluation of the in vivo anti-inflammatory activity of the aqueous extract of A. pusilla based on the method of Freund's adjuvant-induced rheumatoid arthritis. Results: Phytochemical tests demonstrated the richness of extract with flavonoids, tannins, coumarins, anthocyanins and triterpenes. Whereas, the quantitative determination reveals that the aqueous extract of A. pusilla is the richest with bioactive components with contents of total polyphenols, flavonoids and tannins equal to 9.52 ± 0.11 mg gallic acid/g, 4.75 ± 0.05 mg quercetin/g and 8.64 ± 0.02 mg catechin/g respectively. The results of the anti-inflammatory activity showed that the aqueous infused extract of A. pusilla has an interesting antiarthritic potential on Freund's adjuvant-induced rheumatoid arthritis in mice. It is manifested by a weight gain; a normal arthritic index and biochemical parameters close to those of Diclofenac®. Conclusion: The aqueous infused extract of A. pusilla is therefore of considerable therapeutic interest as an alternative compound for the prevention of inflammation and for the improvement in bone structure.

Standardized, musculoskeletal ultrasonographic reference values for healthy Korean adults

BACKGROUND/AIMS

To define standard reference values for musculoskeletal ultrasonography (MSUS) in Korea.

METHODS

A total of 251 healthy adults were recruited for this study. Ultrasonography was performed by experienced rheumatologists who had undergone four appropriate training programs in Korea. A General Electric LOGIQ electronic ultrasound device fitted with a 12 MHz linear transducer was employed. Mean values ± standard deviations (SDs) were defined as standard reference values. Intraclass correlation coefficients was employed to evaluate the extent of inter- and intraobserver agreement when MSUS measurements were made.

RESULTS

The 251 study participants included 122 males. Mean subject age was 28.6 years. The average bone-to-capsule distance of the right-side second and third metacarpophalangeal (MCP) joints were 0.68 and 0.72 mm respectively, and those of the left-side joints 0.62 and 0.68 mm. The cartilage thicknesses of the rightside second and third MCP joints were 0.55 and 0.55 mm, and those of the leftside joints were 0.55 and 0.56 mm, respectively. The bone-to-capsule distances of the right and left wrists were 0.80 and 0.82 mm. In 12.4% of participants (31/251), the erosion score of the humeral head was 1.71. In the right-side knee joint, mean cartilage thicknesses of the medial and lateral condyles were 1.86 and 2.03 mm in longitudinal scans. High overall interobserver agreement was evident after appropriate training that included instruction on standard MSUS methodology.

CONCLUSION

We defined standard reference values for MSUS in healthy Korean adults. The reliabilities of interobserver agreements were high after appropriate training program.

Mapping tibiofemoral gonarthrosis: an MRI analysis of non-traumatic knee cartilage defects

OBJECTIVE

Arthroscopy is "the gold standard" for the diagnosis of knee cartilage lesions. However, it is invasive and expensive, and displays all the potential complications of an open surgical procedure. Ultra-high-field MRI now offers good opportunities for the indirect assessment of the integrity and structural changes of joint cartilage of the knee. The goal of the present study is to determine the site of early cartilaginous lesions in adults with non-traumatic knee pain.

METHODS

3-T MRI examinations of 200 asymptomatic knees with standard and three-dimensional double-echo steady-state (3D-DESS) cartilage-specific sequences were prospectively studied for early degenerative lesions of the tibiofemoral joint. Lesions were classified and mapped using the modified Outerbridge and modified International Cartilage Repair Society classifications.

RESULTS

A total of 1437 lesions were detected: 56.1% grade I, 33.5% grade II, 7.2% grade III and 3.3% grade IV. Cartographically, grade I lesions were most common in the anteromedial tibial areas; grade II lesions in the anteromedial L5 femoral areas; and grade III in the centromedial M2 femoral areas.

CONCLUSION

3-T MRI with standard and 3D-DESS cartilage-specific sequences demonstrated that areas predisposed to early osteoarthritis are the central, lateral and ventromedial tibial plateau, as well as the central and medial femoral condyle.

ADVANCES IN KNOWLEDGE

In contrast with previous studies reporting early cartilaginous lesions in the medial tibial compartment and/or in the medial femoral condyle, this study demonstrates that, regardless of grade, lesions preferentially occur at the L5 and M4 tibial and L5 and L2 femoral areas of the knee joint.

History of knee injury and MRI-assessed knee structures in middle- and older-aged adults: a cross-sectional study

The aim of this cross-sectional study was to describe the associations between history of knee injury and knee structure using magnetic resonance imaging (MRI). This study included two population-based samples: the Tasmanian Older Adult Cohort (TASOAC) study (n = 430; mean age, 63.0 years; range, 51-79 years; 51 % female) and the Offspring study (n = 372; mean age, 45.0 years; range, 26-61 years; 57.5 % female). In both studies, 1.5 T MRI scans of the right knee were performed to measure bone marrow lesions (BMLs), cartilage volume, tibial bone area, cartilage defects and meniscal pathology. History of knee injury was assessed using a self-administered questionnaire. The association between knee injury and knee structure was determined using multiple linear and log binomial regression models. Nineteen percent of the middle-aged and 12 % of the older adults reported a history of knee injury. In middle-aged adults, BML presence (prevalence ratio (PR) = 1.6 (95 % CI, 1.2; 2.1)), tibial bone area (difference of means (DM) = +86 (+23, +149)) and meniscal extrusion presence (PR = 2.7 (1.1, 6.8)) were significantly higher in those with knee injury. In older adults, cartilage defect presence (PR = 1.3 (1.0, 1.7)), lateral (DM = -265 (-439, -92)) and total tibial (DM = -325 (-600, -51)) cartilage volume, BML presence (PR = 1.4 (1.0, 1.9)) and tibial bone area (DM = +140 (+19, +260)) were significantly associated with knee injury. Meniscal tears showed no significant associations in either cohorts. The association between knee injury and MRI-assessed structural pathology in the knee joint is moderate and appears to be stronger in older adults compared to middle-aged adults.

Early T2 changes predict onset of radiographic knee osteoarthritis: data from the osteoarthritis initiative

OBJECTIVE

To evaluate whether T2 relaxation time measurements obtained at 3 T MRI predict the onset of radiographic knee osteoarthritis (OA).

MATERIALS AND METHODS

We performed a nested case-control study of incident radiographic knee OA in the Osteoarthritis Initiative cohort. Cases were 50 knees with baseline Kellgren-Lawrence (KL) grade of 0 that developed KL grade of 2 or more over a 4-year period. Controls were 80 knees with KL grade of 0 after 4 years of follow-up. Baseline T2 relaxation time measurements and laminar analysis of T2 in deep and superficial layers were performed in all knee compartments. The association of T2 values with incident OA was assessed with logistic regression and differences in T2 values by case-control status with linear regression, adjusting for age, sex, body mass index (BMI) and other covariates.

RESULTS

Baseline T2 values in all compartments except the medial tibia were significantly higher in knees that developed OA compared with controls and were particularly elevated in the superficial cartilage layers in all compartments. There was an increased likelihood of incident knee OA associated with higher baseline T2 values, particularly in the patella, adjusted OR per 1 SD increase in T2 (3.37 (95% CI 1.72 to 6.62)), but also in the medial femur (1.90 (1.07 to 3.39)), lateral femur (2.17 (1.11 to 4.25)) and lateral tibia (2.23 (1.16 to 4.31)).

CONCLUSIONS

These findings suggest that T2 values assessed when radiographic changes are not yet apparent may be useful in predicting the development of radiological tibiofemoral OA.

Direct comparison of fixed flexion, radiography and MRI in knee osteoarthritis: responsiveness data from the Osteoarthritis Initiative

OBJECTIVE

Minimum radiographic joint space width (mJSW) represents the Food and Drug Administration (FDA) standard for demonstrating structural therapeutic benefits for knee osteoarthritis (KOA), but only shows moderate responsiveness (sensitivity to change). We directly compare the responsiveness of magnetic resonance imaging (MRI)-based cartilage thickness and JSW measures from fixed-flexion radiography (FFR) and explore the correlation of region-matched changes between both methods.

METHODS

Nine hundred and sixty-seven knees of Osteoarthritis Initiative participants with radiographic KOA were studied: 445 over 1 year with coronal FLASH MRI and FFR, and 375/522 over 1/2 years with sagittal DESS MRI and FFR. Standardized response means (SRM) of cartilage thickness and mJSW were compared using the sign-test.

RESULTS

With FLASH MRI, SRM was -0.28 for medial femorotibial compartment (MFTC) cartilage loss vs -0.15 for mJSW, and -0.32 vs -0.22 for the most sensitive MRI subregion (central MFTC) vs the most sensitive fixed-location JSW(x = 0.25). With DESS MRI, 1-year SRM was -0.34 for MFTC vs -0.22 for mJSW and -0.44 vs -0.28 for central MFTC vs JSW(x = 0.225). Over 2 years, the SRM was significantly greater for MFTC than for mJSW (-0.43 vs -0.31, P = 0.017) and for central MFTC than for JSW(x = 0.225) (-0.51 vs -0.44, P < 0.001). Correlations between changes in spatially matched MRI subregions and fixed-location JSW were not consistently higher (r = 0.10-0.51) than those between non-matched locations (r = 0.15-0.50).

