SEARCH

SEARCH BY CITATION

Abstract

  1. Top of page
  2. Abstract
  3. PATIENTS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

Objective

In early rheumatoid arthritis (RA), longitudinal studies have demonstrated that magnetic resonance imaging (MRI) is more sensitive than radiography in demonstrating progressive erosive joint damage. The present study evaluated the progression of erosive damage in patients with established RA by using limited field of view MRI and comparing the results with those obtained by radiography.

Methods

MRI and radiographic studies were available from 47 of 60 patients enrolled in a 2-year RA observational study. MRI of the metacarpophalangeal (MCP) joints was performed at baseline and 2 years later, and a single observer scored all of the MR images with the use of an MRI scoring method developed by the Outcome Measures in Rheumatology Clinical Trials MRI RA study group. MR images from 14 patients were reread by the same observer after 1 week to assess intraobserver reliability. Radiographs were obtained at baseline and at 2 years, and were scored by an observer using the Scott modification of the Larsen score. Radiographs from 14 patients were reread after 1 week to assess the intraobserver reliability. The smallest detectable difference (SDD) was calculated for the MRI scores, the total Larsen scores, and the Larsen scores of the dominant-hand MCP joints (MCPs 2–5) for direct comparison with the MRI results.

Results

The median disease duration was 5.1 years (range 0.5–29 years). Evidence of erosion progression was identified by MRI in 30 patients (64%). The SDD based on the intraobserver scores was calculated as ±3.25 units. Using this result, 11 patients (23%) showed evidence of erosion progression on MRI that was greater than the SDD. The SDD for progression based on the intraobserver total Larsen radiographic scores was 0.77 units, and the SDD for the Larsen scores of the dominant-hand MCP joints was 1.55 units. On the basis of these results, radiographic progression was noted in 19 patients (40%) by the total Larsen score and 7 patients (15%) by the dominant-hand MCP Larsen score. The most striking finding was that although MRI and radiograph scores identified a similar group of patients as having progression of joint damage, the radiographs of both hands appeared to be more responsive to change, albeit with the caveat that radiographic progression was most marked outside the dominant-hand MCP joints.

Conclusion

There was no clear advantage of MRI with a limited field of view as compared with radiographic imaging of both hands in detecting progression of joint damage over 2 years in this group of patients with established RA. The conclusion drawn from this study is not that radiographs are better than MRI or vice versa, but that careful analysis is required to determine the optimal imaging method, or combination of imaging methods, for each study population, depending on the objective and duration of the study.

Although it is clear that preventing structural damage is the primary goal of therapy in rheumatoid arthritis (RA) (1), the most effective means of documenting progression of joint damage is still a contentious issue (2). This is especially the case in patients with established disease, in whom existing erosions and joint malalignment complicate the detection of ongoing damage (3). Furthermore, whereas aggressive treatment is widely accepted to prevent erosion progression in early disease (4, 5), the efficacy of intensive intervention in patients with established disease is less clear. In addition, intervention studies utilizing new therapies often recruit “mixed” cohorts of patients with early and established disease (6–10), understanding the importance of establishing the sensitivity and reliability of available imaging methods in various clinical situations.

Radiographic imaging is widely accepted as the gold standard for the assessment of disease progression in RA. Radiographic scoring systems, such as the Larsen and Sharp scores (11) and their modifications (12, 13), are the standard methods for the determination of joint damage and its progression. However, despite considerable effort to reduce the intrinsic limitations of radiographs, their perceived lack of sensitivity to erosive change in early RA remains a major issue. This has led to the investigation of newer imaging techniques such as magnetic resonance imaging (MRI).

The advantages of MRI of the wrist and metacarpophalangeal (MCP) joints when compared with radiographic imaging are well documented in cross-sectional studies of patients with early disease (disease duration of <12 months) (14–19). In applying MRI to patients whose disease is established, the important issue is whether the promising results in early disease can be reproduced in cohorts of patients with more advanced disease, that is, whether the performance characteristics of MRI are applicable when significant joint damage is already present.

The aim of the present study was therefore to evaluate the progression of erosive damage in the MCP joints of patients with established RA, over a 24-month period using MRI, and to compare these results with the findings on radiographs of both hands, obtained over the same period.

PATIENTS AND METHODS

  1. Top of page
  2. Abstract
  3. PATIENTS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

Study design.

The study was structured to assess progression of joint damage over a 2-year period. The intraobserver reliability for the radiograph and MRI measurements was calculated by comparing the initial radiograph reading and MRI reading with the second radiograph and MRI readings for those patients (baseline and 24 months) who had both images available. The smallest detectable difference (SDD) (20), an absolute method of evaluating measurement error, based on the method described by Bland and Altman (21), was used to assess the progression beyond measurement error for the MRI and radiograph scores (both the total Larsen score of both hands and the dominant-hand MCP Larsen scores). True progression was defined as progression beyond the SDD for the MRI scores and the radiograph scores.

Patients.

Sixty patients with RA were enrolled in a 24-month RA observational study during the period 1998–2002. From this study, 47 patients had complete radiograph and MRI data at baseline and followup, and these patients comprised the study cohort. Patients were recruited from private rooms and outpatient clinics of participating rheumatologists. All patients fulfilled the American College of Rheumatology (formerly, the American Rheumatism Association) diagnostic criteria for RA (22). Patients were taking a variety of disease-modifying antirheumatic drug combinations throughout the course of the study, and this treatment was not altered by the study team.

MRI.

A General Electric Signa Horizon 1.5 Tesla unit (General Electric Signa, Milwaukee, WI) was used for all MRI examinations. MRI of the dominant-hand MCP joints (MCPs 2–5) was performed at baseline and at 24 months using the following sequence: T1 images, repetition time 480 msec, echo time 18 msec, slice thickness 3 mm on coronal images with a 0.3-mm interslice gap, 4 mm on axial images with a 0.4-mm interslice gap, field of view 120 × 120 mm, and matrix 230 × 256 pixels.

Radiographs.

Radiographic studies were performed at baseline and at 24 months using a standard projection. Two views (posteroanterior and oblique) were used for scoring.

MRI interpretation.

The MRI studies were scored by the same observer (PB) in known sequence, using the Outcome Measures in Rheumatology Clinical Trials (OMERACT) MRI RA scoring criteria (23). This score identifies the metacarpal bones and the proximal phalangeal bases of the MCP joints, and scores erosions to a depth of 1 cm from the articular surface. Each bone is assessed for erosions (defined as a break in the cortex of bone in at least one plane) and bone defects. Scoring is based on a 10-point scale, with 0 being no involvement of bone, 5 representing 50% bone loss or involvement, and 10 representing complete destruction or involvement of bone. When the scores from the dominant-hand MCP joints 2–5 are summed, the score may range from 0 to a maximum score of 80. Scoring was repeated at baseline and followup in 14 patients to assess the intraobserver reliability.

Radiograph interpretation.

Radiographs were performed at baseline and 24 months. The radiographs were read in known sequence by 1 reader (JE) using the Scott modification of the Larsen score (24). The Larsen score assesses the degree of joint destruction with a single score from 0 to 5, with the score mainly determined by erosive changes and joint space narrowing (25). In addition to the total Larsen score of both hands, a local Larsen score for the dominant-hand MCP joints 2–5 (i.e., the same joints as in the MRI examination) was calculated to allow direct comparison with the MRI scores of the MCPs. Scoring was repeated by the same observer (JE) at baseline and followup in 14 patients (the same group as in the MRI) to assess the intraobserver reliability.

All MRI and radiograph readings were conducted independently by each observer without knowledge of the other reader's scores.

Statistical analysis.

Statistical analysis was undertaken using SPSS version 10 (26). Intraclass correlation coefficient (ICC) values were calculated for the intraobserver scores using a 2-way mixed model with absolute agreement (i.e., random effects ICC) and a 95% confidence interval. The ICC was calculated for status data (baseline and 24-month scores) as well as for progression scores.