CONCLUSIONS

MRI displays greater responsiveness in KOA than JSW FFR-based JSW, with the greatest SRM observed in the central medial femorotibial compartment. Fixed-location radiographic measures appear not capable of determining the spatial distribution of femorotibial cartilage loss.

MR imaging of articular cartilage physiology

The newer magnetic resonance (MR) imaging methods can give insights into the initiation, progression, and eventual treatment of osteoarthritis. Sodium imaging is specific for changes in proteoglycan (PG) content without the need for an exogenous contrast agent. T1ρ imaging is sensitive to early PG depletion. Delayed gadolinium-enhanced MR imaging has high resolution and sensitivity. T2 mapping is straightforward and is sensitive to changes in collagen and water content. Ultrashort echo time MR imaging examines the osteochondral junction. Magnetization transfer provides improved contrast between cartilage and fluid. Diffusion-weighted imaging may be a valuable tool in postoperative imaging.

Advanced MRI of articular cartilage

Musculoskeletal MRI is advancing rapidly, with innovative technology and significant potential for immediate clinical impact. In particular, cartilage imaging has become a topic of increasing interest as our aging population develops diseases such as osteoarthritis. Advances in MRI hardware and software have led to increased image quality and tissue contrast. Additional developments have allowed the assessment of cartilage macromolecular content, which may be crucial to the early detection of musculoskeletal diseases. This comprehensive article considers current morphological and physiological cartilage imaging techniques, their clinical applications, and their potential to contribute to future improvements in the imaging of cartilage.

Predictive factors for new onset or progression of knee osteoarthritis one year after trauma: MRI follow-up in general practice

Objective

To prospectively evaluate prognostic factors for new onset or progression of degenerative change on follow-up MRI one year after knee trauma and the association with clinical outcome.

Methods

Within a prospective observational cohort study in general practice, we studied a subgroup of 117 patients with acute knee trauma (mean age 41 years, 43% women). Degenerative change was scored on MRI at baseline and after one year follow-up. Multivariate logistic regression analysis was performed to evaluate prognostic factors for new onset or progressive degenerative change on follow-up MRI. Association between new or progressive degeneration and clinical outcome after one year was assessed.

Results

On follow-up MRI 15% of patients with pre-existing knee osteoarthritis showed progression and 26% of patients demonstrated new degenerative change. The only statistically significant prognostic variable in the multivariate analysis was bone marrow oedema on initial MRI (OR 5.29 (95% CI 1.64–17.1), p = 0.005). A significant association between new or progressive degenerative change and clinical outcome was found (p = 0.003).

Conclusion

Bone marrow oedema on MRI for acute knee injury is strongly predictive of new onset or progression of degenerative change of the femorotibial joint on follow-up MRI one year after trauma, which is reflected in clinical outcome.

Aggrecan and cartilage oligomeric matrix protein in serum and synovial fluid of patients with knee osteoarthritis

Aggrecan and cartilage oligomeric matrix protein (COMP) which are important degradation products of articular cartilage may be promising diagnostic markers in serum and/or synovial fluid for diagnosis of knee osteoarthritis (OA). Our objective was to measure serum and synovial fluid levels of aggrecan and COMP in patients with OA of the knee joint to find out if they could be of diagnostic value in OA and if their levels correlate with the clinical and radiological manifestations of the disease. Sixty-six patients suffering from primary knee OA with effusion (26 males and 40 females) were studied. Twenty individuals (six males and 14 females) with recent traumatic knee effusion matched for age and sex were chosen to serve as a control group. All subjects had thorough clinical and radiological (X-ray and MRI) evaluation. Aggrecan and COMP in serum and synovial fluid were measured by ELISA. Serum and synovial fluid aggrecan and COMP levels were significantly higher than the control. Serum and synovial fluid aggrecan and COMP levels were positively correlated with age, body mass index, disease duration, plain X-ray and MRI scores. In OA, serum and synovial fluid aggrecan and COMP levels are elevated and represent useful markers in the diagnosis. Moreover, these elevated levels positively correlated with radiological joint damage but not with clinical disease parameters. These markers have the potential to be used for monitoring articular cartilage destruction and response to different therapeutic modalities.

Location specific radiographic joint space width for osteoarthritis progression

OBJECTIVE

To establish the performance of location specific computer measures of radiographic joint space width (JSW) compared to measurements of minimum joint space width (mJSW) for the assessment of medial compartment knee osteoarthritis (OA). The study also investigated the most disease-responsive location for measuring medial compartment JSW.

METHODS

Serial bilateral Posterior Anterior (PA) conventional radiographs acquired with a fixed flexion protocol were obtained 36 months apart in 118 persons with knee OA participating in the Health, Aging and Body Composition (Health ABC) Study. Measurements of medial compartment mJSW and JSW at seven fixed locations were facilitated by the use of semi-automated software that delineated the femoral and tibial margins of the joint. A human reader operated custom software to verify and correct the software-drawn margins where necessary. Paired images were displayed with the reader blinded to the chronological order. The amount of joint space narrowing was measured and the standardized response mean (SRM) was used as a metric to quantify performance.

RESULTS

For all subjects, the mJSW SRM value was 0.42 while, for the most responsive location specific measure of JSW, it was SRM=0.46. For subjects with a Kellgren-Lawrence (KL) score less than or equal to 1, mJSW (SRM=0.40) was more responsive than the new measures (Maximum SRM=0.30). For KL=2or3, SRM=0.49 for mJSW, and SRM=0.74 for the most responsive location specific measure of JSW. Improved responsiveness was observed in the more central portion of the joint on the more diseased knees.

CONCLUSIONS

Location specific computer measures of JSW are feasible and potentially provide a superior method to assess radiographic OA for more diseased subjects. This new measure has the potential to improve the power of clinical studies that use a fixed flexion protocol.

Comparison of quantitative imaging of cartilage for osteoarthritis: T2, T1rho, dGEMRIC and contrast-enhanced computed tomography

Evaluation of glycosaminoglycan (GAG) concentration in articular cartilage is of particular interest to the study of degenerative joint diseases such as osteoarthritis (OA). Noninvasive imaging techniques such as magnetic resonance imaging (MRI) and computed tomography (CT) have demonstrated the potential to assess biochemical markers of cartilage integrity such as GAG content; however, many imaging techniques are available and the optimization of particular techniques in the diagnosis of joint disease remains an active area of research. In order to highlight the differences between these various approaches, this work compares MRI (T1, T2 and T1rho) and contrast-enhanced CT in human articular cartilage, in both the presence and absence of gadolinium-based contrast agent. Pre- and postcontrast T2 values were found to be similar on a regional level and correlated with each other. As expected, T1 values were shortened significantly on both a global and a spatial basis in the presence of gadolinium (Gd); similar results were found for T1rho. T2 values were found to correlate mildly with postcontrast T1, T1(Gd) and with precontrast T1rho values. In addition, contrast-enhanced CT values correlated with both precontrast T1rho and T1(Gd) more strongly than with precontrast T2. Finally, T1(Gd) and precontrast T1rho were found to be moderately correlated with CT data. However, T1(Gd) and precontrast T1rho were found to be almost completely uncorrelated. Together, these results indicate that T1rho, T2 and contrast-enhanced techniques may provide complementary information about the molecular environment in cartilage during the evolution of OA.

Use of routine clinical multimodality imaging in a rabbit model of osteoarthritis--part I

OBJECTIVE

To evaluate in vivo the evolution of osteoarthritis (OA) lesions temporally in a rabbit model of OA with clinically available imaging modalities: computed radiography (CR), helical single-slice computed tomography (CT), and 1.5 tesla (T) magnetic resonance imaging (MRI).

METHODS

Imaging was performed on knees of anesthetized rabbits [10 anterior cruciate ligament transection (ACLT) and contralateral sham joints and six control rabbits] at baseline and at intervals up to 12 weeks post-surgery. Osteophytosis, subchondral bone sclerosis, bone marrow lesions (BMLs), femoropatellar effusion and articular cartilage were assessed.

RESULTS

CT had the highest sensitivity (90%) and specificity (91%) to detect osteophytes. A significant increase in total joint osteophyte score occurred at all time-points post-operatively in the ACLT group alone. BMLs were identified and occurred most commonly in the lateral femoral condyle of the ACLT joints and were not identified in the tibia. A significant increase in joint effusion was present in the ACLT joints until 8 weeks after surgery. Bone sclerosis or cartilage defects were not reliably assessed with the selected imaging modalities.

CONCLUSION

Combined, clinically available CT and 1.5 T MRI allowed the assessment of most of the characteristic lesions of OA and at early time-points in the development of the disease. However, the selected 1.5 T MRI sequences and acquisition times did not permit the detection of cartilage lesions in this rabbit OA model.

The acutely ACL injured knee assessed by MRI: changes in joint fluid, bone marrow lesions, and cartilage during the first year

OBJECTIVES

To investigate changes in the knee during the first year after acute rupture of the anterior cruciate ligament (ACL) of volumes of joint fluid (JF), bone marrow lesions (BMLs), and cartilage volume (VC), and cartilage thickness (ThCcAB) and cartilage surface area (AC). To identify factors associated with these changes.

METHODS

Fifty-eight subjects (mean age 26 years, 16 women) with an ACL rupture to a previously un-injured knee were followed prospectively using a 1.5T MR imager at baseline (within 5 weeks from injury), 3 months, 6 months, and 1 year. Thirty-four subjects were treated with ACL reconstruction followed by a structured rehabilitation program and 24 subjects were treated with structured rehabilitation only. Morphometric data were acquired from computer-assisted segmentation of MR images. Morphometric cartilage change was reported as mean change divided by the standard deviation of change (standard response mean, SRM).

RESULTS

JF and BML volumes gradually decreased over the first year, although BML persisted in 62% of the knees after 1 year. One year after the ACL injury, a reduction of VC, AC and ThCcAB (SRM -0.440 or greater) was found in the trochlea femur (TrF), while an increase of VC and ThCcAB was found in the central medial femur (cMF) (SRM greater than 0.477). ACL reconstruction was directly and significantly related to increased JF volume at 3 and 6 months (P<0.001), BML volume at 6 months (P=0.031), VC and ThCcAB in cMF (P<0.002) and decreased cartilage area in TrF (P=0.010) at 12 months.

CONCLUSION

Following an acute ACL tear, cMF and TrF showed the greatest consistent changes of cartilage morphometry. An ACL reconstruction performed within a mean of 6 weeks from injury was associated with increased ThCcAB and VC in cMF and decreased AC in TrF, compared to knees treated without reconstruction. This may suggest a delayed structural restitution in ACL reconstructed knees.

Correlation between arthroscopic and histopathological grading systems of articular cartilage lesions in knee osteoarthritis

PURPOSE

Arthroscopic and particularly histopathological assessments have been used to evaluate alterations of knee cartilage in osteoarthritis (OA). The aim of this study was to examine the correlation between an arthroscopic method to grade the severity of chondropathies and the histological/histochemical grading system (HHGS) applied to the corresponding articular cartilage areas in knee OA.

METHODS

The articular cartilage surface was examined by chondroscopy using the Beguin and Locker severity criteria, analysing the lesions in 72 chondroscopic areas. Afterwards, samples were obtained by dividing the cartilage surface of the medial tibiofemoral compartment of three OA knee joints into equal squares and they were evaluated histologically using the HHGS. The correlation between both grading methods was assessed using the weighted Kappa coefficient (K(w)).

RESULTS

The results obtained with both scores showed good agreement (K(w): mean+/-standard deviation, 0.619+/-0.071). While the average HHGS scores of the chondral samples showed a better agreement with arthroscopic grades 0, I and II, the arthroscopic evaluation has a tendency to overestimate chondral lesions for histological grades III and IV. The intra- and inter-observer reliability of the HHGS evaluation of chondral lesions was excellent (Intraclass Correlation Coefficient: 0.909 and 0.941, respectively).

CONCLUSION

In this study, we found a good quantitative correlation between established arthroscopic severity and histopathological scoring systems, particularly in less advanced lesions. Our results suggest that the arthroscopic method is a valuable tool in clinical research to score chondropathies in the medial femorotibial compartment of the OA knee, although some limitations should not be overlooked.

Minimum joint space width and tibial cartilage morphology in the knees of healthy individuals: a cross-sectional study

BACKGROUND

The clinical use of minimum joint space width (mJSW) and cartilage volume and thickness has been limited to the longitudinal measurement of disease progression (i.e. change over time) rather than the diagnosis of OA in which values are compared to a standard. This is primarily due to lack of establishment of normative values of joint space width and cartilage morphometry as has been done with bone density values in diagnosing osteoporosis. Thus, the purpose of this pilot study is to estimate reference values of medial joint space width and cartilage morphometry in healthy individuals of all ages using standard radiography and peripheral magnetic resonance imaging.

DESIGN

For this cross-sectional study, healthy volunteers underwent a fixed-flexion knee X-ray and a peripheral MR (pMR) scan of the same knee using a 1T machine (ONI OrthOne, Wilmington, MA). Radiographs were digitized and analyzed for medial mJSW using an automated algorithm. Only knees scoring <or=1 on the Kellgren-Lawrence scale (no radiographic evidence of knee OA) were included in the analyses. All 3D SPGRE fat-sat sagittal pMR scans were analyzed for medial tibial cartilage morphometry using a proprietary software program (Chondrometrics GmbH).

RESULTS

Of 119 healthy participants, 73 were female and 47 were male; mean (SD) age 38.2 (13.2) years, mean BMI 25.0 (4.4) kg/m2. Minimum JSW values were calculated for each sex and decade of life. Analyses revealed mJSW did not significantly decrease with increasing decade (p > 0.05) in either sex. Females had a mean (SD) medial mJSW of 4.8 (0.7) mm compared to males with corresponding larger value of 5.7 (0.8) mm. Cartilage morphometry results showed similar trends with mean (SD) tibial cartilage volume and thickness in females of 1.50 (0.19) microL/mm2 and 1.45 (0.19) mm, respectively, and 1.77 (0.24) microL/mm2 and 1.71 (0.24) mm, respectively, in males.

CONCLUSION

These data suggest that medial mJSW values do not decrease with aging in healthy individuals but remain fairly constant throughout the lifespan with "healthy" values of 4.8 mm for females and 5.7 mm for males. Similar trends were seen for cartilage morphology. Results suggest there may be no need to differentiate a t-score and a z-score in OA diagnosis because cartilage thickness and JSW remain constant throughout life in the absence of OA.

Reduction of truncation artifacts in rapid 3D articular cartilage imaging

PURPOSE

To reduce Gibbs ringing artifact in three-dimensional (3D) articular knee cartilage imaging with linear prediction (LP).

MATERIALS AND METHODS

A reconstruction method using LP in 3D was applied to truncated data sets of six healthy knees. The technique first linearizes the data before applying the prediction algorithm. Three radiologists blindly reviewed and ranked images of the full, truncated, and predicted data sets. Statistical analysis of the radiologists' reviews was performed for image quality, clinical acceptability of the images, and equivalence with the gold standard.

RESULTS

LP applied to 3D knee cartilage imaging allows for 40% decreased scan time while providing image quality with statistical equivalence to a full data set.

CONCLUSION

3D spoiled gradient echo imaging (SPGR) knee cartilage imaging requires significant scan time. This 40% reduction in scan time will allow such scans to be more feasible without sacrificing clinical acceptability.

Validity of the sonographic longitudinal sagittal image for assessment of the cartilage thickness in the knee osteoarthritis

We compared the validity of the sonographic longitudinal sagittal image with the suprapatellar transverse axial image for assessment of thickness of femoral cartilage in osteoarthritis (OA) patients. Fifty-one patients with knee OA were enrolled in this study. Cartilage thicknesses of medial and lateral femoral condyles were measured with longitudinal sagittal and suprapatellar transverse axial image using sonography. Fat-suppressed 3D spoiled gradient-echo magnetic resonance imaging (MRI) was also used to get the reference value. The joint space width (JSW) and Kellgren and Lawrence (K-L) grade were measured in weight-bearing anteroposterior knee radiograph. The kappa and intraclass correlation coefficient (ICC) were used to determine inter- and intra-observer agreement of the ultrasound sonography (US) measurements. In medial femoral condyle, the opportunity to obtain cartilage thickness was increased significantly using the longitudinal US scan as compared with tansverse scan (48 cases vs. 36 cases, p < 0.05). There was a good correlation between longitudinal US scan and MRI in the maximum and minimum cartilage thicknesses of medial condyle (r = 0.568; r = 0.844, respectively, p < 0.01). However, there was no correlation between suprapatellar transverse US scan and MRI in medial condyle. In lateral condyle, both US scans showed good correlations with MRI. In Bland-Altman analysis, longitudinal US scan showed good agreement with MRI except in the minimal cartilage thickness of lateral condyle. There was high overall intra- and inter-observer agreement in US scan. US scan in the longitudinal plane is a more feasible method than suprapatellar transverse scan for measuring cartilage thickness of medial femoral condyle in knee OA patient.

Osteophytosis, subchondral bone sclerosis, joint effusion and soft tissue thickening in canine experimental stifle osteoarthritis: comparison between 1.5 T magnetic resonance imaging and computed radiography

OBJECTIVE

To compare use of 1.5 T magnetic resonance imaging (MRI) and computed radiography (CR) for morphologic and temporal evaluation of osteophytosis, subchondral sclerosis, joint effusion, and synovial thickening in experimentally induced canine stifle osteoarthritis (OA).

STUDY DESIGN

Prospective study.

ANIMALS

Dogs (n=8).