The SDD (20) was used to assess the progression beyond measurement error for the MRI and radiograph scores (both the total Larsen score of both hands and the dominant-hand MCP Larsen scores). The SDD was calculated for MRI and radiograph progression scores based on the intraobserver progression scores, using the following formula:

  • equation image

where MRI 1 is the MRI scan at baseline, MRI 2 is the MRI scan at 24 months, and R1 and R2 represent readings 1 and 2, respectively. The same formula was used for the radiograph readings except that radiograph (XR) was substituted for MRI in the formula.

The SDD is one of several distribution-based methods of determining whether the outcome of interest (in this study, MRI or radiographic damage) has really changed over time. We used the random error component of Bland and Altman's limits of agreement (21) to calculate the measurement error based on the SDD. This must be determined from a reliability study. The formula for the SDD is given by ±(t0.05 × SDdifference). In this study, we calculated the difference for each paired observation and obtained the standard deviation of these differences (SDdifference). The SDdifference is multiplied by the t value, which is based on the size of the sample, to calculate the 95% confidence limits around the SDdifference. This means that if the difference scores are normally distributed, 95% of the differences between repeated measurements would lie between −(t0.05 × SDdifference) and +(t0.05 × SDdifference). In this study, therefore, a 95% probability of true progression represented by the SDD was accepted as true progression.

RESULTS

  1. Top of page
  2. Abstract
  3. PATIENTS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

The mean age of subjects was 59 years and the mean disease duration of the group was 5.1 years (range 0.5–29 years). Ten patients (21%) had a disease duration of <2 years at study entry.

MRI damage progression was initially defined as any progression in the MRI damage score from the MRI damage score at baseline. Using this criterion, MRI evidence of erosion progression was identified in 30 patients (64%). Progression was then defined more stringently by applying the SDD based on the intraobserver scores (±3.25 units). Using this definition, 11 patients (23%) showed MRI evidence of erosion progression that was greater than the SDD (Table 1).

Table 1. Damage progression scores as determined by magnetic resonance imaging (MRI) compared with radiography*
Imaging modalityOMERACT MRI RA score of MCPs 2–5 of dominant handRadiographs, total Larsen score of both handsRadiographs, Larsen score of MCPs 2–5 of dominant hand
  • *

    See Patients and Methods for a detailed description of the methods used to calculate the intraobserver smallest detectable difference (SDD). The SDD is expressed as a raw value and as a percentage of the actual maximum score. MCP = metacarpophalangeal; OMERACT MRI RA score = Outcome Measures in Rheumatology Clinical Trials MRI rheumatoid arthritis score.

  • MRI and radiographic damage progressors are those patients with progression scores greater than the SDD based on the intraobserver scores.

SDD3.250.771.55
 % of actual maximum score4.220.786.2
Number of damage progressors with >SDD11197
 Study identification numbers of damage progressors5, 15, 20, 30, 35, 41, 49, 50, 51, 53, 555, 8, 13, 14, 15, 17, 18, 20, 26, 30, 35, 36, 41, 45, 47, 49, 50, 51, 5318, 26, 30, 41, 47, 49, 53

For the radiographs, the SDD based on the intraobserver total Larsen scores was 0.77 units and the SDD for the dominant-hand MCP joints 2–5 was 1.55 units. On the basis of these results, radiographic progression was noted in 19 patients (40%) by the total Larsen score and 7 patients (15%) by the dominant-hand MCP Larsen score (Table 1).

Comparisons between MRI progression and total Larsen score radiographic progression results showed that a similar group of patients were identified as having progression (damage progressors) by both methods, but the radiographs of both hands identified more progressors overall than did MRI with limited field of view (Table 2). For the 9 patients who showed progression of joint damage on radiographs that was not detected by MRI, the majority (66%) exhibited this radiographic progression outside the dominant-hand MCP joints. Three patients, however, did have evidence of radiographic progression in the dominant-hand MCP joints that was not detected by MRI. There were 7 patients who showed evidence of progression in the dominant-hand MCP joints on MRI that did not have evidence of progression when the limited (dominant-hand MCPs 2–5) Larsen score was applied to the radiographs.