METHODS

CR (mediolateral and caudocranial projections) and MRI (dorsal 3D T1-weighted gradient echo, sagittal 3D SPGR and T2-weighted fast spin echo with fat saturation) were performed at baseline (n=8) and at week 4 (n=5), week 8 (n=8), and week 26 (n=5) after cranial cruciate ligament transection. Osteophytosis, subchondral bone sclerosis, and joint effusion were scored on CR and MRI, and synovial thickening on MRI.

RESULTS

MRI was more sensitive than CR for detection of osteophytosis and could better discriminate joint effusion from soft tissue thickening, although scores for these variables strongly correlated between modalities (rho=0.94 [osteophytosis] and 0.80 [effusion]; P<.001). Scores for subchondral bone sclerosis also correlated (rho=0.54, P<.004), although this variable may have been over interpreted on CR. Joint effusion and synovial thickening peaked at week 8, before partially regressing at week 26. Conversely, osteophytosis and sclerosis progressed semi-linearly over 26 weeks.

CONCLUSION

MRI is more sensitive than radiography in assessing onset and progression of osteophytosis in canine experimental stifle OA and provides enhanced discrimination between joint effusion and synovial thickening.

CLINICAL RELEVANCE

MRI is as a more powerful imaging modality that should be increasingly used in animals to assess the joint related effects of disease-modifying OA drugs.

Allometric relationships between knee cartilage volume, thickness, surface area and body dimensions

OBJECTIVE

To determine if anthropometric factors obtainable on routine examination can be used to estimate premorbid knee total subchondral bone area (tAB), cartilage surface area (AC), cartilage thickness (ThC), and cartilage volume (VC).

METHOD

Young individuals (21-39 years old) without history of knee joint pain, injury or disease were studied. Magnetic resonance imaging of the right knee was used to determine tAB, AC, ThC and VC for knee cartilage. Multilinear regression and curve fitting by variance minimization were used to model the data.

RESULTS

VC and AC closely depended on tAB(1.5) in both men and women. This relationship subsumed all dependency on sex, height, weight and body mass index. In females, VC depended on height cubed and tAB on height squared. The relationship was much weaker in males. ThC was poorly related to tAB and VC. Confidence limits for VC standardized to tAB(1.5) were narrower than standardization to tAB or height.

CONCLUSION

The absence of a tight relationship of VC and tAB with height in males suggests that the factors stimulating bone and cartilage growth may be different between sexes. The high correlation between tAB and VC across both sexes suggests, however, that (opposite to measures from routine clinical examination) tAB(1.5) can provide individual reference values for VC, against which changes with age and disease can be estimated with high confidence.

Two year longitudinal change and test-retest-precision of knee cartilage morphology in a pilot study for the osteoarthritis initiative

OBJECTIVE

Fast low angle shot (FLASH) and double echo steady state (DESS) magnetic resonance imaging (MRI) acquisitions were recently cross-calibrated for quantification of cartilage morphology at 3T. In this pilot study for the osteoarthritis (OA) initiative we compare their test-retest-precision and sensitivity to longitudinal change.

METHOD

Nine participants with mild to moderate clinical OA were imaged twice each at baseline, year 1 (Y1) and year 2 (Y2). Coronal 1.5mm FLASH and sagittal 0.7mm DESS sequences were acquired; 1.5mm coronal multiplanar reformats (MPR) were obtained from the DESS. Patellar, femoral and tibial cartilage plates were quantified in a paired fashion, with blinding to time point.

RESULTS

In the weight-bearing femorotibial joint, average precision errors across plates were 1.8% for FLASH, 2.6% for DESS, and 3.0% for MPR-DESS. Volume loss at Y1 was not significant; at Y2 the average change across the femorotibial cartilage plates was -1.7% for FLASH, -2.8% for DESS, and -0.3% for MPR-DESS. Volume change in the lateral tibia (-5.5%; P<0.03), and in the medial (-2.9%; P<0.04) and lateral femorotibial compartments (-3.8%; P<0.03) were significant for DESS.

CONCLUSIONS

FLASH, DESS and MPR-DESS all displayed adequate test-retest precision. Although the comparison between protocols is limited by the small number of participants and by the relatively small longitudinal change in cartilage morphology in this pilot study, the data suggest that significant change can be detected with MRI in a small sample of OA subjects over 2 years.

Computer-aided grading and quantification of hip osteoarthritis severity employing shape descriptors of radiographic hip joint space

A computer-based system was designed for the grading and quantification of hip osteoarthritis (OA) severity. Employing an active-contours segmentation model, 64 hip joint space (HJS) images (18 normal, 46 osteoarthritic) were obtained from the digitized radiographs of 32 unilateral and bilateral OA-patients. Shape features, generated from the HJS-images, and a hierarchical decision tree structure was used for the grading of OA. A shape features based regression model quantified the OA-severity. The system accomplished high accuracies in characterizing hips as "Normal" (100%), of "mild/moderate"-OA (93.8%) or "severe"-OA (96.7%). OA-severity values, as expressed by HJS-narrowing, correlated highly (r=0.9,p<0.001) with the values predicted by the regression model. The system may contribute to OA-patient management.

Clusters of biochemical markers are associated with radiographic subtypes of osteoarthritis (OA) in subject with familial OA at multiple sites. The GARP study

OBJECTIVE

To assess the relationship of biochemical markers and radiographic signs of osteoarthritis (ROA) in the subjects with symptomatic osteoarthritis (OA) at multiple sites of the Genetics osteoARthritis and Progression (GARP) study.

METHODS

We have measured eight biochemical markers, representing tissue turnover of cartilage, bone, synovium, and inflammation. ROA was assessed in the knees, hips, hands, vertebral facet joints and spinal disc degeneration (DD) by using the Kellgren score. A proportionate score was subsequently made for each joint location based on the number of joints with ROA. Principal component and linear mixed model analyses were applied to analyze the data.

RESULTS

Three different clusters of markers were identified that may reflect different pathophysiological processes of OA. The first component appeared to be reflected by structural markers of cartilage and bone turnover and associated especially in subjects with hip ROA. The second component was reflected by a marker of inflammation and was associated with knee ROA, high Western Ontario and McMaster Universities (WOMAC) scores and body mass index (BMI). The third component included markers of cartilage turnover and was associated with ROA at hands, spine as well as age. High familial aggregation was observed for serum cartilage oligomeric matrix protein (S-COMP) (70%) and serum N-propeptide of collagen type IIA (S-PIIANP) (62%).

CONCLUSION

Using a large well-characterized study and eight biochemical markers, we were able to observe three components that may reflect different molecular mechanisms (bone, cartilage, synovium turnover and inflammation). Our data suggested that these components contribute differently to ROA at different joint sites.

Volumetric cartilage measurements of porcine knee at 1.5-T and 3.0-T MR imaging: evaluation of precision and accuracy

PURPOSE

To compare the precision and accuracy of 3.0-T and 1.5-T magnetic resonance (MR) imaging in the quantification of cartilage volume by using direct volumetric measurements as a reference standard.

MATERIALS AND METHODS

The local animal experimentation committee did not require its approval for this study. Porcine knees were obtained from an abattoir. These specimens were used to optimize imaging parameters regarding effective signal-to-noise ratio (SNRE) and contrast-to-noise ratio (CNRE) for a fat-saturated spoiled gradient-recalled acquisition in the steady state (SPGR) sequence, a water excitation SPGR sequence, and a fast spin-echo sequence at 3.0 T and a fat-saturated SPGR sequence at 1.5 T. By using the optimized sequences, 18 specimens were imaged in less than 6 minutes per sequence. A fivefold repetition of measurements of four specimens was performed for precision analysis. Cartilage was segmented by using semiautomatic software to calculate the volume. After imaging, the cartilage was scraped off and the volume was measured directly by using a saline-displacement method to calculate accuracy. Precision and accuracy errors were calculated as the root-mean-squares of the single errors per specimen.

RESULTS

SNRE and CNRE values, respectively, were highest for the water excitation sequence at 3.0 T (1.81 sec(-1/2) and 1.27 sec(-1/2)), followed by the fat-saturated SPGR sequence (1.52 sec(-1/2) and 1.07 sec(-1/2)). The fast spin-echo sequence and the fat-saturated SPGR sequence at 1.5 T had lower SNR(E) (1.27 sec(-1/2) and 0.59 sec(-1/2), respectively). Accuracy error for MR-based volume calculation at the femur was 5.0%, 3.0%, 21%, and 16% for the water excitation, fat-saturated SPGR, and fast spin-echo sequences at 3.0 T and the fat-saturated SPGR sequence at 1.5 T, respectively.

CONCLUSION

MR imaging at 3.0 T was shown in our study to better quantify cartilage volume. SNRE and CNRE were substantially improved, resulting in significantly higher accuracy in determining cartilage volume.

Sodium and T1rho MRI for molecular and diagnostic imaging of articular cartilage

In this article, both sodium magnetic resonance (MR) and T1rho relaxation mapping aimed at measuring molecular changes in cartilage for the diagnostic imaging of osteoarthritis are reviewed. First, an introduction to structure of cartilage, its degeneration in osteoarthritis (OA) and an outline of diagnostic imaging methods in quantifying molecular changes and early diagnostic aspects of cartilage degeneration are described. The sodium MRI section begins with a brief overview of the theory of sodium NMR of biological tissues and is followed by a section on multiple quantum filters that can be used to quantify both bi-exponential relaxation and residual quadrupolar interaction. Specifically, (i) the rationale behind the use of sodium MRI in quantifying proteoglycan (PG) changes, (ii) validation studies using biochemical assays, (iii) studies on human OA specimens, (iv) results on animal models and (v) clinical imaging protocols are reviewed. Results demonstrating the feasibility of quantifying PG in OA patients and comparison with that in healthy subjects are also presented. The section concludes with the discussion of advantages and potential issues with sodium MRI and the impact of new technological advancements (e.g. ultra-high field scanners and parallel imaging methods). In the theory section on T1rho, a brief description of (i) principles of measuring T1rho relaxation, (ii) pulse sequences for computing T1rho relaxation maps, (iii) issues regarding radio frequency power deposition, (iv) mechanisms that contribute to T1rho in biological tissues and (v) effects of exchange and dipolar interaction on T1rho dispersion are discussed. Correlation of T1rho relaxation rate with macromolecular content and biomechanical properties in cartilage specimens subjected to trypsin and cytokine-induced glycosaminoglycan depletion and validation against biochemical assay and histopathology are presented. Experimental T1rho data from osteoarthritic specimens, animal models, healthy human subjects and as well from osteoarthritic patients are provided. The current status of T1rho relaxation mapping of cartilage and future directions is also discussed.

Quantitative MRI of cartilage and bone: degenerative changes in osteoarthritis

Magnetic resonance imaging (MRI) and quantitative image analysis technology has recently started to generate a great wealth of quantitative information on articular cartilage and bone physiology, pathophysiology and degenerative changes in osteoarthritis. This paper reviews semiquantitative scoring of changes of articular tissues (e.g. WORMS = whole-organ MRI scoring or KOSS = knee osteoarthritis scoring system), quantification of cartilage morphology (e.g. volume and thickness), quantitative measurements of cartilage composition (e.g. T2, T1rho, T1Gd = dGEMRIC index) and quantitative measurement of bone structure (e.g. app. BV/TV, app. TbTh, app. Tb.N, app. Tb.Sp) in osteoarthritis. For each of these fields we describe the hardware and MRI sequences available, the image analysis systems and techniques used to derive semiquantitative and quantitative parameters, the technical accuracy and precision of the measurements reported to date and current results from cross-sectional and longitudinal studies in osteoarthritis. Moreover, the paper summarizes studies that have compared MRI-based measurements with radiography and discusses future perspectives of quantitative MRI in osteoarthritis. In summary, the above methodologies show great promise for elucidating the pathophysiology of various tissues and identifying risk factors of osteoarthritis, for developing structure modifying drugs (DMOADs) and for combating osteoarthritis with new and better therapy.

Proposal for a nomenclature for magnetic resonance imaging based measures of articular cartilage in osteoarthritis

OBJECTIVE

Magnetic resonance imaging (MRI) of articular cartilage has evolved to be an important tool in research on cartilage (patho)physiology and osteoarthritis (OA). MRI provides a wealth of novel and quantitative information, but there exists no commonly accepted terminology for reporting these metrics. The objective of this initiative was to propose a nomenclature for definitions and names to be used in scientific communications and to give recommendations as to which minimal methodological information should be provided when reporting MRI-based measures of articular cartilage in OA.

METHODS

An international group of experts with direct experience in MRI measurement of cartilage morphology or composition reviewed the existing literature. Through an iterative process that included a meeting with a larger group of scientists and clinicians (December 2nd, 2004, Chicago, IL, USA), they discussed, refined, and proposed a nomenclature for MRI-based measures of articular cartilage in OA.

RESULTS

The group proposes a nomenclature that describes: (1) the anatomical location and (2) the structural feature being measured, each name consisting of a metric variable combined with a tissue label. In addition, the group recommends minimal methodological information that should be described.

CONCLUSIONS

Utilization of this nomenclature should facilitate communication within the scientific community. Further, the uniform adoption of comprehensive nomenclature to describe quantitative MRI- features of articular cartilage should strengthen epidemiological, clinical, and pharmacological studies in OA.

Magnetic resonance imaging (MRI) of articular cartilage in knee osteoarthritis (OA): morphological assessment

OBJECTIVE

Magnetic resonance imaging (MRI) is a three-dimensional imaging technique with unparalleled ability to evaluate articular cartilage. This report reviews the current status of morphological assessment of cartilage with quantitative MRI (qMRI), and its relevance for identifying disease status, and monitoring progression and treatment response in knee osteoarthritis (OA).

METHOD

An international panel of experts in MRI of knee OA, with direct experience in the analysis of cartilage morphology with qMRI, reviewed the existing published and unpublished data on the subject, and debated the findings at the OMERACT-OARSI Workshop on Imaging technologies (December 2002, Bethesda, MA) with scientists and clinicians from academia, the pharmaceutical industry and the regulatory agencies. This report reviews (1) MRI pulse sequence considerations for morphological analysis of articular cartilage; (2) techniques for segmenting cartilage; (3) semi-quantitative scoring of cartilage status; and (4) technical validity (accuracy), precision (reproducibility) and sensitivity to change of quantitative measures of cartilage morphology.

RESULTS

Semi-quantitative scores of cartilage status have been shown to display adequate reliability, specificity and sensitivity, and to detect lesion progression at reasonable observation periods (1-2 years). Quantitative assessment of cartilage morphology (qMRI), with fat-suppressed gradient echo sequences, and appropriate image analysis techniques, displays high accuracy and adequate precision (e.g., root-mean-square standard deviation medial tibia=61 microl) for cross-sectional and longitudinal studies in OA patients. Longitudinal studies suggest that changes of cartilage volume of the order of -4% to -6% occur per annum in OA in most knee compartments (e.g., -90 microl in medial tibia). Annual changes in cartilage volume exceed the precision errors and appear to be associated with clinical symptoms as well as with time to knee arthroplasty.

CONCLUSIONS

MRI provides reliable and quantitative data on cartilage status throughout most compartments of the knee, with robust acquisition protocols for multi-center trials now being available. MRI of cartilage has tremendous potential for large scale epidemiological studies of OA progression, and for clinical trials of treatment response to structure modifying OA drugs.

Quantitative assessment of hip osteoarthritis based on image texture analysis

A non-invasive method was developed to investigate the potential capacity of digital image texture analysis in evaluating the severity of hip osteoarthritis (OA) and in monitoring its progression. 19 textural features evaluating patterns of pixel intensity fluctuations were extracted from 64 images of radiographic hip joint spaces (HJS), corresponding to 32 patients with verified unilateral or bilateral OA. Images were enhanced employing custom developed software for the delineation of the articular margins on digitized pelvic radiographs. The severity of OA for each patient was assessed by expert orthopaedists employing the Kellgren and Lawrence (KL) scale. Additionally, an index expressing HJS-narrowing was computed considering patients from the unilateral OA-group. A textural feature that quantified pixel distribution non-uniformity (grey level non-uniformity, GLNU) demonstrated the strongest correlation with the HJS-narrowing index among all extracted features and utilized in further analysis. Classification rules employing GLNU feature were introduced to characterize a hip as normal or osteoarthritic and to assign it to one of three severity categories, formed in accordance with the KL scale. Application of the proposed rules resulted in relatively high classification accuracies in characterizing a hip as normal or osteoarthritic (90.6%) and in assigning it to the correct KL scale category (88.9%). Furthermore, the strong correlation between the HJS-narrowing index and the pathological GLNU (r = -0.9, p<0.001) was utilized to provide percentages quantifying hip OA-severity. Texture analysis may contribute in the quantitative assessment of OA-severity, in the monitoring of OA-progression and in the evaluation of a chondroprotective therapy.

Osteoarthritis of the knee: comparison of MR imaging findings with radiographic severity measurements and pain in middle-aged women

PURPOSE

To prospectively compare magnetic resonance (MR) imaging-defined abnormalities of osteoarthritis (OA) of the knee with radiographic severity measurements of OA of the knee and self-reported pain.

MATERIALS AND METHODS

This study was approved by the institutional review board of University of Michigan. Informed consent was obtained for this HIPAA-compliant study. Knee MR imaging was performed in 117 women (mean age, 46 years; range, 32-56 years) from a community-based arthritis study (n = 1053) with 30 women in each of four categories: (a) no pain and no OA of the knee, (b) no pain and OA of the knee, (c) pain and no OA of the knee, and (d) pain and OA of the knee. OA of the knee was defined from radiographs. Two hundred thirty-two eligible knees had Kellgren-Lawrence scores for OA of the knee as follows: grade 0, 115 (49.6%); grade 1, 33 (14.2%); grade 2, 66 (28.4%); grade 3, 17 (7.3%); and grade 4, one (0.4%). MR images were assessed for location and severity of defects of cartilage, bone marrow edema (BME), osteophytes, subchondral cysts, sclerosis, meniscal and/or ligamentous tears, joint effusion, synovial cysts, and synovitis. MR imaging findings were compared with radiographic severity of OA of the knee (Kellgren-Lawrence scale) and self-reported pain with analysis of variance, t tests, and contingency table analyses.