Table 2. Differences between imaging methods in the determination of damage progression*
Imaging methodMRI progressors not identified by total Larsen scoreTotal Larsen score progressors not identified by MRILarsen score MCPs 2–5 progressors not identified by MRIMRI progressors not identified by Larsen score MCPs 2–5
  • *

    See Patients and Methods for a detailed description of the methods used to calculate the intraobserver SDD. MRI and radiograph damage progressors are those patients with progression scores greater than the SDD based on the intraobserver scores. See Table 1 for definitions.

Number of patients1937
Study identification numbers of damage progressors558, 13, 14, 17, 18, 26, 36, 45, 4718, 26, 475, 15, 20, 35, 50, 51, 55

DISCUSSION

  1. Top of page
  2. Abstract
  3. PATIENTS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

This study compared MRI examination of the MCP joints of one hand with standard radiographic examination of both hands as assessment methods for damage progression over 2 years in patients with established RA. The results demonstrate that radiographs appear to be more responsive to progression of joint damage in this group of patients. Although both methods identified a similar group of damage progressors, the radiographs were more responsive, largely because of identification of progression in joints outside the field of view of the MRIs. As expected, MRI demonstrated greater sensitivity to damage progression in the MCP joints alone, but did not show an advantage when compared with the total Larsen radiographic scoring of both hands.

This study raises a number of issues that merit further comment. These issues include the role of observer error in scoring damage progression, the importance of the joint sample in evaluating damage progression, the influence of the MRI acquisition parameters, the content validity of the scoring methods, and the effect of the prolonged observation period.

With regard to the role of observer error, damage progression can be judged by changes in the raw score or, more rigorously, by changes that exceed the measurement error as indicated by the SDD. In this study, the SDD was measured using the intraobserver reliability, and the criterion for progression was defined as a change greater than the measurement error, i.e., greater than the SDD of the progression scores. It is important to note that SDDs calculated on progression scores, rather than on cross-sectional data, often lead to lower SDD values as a result of lower scores, since progression scores are usually smaller than cross-sectional scores. The SDD as a percentage of the actual maximum score was slightly higher for the MRI reader, but not sufficiently different to suggest that there was significantly greater intraobserver error in the MRI scoring.

However, because the SDDs for both the total Larsen score (0.77) and for the MCP joints alone (1.55) were small, it is relevant to speculate on the effect of greater variability in the radiograph reading on the study outcome. As stated in Patients and Methods, the reliability studies provided a 95% probability of true progression in the results presented. If an 80% probability of real progression is applied, the results, and therefore the conclusion of this study, do not change significantly. If a 67% probability of real progression is applied, the results alter to the extent that MRI demonstrates slightly more real progression than does the total Larsen score. Such a low probability of real change is based on a 33% error, which is unrealistically high for studies conducted by experienced investigators. Nonetheless, the point to note is that measurement error affects the results of comparative studies such as the present study, and not only is it important that the SDD is comparable in terms of its percentage of the actual maximum score (Table 1), but also it is essential that a rigorous application of the method is undertaken (i.e., 95% probability of true progression) to ensure that the results reflect real progression.

With regard to the importance of the joint sample in evaluating damage progression, adequate representation of progressive joint damage is important for patients with RA, at any stage of the disease process. Of the 19 patients identified as progressors by the total Larsen score, 9 were not identified as progressors by the limited-field MRI examination. Therefore, although both methods identified a similar group of patients with progressive disease, radiographs of both hands were clearly more responsive in this group of patients, largely due to progression in joints not included in the limited MRI study (Table 2). However, direct comparison between the dominant-hand MCP MRI and the Larsen score from the corresponding area showed that MRI was more sensitive in detecting erosive change in this subset of joints (Figures 1 and 2).

thumbnail image

Figure 1. Baseline (A) and year 2 (B) radiographs obtained from patient 50 in a 24-month rheumatoid arthritis observational study during the period 1998–2002. Radiographs are of the dominant-hand metacarpophalangeal joints 2–5. At both time points, the Larsen radiographic damage score is 0. Although there appears to be an abnormality in the third metacarpal head (B), the defect does not qualify as an erosion using the Larsen scoring method, and there is no appreciable joint space narrowing.