RESULTS

Defects of cartilage (higher than grade IIA) were found in 75% of knees; BME was found in 57% of knees (<1 cm, 41%; >1 cm, 16%). Large BME lesions were common in the pain and OA of the knee group (P = .001); this group was significantly more likely to have defects of cartilage (P = .001); meniscal tears (P = .001); and osteophytes, subchondral cysts, sclerosis, joint effusion, and synovitis (P < .001). Defects of cartilage, osteophytes, sclerosis, meniscal or ligamentous tears, joint effusion, and synovitis were strongly related to increasing Kellgren-Lawrence grade (P < .001).

CONCLUSION

In middle-aged women, there were significant associations between pain, radiographic severity of OA of the knee, and seven MR imaging-identified parameters.

The relationships between bone mineral density in the spine, hip, distal femur and proximal tibia and medial minimum joint space width in the knees of healthy females

OBJECTIVE

To investigate the relationships between bone mineral density (BMD) in the hip, spine, distal femur and proximal tibia and minimum joint space width (mJSW) in the knees of healthy women.

METHODS

Women 22-68 years old without a history of knee pain, bone or joint disease or injury underwent a single, fixed-flexion knee X-ray. Radiographs were graded according to the Kellgren-Lawrence scale and analyzed for mJSW using a computer algorithm. Dual X-ray absorptiometry scans of the spine, hip, distal femur and proximal tibia were also acquired for each participant. Femur and tibia scans were acquired and analyzed using a modified version of the lumbar spine software.

RESULTS

Forty-five females, mean [standard deviation (SD)] age and body mass index (BMI) of 40.1 (13.9) years and 24.6 (4.5)kg/m(2), respectively, participated. The mean (SD) mJSW was 4.64 (0.68)mm. Linear regression analyses controlling for age and BMI revealed that BMD in the femoral trochanter and the central two regions of the tibia (T2 and T3) was significantly related to mJSW in the knee. A backwards regression analysis performed to determine which region of interest is most significantly related to mJSW revealed that femoral trochanter BMD (beta-value=0.416) is the most significant.

CONCLUSIONS

In contrast to the suggestion that BMD is negatively correlated with mJSW in the knees of osteoarthritic individuals, these results suggest that increasing BMD in the femoral trochanter and tibia is significantly associated with increasing mJSW in healthy females. Further investigation of this relationship is warranted.

Urinary CTX-II levels are associated with radiographic subtypes of osteoarthritis in hip, knee, hand, and facet joints in subject with familial osteoarthritis at multiple sites: the GARP study

OBJECTIVE

To assess the relation between the urinary concentrations of type II collagen C-telopeptide (UCTX-II) and radiographic signs of osteoarthritis (ROA) in the GARP (Genetics, Arthrosis and Progression) study.

METHODS

UCTX-II levels were measured in GARP study participants, who are sibling pairs predominantly with symptomatic osteoarthritis at multiple sites. Kellgren and Lawrence scores were used to assess ROA in the knees, hips, hands, and vertebral facet joints, and spinal disc degeneration. A proportionate score was made for each joint location, based on the number of joints with ROA. The sum total ROA score represents a measure of cartilage abnormalities within each patient. By using linear mixed models the total ROA score and the joint site specific ROA scores were correlated with the UCTX-II level.

RESULTS

In 302 subjects the mean (SD) and median (range) for UCTX-II were 265 (168) and 219 (1346) ng/mmol creatine, respectively. There was a significant association between the total ROA score and UCTX-II levels. Subsequent multivariate analysis showed that the joint site specific ROA score at all joint sites, except for spinal disc degeneration, contributed independently to this association.

CONCLUSIONS

The total ROA score of GARP patients, representing cartilage abnormalities at the most prevalent ROA joint locations, showed an excellent correlation with UCTX-II levels. The specific ROA scores at the hip, hand, facet, and knee joints additively and independently explained this association. Even in patients with osteoarthritis at multiple sites, UCTX-II may be a sensitive quantitative marker of ROA.

Quantitative outcome measures of cartilage repair in patients treated by tissue engineering

Reliable and reproducible outcome measures are essential to assess the efficacy of competing and novel tissue-engineering techniques. The aim of this study was to compare traditional histological analyses with newly developed quantitative biochemical outcome measures for the repair of articular cartilage. The production of a new anti-peptide antibody and the development and validation of a novel method for the extraction and immunoassay of type I collagen are described. The assay was used, in conjunction with existing assays for type II collagen and proteoglycans, to measure levels of the matrix components in repair tissue biopsies obtained from patients treated with the new tissue-engineering therapy Hyalograft C. Frozen sections cut from the same biopsies were stained for proteoglycans, using safranin O, and immunohistochemical analysis was used to assess type I and II collagen staining. Although there was general agreement between the extent of staining and the amounts of the three matrix components, there was a large degree of overlap in biochemical content between biopsies classified histologically on the basis of low, moderate, or abundant staining. The results demonstrate that histological grading of matrix protein abundance to classify repair cartilage as hyaline or fibrocartilagenous is often misleading. In addition, we demonstrate for the first time the ability to measure collagen cross-links in repair tissue biopsies and show that it can be used as a surrogate marker for tissue maturity. Our new range of biochemical techniques provides a standardized method to assess the quality of both engineered cartilage produced in vitro and repair tissue biopsies obtained after in vivo implantation.

Quantitative cartilage volume measurement using MRI: comparison of different evaluation techniques

This study was aimed to investigate the accuracy and time saving of MRI Argus application in the assessment of cartilage volume in osteoarthritic knees. Twelve knees of patients suffering from osteoarthritis were scanned with a 1.5 T MRI using a 3D gradient echo sequence with selective water excitation. Cartilage volume of the tibial and patellar compartment was determined with a validated multiprocessing computer system (Octane Duo, Silicon Graphics, Mountain View, Calif., USA). The calculated cartilage volumes were compared to the results acquired by the Argus (Siemens Inc., Erlangen, Germany) application software using the MRI data sets. Compared to the multiprocessing computer system a time saving of at least 30 min for cartilage volume determination was achieved. The mean differences of Argus versus the multiprocessing computer system were 4.26+/-0.84 and 7.80+/-0.87% for the medial and lateral tibial plateau and 5.94+/-0.59% for the patella (no statistical significant difference; P>0.05). The applied Argus software can be used for fast and accurate determination of cartilage volume in the knee joint.

MR imaging of articular cartilage at 1.5T and 3.0T: comparison of SPGR and SSFP sequences

OBJECTIVE

To compare articular cartilage signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and thickness measurements on a 1.5 T and a 3.0 T magnetic resonance (MR) scanner using three-dimensional spoiled gradient recalled echo (3D-SPGR) and two 3D steady-state free precession (SSFP) sequences.

METHODS

Both knees of five volunteers were scanned at 1.5 T and at 3.0 T using a transmit-receive quadrature extremity coil. Each examination consisted of a sagittal 3D-SPGR sequence, a sagittal fat suppressed 3D-SSFP (FS-SSFP) sequence, and a sagittal Dixon 3D-SSFP sequence. For quantitative analysis, we compared cartilage SNR and CNR efficiencies, as well as average cartilage thickness measurements.

RESULTS

For 3D-SPGR, cartilage SNR efficiencies at 3.0 T increased compared to those at 1.5 T by a factor of 1.83 (range: 1.40-2.09). In comparison to 3D-SPGR, the SNR efficiency of FS-SSFP increased by a factor of 2.13 (range: 1.81-2.39) and for Dixon SSFP by a factor of 2.39 (range: 1.95-2.99). For 3D-SPGR, CNR efficiencies between cartilage and its surrounding tissue increased compared to those at 1.5 T by a factor of 2.12 (range: 1.75-2.47), for FS-SSFP by a factor 2.11 (range: 1.58-2.80) and for Dixon SSFP by a factor 2.39 (range 2.09-2.83). Average cartilage thicknesses of load bearing regions were not different at both field strengths or between sequences (P>0.05). Mean average cartilage thickness measured in all knees was 2.28 mm.

CONCLUSION

Articular cartilage imaging of the knee on a 3.0 T MR scanner shows increased SNR and CNR efficiencies compared to a 1.5 T scanner, where SSFP-based techniques show the highest increase in SNR and CNR efficiency. There was no difference between average cartilage thickness measurements performed at the 1.5 T and 3.0 T scanners or between the three different sequences.

Abnormalities identified in the knees of asymptomatic volunteers using peripheral magnetic resonance imaging

OBJECTIVE

To estimate the prevalence of bone and soft tissue abnormalities in asymptomatic knees using peripheral magnetic resonance imaging (pMRI) and to examine the relationship between these abnormalities and Kellgren-Lawrence (K-L) graded X-rays.