Download figure to PowerPoint

thumbnail image

Figure 2. Baseline (A) and year 2 (B) magnetic resonance imaging (MRI) of the dominant-hand metacarpophalangeal joints 2–5 from patient 50 in a 24-month rheumatoid arthritis observational study during the period 1998–2002. The coronal and axial MRIs show erosion (arrows in A) and progression of erosion (arrows in B) in the third metacarpal.

Download figure to PowerPoint

It should also be noted that the feet were not included in the radiographic analysis in this study. Perhaps inclusion of assessment of structural damage in the feet may have reinforced the results of this study, bringing radiographs into an even more favorable position by virtue of an increase in joint coverage.

Another consideration is whether the MRI sequence protocol was a factor in reducing the sensitivity of MRI. Slice thickness may be important in this regard; thinner slices would be expected to be more sensitive in detecting small erosions, but the trade-off is a reduction in the signal-to-noise ratio, which produces a less clear image so that, in theory, erosions may be more difficult to identify and measurement may be less accurate. In this study, 3-mm slice thicknesses with a 0.3-mm gap were utilized so that effectively there was a 3.3-mm gap between slices in the coronal plane. It is possible that this reduced the sensitivity of the MRI to detect small erosions, and may be a contributing factor in the apparent lack of sensitivity of MRI in this study.

A further issue is whether the scoring method used for MRI is comprehensive enough to document change. The scores for MRI include only erosions, whereas the Larsen score includes joint space narrowing as part of the total score; this may have contributed to the superior performance of the total Larsen score. This is suggested by the 3 patients with evidence of progression in the MCPs on radiographs that was not detected by MRI. Reanalysis of radiographs using the Sharp score confirmed this suspicion, with all 3 showing the majority of progression via change in joint space narrowing, rather than erosion progression.

Other methods of MRI erosion measurement are becoming available; for example, computerized measurement of erosive damage on MRI has been shown to be comparable with the OMERACT MRI RA score (27) and has shown excellent reliability in cross-sectional trials. However, in this study, the MR sequences were not adequate for computerized analysis because the slice thickness and interslice gap did not permit accurate computerized volume analysis in the MCP joints for the majority of patients.

Furthermore, the length of the observation period is important in judging the superiority of one imaging technique over another. We chose an interval that would allow for a period of change, in this observational study, sufficient to allow adequate comparison of the 2 imaging techniques. A shorter period would probably have skewed the results in favor of the MRI; the relatively long followup may have skewed the results in favor of radiographs. However, it is impossible to be certain without the benefit of serial measurements. Nevertheless, it is important to note that the results of our study pertain specifically to change over a 2-year period.

Finally, with regard to other longitudinal studies in established disease, comparisons of MRI and radiographs in longitudinal studies of patients with established RA are limited in number. Using 2 separate established disease cohorts, Ostergaard et al reported that MRI identified more erosions than did radiographs in 26 patients over 12 months (28) and 10 patients over a 5-year period (29). Erosions were counted, rather than scored, and in contrast to our study, enlargement of an existing erosion or the development of a new erosion in a previously eroded bone was not regarded as progression. Intraobserver reliability for the erosion scores was not recorded in those studies. These disparities illustrate the importance of the measurement method and the principle that the minimization of measurement error is a central issue in studies of damage progression.

The results of this study indicate that although MRI was more sensitive than radiographs within a restricted field of view, overall there is no clear advantage of MRI over radiographs in documenting damage progression in patients with established RA. However, this result must be interpreted strictly within the constraints of the project: a cohort with long-term disease, an observation period of 2 years, the MRI acquisition and scoring system used, and the assessment of the dominant-hand MCP joints rather than the carpus.