METHOD

Volunteers (20-68 years) with no history of knee pain, injury or bone or joint disease were recruited. Individuals underwent a single MRI scan and radiograph of their non-dominant knee. pMR images were acquired in sagittal plane using a 3-D gradient-echo protocol. Two radiologists graded the presence and severity of cartilage degeneration, osteophytosis, meniscal and ligamentous abnormalities, bone marrow edema and subchondral cysts. X-rays were acquired using a fixed-flexion technique and graded using the K-L scale.

RESULTS

Forty-four individuals, mean age (SD) 41.1 (14.2) years, participated. K-L grading of X-rays revealed 29 individuals were grade 0, 12 were grade 1 and 3 were grade 2. Five individuals showed evidence of cartilage lesions, the femoral trochlea, medial femur and patella being those regions most commonly affected. Twelve individuals (27.3%) showed evidence of osteophytosis, nine of whom did not show evidence on X-ray. Forty-three individuals showed evidence of at least one meniscal abnormality while 27 individuals (61.4%) had abnormalities in at least three of the four regions of the knee.

CONCLUSION

Our results suggest that osteophytes may be more prevalent in this population than radiographic data suggests due to the limitations of two-dimensional imaging. Meniscal degeneration or tears, a risk factor for knee osteoarthritis, are highly prevalent in asymptomatic individuals with the medial anterior and posterior horns being the most commonly affected regions.

Magnetic resonance imaging of peripheral joints in rheumatic diseases

The need for better methods than the conventional clinical, biochemical and radiographical examinations in the management of inflammatory joint diseases is evident, since these methods are not sensitive or specific to early pathologies and subtle changes. Magnetic resonance imaging (MRI) offers improved sensitivity to early inflammatory and destructive changes in peripheral joints in rheumatoid arthritis (RA) and, even though less well documented, in other inflammatory joint diseases. Good evidence is available that MRI bone erosions represent true bone abnormalities and are predictors of radiographical outcome in RA. Similarly, there is solid evidence for MRI synovitis representing true synovial inflammation and being of considerable practical, clinical and radiological significance in RA. Describing the encouraging current knowledge regarding MRI for diagnosis, monitoring and prognosis, this chapter discusses the potential for the use of MRI in the clinical management of patients with suspected and diagnosed inflammatory joint diseases, as well as research priorities and clinical situations where the use of MRI could be suggested.

MRI assessment of knee osteoarthritis: Knee Osteoarthritis Scoring System (KOSS)--inter-observer and intra-observer reproducibility of a compartment-based scoring system

OBJECTIVE

To develop a scoring system for quantifying osteoarthritic changes of the knee as identified by magnetic resonance (MR) imaging, and to determine its inter- and intra-observer reproducibility, in order to monitor medical therapy in research studies.

DESIGN AND PATIENTS

Two independent observers evaluated 25 consecutive MR examinations of the knee in patients with previously defined clinical symptoms and radiological signs of osteoarthritis. We acquired on a 1.5 T system: coronal and sagittal proton density- and T2-weighted dual spin echo (SE) images, sagittal three-dimensional T1-weighted gradient echo (GE) images with fat suppression, and axial dual turbo SE images with fat suppression. Images were scored for the presence of cartilaginous lesions, osteophytes, subchondral cysts, bone marrow edema, and for meniscal abnormalities. Presence and size of effusion, synovitis and Baker's cyst were recorded. All parameters were ranked on a previously defined, semiquantitative scale, reflecting increasing severity of findings. Kappa, weighted kappa and intraclass correlation coefficient (ICC) were used to determine inter- and intra-observer variability.

RESULTS

Inter-observer reproducibility was good (ICC value 0.77). Inter- and intra-observer reproducibility for individual parameters was good to very good (inter-observer ICC value 0.63-0.91; intra-observer ICC value 0.76-0.96).

CONCLUSION

The presented comprehensive MR scoring system for osteoarthritic changes of the knee has a good to very good inter-observer and intra-observer reproducibility. Thus the score form with its definitions can be used for standardized assessment of osteoarthritic changes to monitor medical therapy in research studies.

Short tau inversion recovery and proton density-weighted fat suppressed sequences for the evaluation of osteoarthritis of the knee with a 1.0 T dedicated extremity MRI: development of a time-efficient sequence protocol

Aim of this study was to develop a time-efficient sequence protocol for a 1.0 T dedicated MR system to be used for whole-organ scoring of osteoarthritis (OA). Thirty-four knees were examined using a protocol that included fat suppressed fast spin echo proton density weighted sequences (PDFS) in three planes plus a coronal STIR sequence. Two radiologists scored each knee by consensus for five OA features. In separate sessions, all knees were scored using three different combinations of sequences: (1) all four sequences (reference protocol, 16 min 31 s scanning time), (2) three PDFS sequences without STIR ("No STIR", 12 min 25 s scanning time) and (3) sagittal and axial PDFS sequences plus a coronal STIR sequence ("No PDFS", 11 min 49 s scanning time). Agreement of the readings using both subsets of sequences compared to the reference protocol was evaluated using weighted kappa statistics. kappa-coefficients showed good or excellent agreement for both sequence subsets in comparison to the reference protocol for all assessed features. kappa-coefficients for No PDFS/No STIR: bone marrow abnormalities (0.74/0.67), subarticular cysts (0.84/0.63), marginal osteophytes (0.77/0.71), menisci (0.75/0.79), tibial cartilage (0.71/0.78). Optimization of sequence protocols consisting of three sequences results in time savings and cost efficiency in imaging of knee OA without loss of information over a more time consuming protocol.

Use of novel interactive input devices for segmentation of articular cartilage from magnetic resonance images

OBJECTIVE

To study the effect of new interactive computer input devices on cartilage segmentation in terms of time, consistency between input devices, and precision in quantitative magnetic resonance imaging (qMRI).

DESIGN

We compared two new input devices, an interactive digitizing tablet and an interactive touch-sensitive screen, to a traditional mouse. Medial tibial and patellar cartilage of six healthy and six osteoarthritic knees were segmented using each input device. Cartilage volume, surface area and mean thickness were assessed using a validated algorithm and used to determine consistency and precision. Segmentation time was also measured.

RESULTS

Segmenting with an interactive touch-sensitive screen reduced segmentation time by 15% when compared to the traditional mouse but we found no significant difference in segmentation time between the interactive digitizing tablet and the traditional mouse. We found no difference in consistency or precision of cartilage volume, mean thickness or surface area between the three input devices tested.

CONCLUSIONS

We conclude that measurements of cartilage made using articular cartilage segmentation from MR images are independent of the input device chosen for user interaction.

Urinary type II collagen helical peptide (HELIX-II) as a new biochemical marker of cartilage degradation in patients with osteoarthritis and rheumatoid arthritis

OBJECTIVE

Type II collagen, which consists of a large helical domain and telopeptides at each end, is the most abundant protein of cartilage matrix. The aim of this study was to develop a biochemical marker reflecting the degradation of the helical region of type II collagen and to evaluate its clinical performance in patients with osteoarthritis (OA) and rheumatoid arthritis (RA).

METHODS

We developed a competitive polyclonal antibody-based enzyme-linked immunosorbent assay (ELISA) using the 622-632 peptide derived from the sequence of the alpha1 chain of human type II collagen (HELIX-II) as immunogen and standard. We measured urinary levels of HELIX-II peptide and C-terminal crosslinking telopeptide of type II collagen (CTX-II) in 90 patients with knee OA (73% women; mean +/- SD age 63.0 +/- 8.0 years, mean +/- SD disease duration 6.1 +/- 6.8 years), 89 patients with early RA (disease duration </=3 years) (79% women; mean +/- SD age 48.7 +/- 11.6 years), 25 patients with Paget's disease of bone (HELIX-II only), and 162 healthy controls. In RA patients, we investigated the relationships between baseline urinary HELIX-II and CTX-II levels and the progression of joint destruction as measured by the changes in the total Sharp score (average from 2 independent readers) over 1 year.

RESULTS

The intraassay and interassay variations of the HELIX-II ELISA were lower than 13% and 15%, respectively. The HELIX-II ELISA showed no significant cross-reactivity with human intact or denatured type II collagen, with the homologous peptides from human type I or type III collagens, or with HELIX-II peptides elongated (by 1 amino acid) or shortened (by 1 or 2 amino acids) at the C-terminal end, indicating that the HELIX-II ELISA recognized a neoepitope from the alpha1 chain of type II collagen. Median urinary HELIX-II levels were increased in patients with knee OA (by 56%; P < 0.0001) or early RA (by 123%; P < 0.0001) compared with those in age- and sex-matched healthy controls. Baseline urinary HELIX-II levels in the highest tertile were associated with an increased risk of radiographic progression in RA (increase in the total Sharp score >/=0.5 units/year), with an odds ratio (OR) of 5.9 (95% confidence interval [95% CI] 2.0-17.2) after adjustment for serum C-reactive protein (CRP) levels and baseline joint damage. Patients with increased levels of both urinary HELIX-II and CTX-II had the highest risk of progression (OR 17.5 [95% CI 3.1-99]).