The conclusion that can be drawn from this study is not simply that radiographs are better than MRI or vice versa, but that careful further study and analysis is required to determine the optimal imaging method for the task, whether that be detection of erosive change over short periods in early disease or the assessment of more global damage progression over longer periods in established disease. To be able to select the most appropriate technique from the diverse array of methods now available, we need clear data on the validity, reliability, and sensitivity of each method in different disease stages and study settings. The results of this study contribute to the development of such a database.

REFERENCES

  1. Top of page
  2. Abstract
  3. PATIENTS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES
  • 1
    American College of Rheumatology Subcommittee on Rheumatoid Arthritis Guidelines. Guidelines for the management of rheumatoid arthritis: 2002 update. Arthritis Rheum 2002; 46: 32846.
  • 2
    Strand V, Sharp JT. Radiographic data from recent randomized controlled clinical trials in rheumatoid arthritis: what have we learned? Arthritis Rheum 2003; 48: 2834.
  • 3
    Van der Heijde DM. Plain X-rays in rheumatoid arthritis: overview of scoring methods, their reliability and applicability. Baillieres Clin Rheumatol 1996; 10: 43553.
  • 4
    Emery P. The optimal management of early rheumatoid disease: the key to preventing disability. Br J Rheumatol 1994; 33: 7658.
  • 5
    Stenger A, van Leeuwen M, Houtman P, Bruyn G, Speerstra F, Barendsen B, et al. Early effective suppression of inflammation in rheumatoid arthritis reduces radiographic progression. Br J Rheumatol 1998; 37: 115763.
  • 6
    Cohen S, Cannon G, Schiff M, Weaver A, Fox R, Olsen N, et al. Two year, blinded, randomized, controlled trial of treatment of active rheumatoid arthritis with leflunomide compared with methotrexate: Utilization of Leflunomide in the Treatment of Rheumatoid Arthritis Trial Investigators Group. Arthritis Rheum 2001; 44: 198492.
  • 7
    Sharp J, Strand V, Leung H, Hurley, Loew-Friedrich I, for the Leflunomide Rheumatoid Arthritis Investigators Group. Treatment with leflunomide slows radiographic progression of rheumatoid arthritis: results from three randomized controlled trials of leflunomide in patients with active rheumatoid arthritis. Arthritis Rheum 2000; 43: 495505.
  • 8
    Scott D, Smolen J, Kalden J, van de Putte L, Larsen A, Kvien T, et al. Treatment of active rheumatoid arthritis with leflunomide: two year follow up of a double blind, placebo controlled trial versus sulfasalazine. Ann Rheum Dis 2001; 60: 91323.
  • 9
    Moreland LW, Schiff MH, Baumgartner SW, Tindall FA, Fleischmann RM, Bulpitt KJ, et al. Etanercept therapy in rheumatoid arthritis: a randomized, controlled trial. Ann Intern Med 1999; 130: 47886.
  • 10
    Lipsky PE, van der Heijde DM, St Clair EW, Furst DE, Breedveld FC, Kalden JR, et al. Infliximab and methotrexate in the treatment of rheumatoid arthritis: Anti-Tumor Necrosis Factor Trial in Rheumatoid Arthritis with Concomitant Therapy Study Group. N Engl J Med 2000; 343: 1594602.
  • 11
    Larsen A, Dale K, Eek M. Radiographic evaluation of rheumatoid arthritis and related conditions by standard reference films. Acta Radiol Diagn (Stockh) 1977; 18: 48191.
  • 12
    Scott DL, Laasonen L, Priolo F, Houssein DA, Bacarini L, Cerase A, et al. The radiological assessment of rheumatoid arthritis. Clin Exp Rheumatol 1997; 15 Suppl 17: S5361.
  • 13
    Van der Heijde DM. How to read radiographs according to the Sharp/van der Heijde method. J Rheumatol 1999; 26: 7435.
  • 14
    McQueen FM, Stewart N, Crabbe J, Robinson E, Yeoman S, Tan PL, et al. Magnetic resonance imaging of the wrist in early rheumatoid arthritis reveals a high prevalence of erosions at four months after symptom onset. Ann Rheum Dis 1998; 57: 3506.
  • 15
    Foley-Nolan D, Stack JP, Ryan M, Redmond U, Barry C, Ennis J, et al. Magnetic resonance imaging in the assessment of rheumatoid arthritis: a comparison with plain film radiographs. Br J Rheumatol 1991; 30: 1016.
  • 16
    Jorgensen C, Cyteval C, Anaya JM, Baron MP, Lamarque JL, Sany J. Sensitivity of magnetic resonance imaging of the wrist in very early rheumatoid arthritis. Clin Exp Rheumatol 1993; 11: 1638.
  • 17
    Klarlund M, Ostergaard M, Jensen KE, Madsen JL, Skojdt H, Lorenzen I, for the TIRA Group. Magnetic resonance imaging, radiography and scintigraphy of the finger joints: one year follow up of patients with early arthritis. Ann Rheum Dis 2000; 59: 5218.
  • 18
    McGonagle D, Conaghan P, Wakefield D, Emery P. Imaging the joints in early rheumatoid arthritis. Ballieres Best Pract Res Clin Rheumatol 2001; 15: 91104.
  • 19
    Lindegaard H, Vallo J, Horslev-Petersen K, Junker P, Ostergaard M. Low field dedicated magnetic resonance imaging in untreated rheumatoid arthritis of recent onset. Ann Rheum Dis 2001; 60: 7706.
  • 20
    Lassere M, Boers M, van der Heijde D, Boonen A, Edmonds J, Saudan A, et al. Smallest detectable difference in radiological progression. J Rheumatol 1999; 26: 7319.
  • 21
    Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986; 1: 30710.
  • 22
    Arnett FC, Edworthy SM, Bloch DA, McShane DJ, Fries F, Cooper NS, et al. The American Rheumatism Association 1987 revised criteria for the classification of rheumatoid arthritis. Arthritis Rheum 1988; 31: 31524.
  • 23
    Conaghan P, Edmonds J, Emery P, Genant H, Gibbon W, Klarlund M, et al. Magnetic resonance imaging in rheumatoid arthritis: summary of OMERACT activities, current status, and plans. J Rheumatol 2001; 28: 115862.
  • 24
    Edmonds JP, Saudan A, Lassere M, Scott D. Introduction to reading radiographs by the Scott modification of the Larsen method. J Rheumatol 1999; 26: 7402.
  • 25
    Van der Heijde DM. Plain X-rays in rheumatoid arthritis: overview of scoring methods, their reliability and applicability. Baillieres Clin Rheumatol 1996; 10: 43553.
  • 26
    Statistical Package for the Social Sciences for Windows, version 10. Chicago: SPSS; 2001.
  • 27
    Bird P, Lassere M, Shnier R, Edmonds J. Computerized measurement of magnetic resonance imaging erosion volumes in patients with rheumatoid arthritis: a comparison with existing magnetic resonance imaging scoring systems and standard clinical outcome measures. Arthritis Rheum 2003; 48: 61424.
  • 28
    Ostergaard M, Hansen M, Stoltenberg M, Gideon P, Klarlund M, Jensen KE, et al. Magnetic resonance imaging–determined synovial membrane volume as a marker of disease activity and a predictor of progressive joint destruction in the wrists of patients with rheumatoid arthritis. Arthritis Rheum 1999; 42: 91829.
  • 29
    Ostergaard M, Hansen M, Stoltenberg M, Jensen K, Szkudlarek M, Pedersen-Zbinden B, et al. New radiographic bone erosions in the wrists of patients with rheumatoid arthritis are detectable with magnetic resonance imaging a median of two years earlier. Arthritis Rheum 2003; 48: 212831.