CONCLUSION

The HELIX-II ELISA is specific for type II collagen degradation, has adequate technical performance, and can distinguish patients with knee OA or RA from healthy controls. Elevated HELIX-II levels are associated with increased risk of radiographic progression in RA independently of CRP levels, baseline joint damage, and urinary CTX-II levels. The HELIX-II ELISA should be useful for the clinical investigation of patients with arthritis and for identifying RA patients at higher risk of progression.

Correlation and sex differences between ankle and knee cartilage morphology determined by quantitative magnetic resonance imaging

OBJECTIVE

To study the correlation between ankle and knee cartilage morphology to test the hypothesis that knee joint cartilage loss in gonarthritis can be estimated retrospectively using quantitative MRI analysis of the knee and ankle and established regression equations; and to test the hypothesis that sex differences in joint surface area are larger in the knee than the ankle, which may explain the greater incidence of knee osteoarthritis in elderly women than in elderly men.

METHODS

Sagittal MR images (3D FLASH WE) of the knee and hind foot were acquired in 29 healthy subjects (14 women, 15 men; mean (SD) age, 25 (3) years), with no signs joint disease. Cartilage volume, thickness, and joint surface area were determined in the knee, ankle, and subtalar joint.

RESULTS

Knee cartilage volumes and joint surface areas showed only moderate correlations with those of the ankle and subtalar joint (r = 0.33 to 0.81). The correlations of cartilage thickness between the two joints were weaker still (r = -0.05 to 0.53). Sex differences in cartilage morphology at the knee and the ankle were similar, with surface areas being -17.5% to -23.5% lower in women than in men.

CONCLUSIONS

Only moderate correlations in cartilage morphology of healthy subjects were found between knee and ankle. It is therefore impractical to estimate knee joint cartilage loss a posteriori in cross sectional studies by measuring the hind foot and then applying a scaling factor. Sex differences in cartilage morphology do not explain differences in osteoarthritis incidence between men and women in the knee and ankle.

Interphalangeal joint cartilage: high-spatial-resolution in vivo MR T2 mapping--a feasibility study

The purpose of this study was to evaluate feasibility of magnetic resonance (MR) T2 mapping of the proximal interphalangeal joint of the index finger. Cartilage T2 maps with an in-plane resolution of 39 microm were obtained from five asymptomatic subjects-four men and one woman, aged 24-45 years-by using a 3.0-T MR imager. Image acquisition time was 9.6 minutes. All cartilage T2 maps demonstrated spatial variation similar to that reported previously for knee cartilage, with T2 values increasing toward the articular surface. These results demonstrate the feasibility of acquiring cartilage T2 maps of small joints in the hand. Application of T2 mapping techniques to non-weight-bearing joints may provide a means for differentiation of local biomechanical and systemic factors that can affect cartilage T2 values.

Detecting structural changes in early experimental osteoarthritis of tibial cartilage by microscopic magnetic resonance imaging and polarised light microscopy

OBJECTIVES

To detect changes in the collagen fibril network in articular cartilage in a canine experimental model of early osteoarthritis (OA) using microscopic magnetic resonance imaging (microMRI) and polarised light microscopy (PLM).

METHODS

Eighteen specimens from three pairs of the medial tibia of an anterior cruciate ligament transection canine model were subjected to microMRI and PLM study 12 weeks after surgery. For each specimen, the following experiments were carried out: (a) two dimensional microMRI images of T(2) relaxation at four orientations; (b) the tangent Young's modulus; and (c) two dimensional PLM images of optical retardance and fibril angle. Disease induced changes in tissue were examined across the depth of the cartilage at a microMRI resolution of 13.7-23.1 microm.

RESULTS

Several distinct changes from T(2) weighted images of cartilage in OA tibia were seen. For the specimens that were covered at least in part by the meniscus, the significant changes in microMRI included a clear shift in the depth of maximum T(2) (21-36%), a decrease in the superficial zone thickness (37-38%), and an increase in cartilage total thickness (15-27%). These microMRI changes varied topographically in the tibia surface because they were not significant in completely exposed locations in medial tibia. The microMRI results were confirmed by the PLM measurements and correlated well with the mechanical measurements.

CONCLUSION

Both microMRI and PLM can detect quantitatively changes in collagen fibre architecture in early OA and resolve topographical variations in cartilage microstructure of canine tibia.

Recommendations for the use of new methods to assess the efficacy of disease-modifying drugs in the treatment of osteoarthritis

BACKGROUND

Recent innovations in the pharmaceutical drug discovery environment have generated new chemical entities with the potential to become disease modifying drugs for osteoarthritis (DMOAD's). Regulatory agencies acknowledge that such compounds may be granted a DMOAD indication, providing they demonstrate that they can slow down disease progression; progression would be calibrated by a surrogate for structural change, by measuring joint space narrowing (JSN) on plain X-rays with the caveat that this delayed JSN translate into a clinical benefit for the patient. Recently, new technology has been developed to detect a structural change of the OA joint earlier than conventional X-rays.

OBJECTIVE

The Group for the Respect of Ethics and Excellence in Science (GREES) organized a working party to assess whether these new technologies may be used as surrogates to plain x-rays for assessment of DMOADs.

METHODS

GREES includes academic scientists, members of regulatory authorities and representatives from the pharmaceutical industry. After an extensive search of the international literature, from 1980 to 2002, two experts meetings were organized to prepare a resource document for regulatory authorities. This document includes recommendations for a possible update of guidelines for the registration of new chemical entities in osteoarthritis.

RESULTS

Magnetic resonance imaging (MRI) is now used to measure parameters of cartilage morphology and integrity in OA patients. While some data are encouraging, correlation between short-term changes in cartilage structure observed with MRI and long-term radiographic or clinical changes are needed. Hence, the GREES suggests that MRI maybe used as an outcome in phase II studies, but that further data is needed before accepting MRI as a primary end-point in phase III clinical trials. Biochemical markers of bone and cartilage remodelling are being tested to predict OA and measure disease progression. Recently published data are promising but validation as surrogate end-points for OA disease progression requires additional study. The GREES suggests that biochemical markers remain limited to 'proof of concept' studies or as secondary end-points in phase II and III clinical trials. However, the GREES emphasizes the importance of acquiring additional information on biochemical markers in order to help better understand the mode of action of drugs to be used in OA. Regulatory agencies consider that evidence of improvement in clinical outcomes is critical for approval of DMOAD. Time to total joint replacement surgery is probably the most relevant clinical end-point for the evaluation of efficacy of a DMOAD. However, at this time, time to surgery can not be used in clinical trials because of bias by non disease-related factors like patient willingness for surgery or economic factors. At this stage, it appears that DMOAD should demonstrate a significant difference compared to placebo. Benefit should be measured by 3 co-primary end-points: JSN, pain and function. Secondary end-points should include the percentage of patients who are 'responder' (or 'failure'). The definition of a 'failure' patient would be someone with progression of JSN>0.5mm over a period of 2-3 years or who has a significant worsening in pain and/or function, based on validated cut-off values. The definition of the clinically relevant cut-off points for pain and function must be based on data evaluating the natural history of the disease (epidemiological cohorts or placebo groups from long-term studies). These cut-offs points should reflect a high propensity, for an individual patient, to later require joint replacement.

CONCLUSION

GREES has outlined a set of guidelines for the development of a DMOAD for OA. Although these guidelines are subject to change as new information becomes available, the information above is based on the present knowledge in the field with the addition of expert opinion.

Whole-Organ Magnetic Resonance Imaging Score (WORMS) of the knee in osteoarthritis

OBJECTIVES

To describe a semi-quantitative scoring method for multi-feature, whole-organ evaluation of the knee in osteoarthritis (OA) based on magnetic resonance imaging (MRI) findings. To determine the inter-observer agreement of this scoring method. To examine associations among the features included in the scoring method.

METHODS

Nineteen knees of 19 patients with knee OA were imaged with MRI using conventional pulse sequences and a clinical 1.5 T MRI system. Images were independently analyzed by two musculoskeletal radiologists using a whole-organ MRI scoring method (WORMS) that incorporated 14 features: articular cartilage integrity, subarticular bone marrow abnormality, subarticular cysts, subarticular bone attrition, marginal osteophytes, medial and lateral meniscal integrity, anterior and posterior cruciate ligament integrity, medial and lateral collateral ligament integrity, synovitis/effusion, intraarticular loose bodies, and periarticular cysts/bursitis. Intraclass correlation coefficients (ICC) were determined for each feature as a measure of inter-observer agreement. Associations among the scores for different features were expressed as Spearman Rho.

RESULTS

All knees showed structural abnormalities with MRI. Cartilage loss and osteophytes were the most prevalent features (98% and 92%, respectively). One of the least common features was ligament abnormality (8%). Inter-observer agreement for WORMS scores was high (most ICC values were >0.80). The individual features showed strong inter-associations.

CONCLUSION

The WORMS method described in this report provides multi-feature, whole-organ assessment of the knee in OA using conventional MR images, and shows high inter-observer agreement among trained readers. This method may be useful in epidemiological studies and clinical trials of OA.