The value of conventional views and radiographic magnification in evaluating early rheumatoid arthritis.
код для вставкиСкачать744 THE VALUE O F CONVENTIONAL VIEWS AND RADIOGRAPHIC MAGNIFICATION IN EVALUATING EARLY RHEUMATOID ARTHRITIS ROBERT M. HARTLEY, MATTHEW H. LIANG, BARBARA N. WEISSMAN, J. LELAND SOSMAN, ROBEKT KATZ, and JOHN R. CHARLTON Fifty-four patients with suspected early rheumatoid arthritis had radiographs taken of their hands and wrists in 4 views (posteroanterior [PA], oblique, reverse oblique, and Brewerton) using conventional techniques and, in the PA view, using radiographic magnification. The radiographs were “masked” and presented in random order to 2 radiologists specializing in bone and joint radiology who interpreted them for malalignment, erosions, joint space narrowing, and soft tissue swelling. The PA was the best conventional view for demonstrating malalignment, joint space narrowing, and soft tissue abnormalities; the Brewerton view was better for detecting erosive disease. Radiographic magnification was more sensitive than conventional films for evaluating erosive disease, but otherwise was no better than the conventional PA view. These results help the physician choose the radiologic technique or combination of techniques that is most likely to detect specific abnormalities. From the Robert B. Brigham Multipurpose Arthritis Center and the Departments of Medicine, Rheumatology and Immunology. and Radiology, Harvard Medical School, Brigham and Women’s Hospital, Boston, Massachusetts. Supported by National Institutes of Health grant AM20580. Robert M. Hartley, MD, MSc: Milbank Memorial Fund Scholar; Matthew H. Liang, MD, MPH; Barbara N. Weissman, MD; J . Leland Sosman, MD; Robert Katz, BA: Department of Clinical Psychology, Syracuse University, Syracuse, New York; John R. Charlton, MSc: Department of Community Medicine, St. Thomas’s Hospital Medical School. London, England. Address reprint requests to Dr. Robert M. Hartley, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 021 IS. Submitted for publication April 11, 1983; accepted in revised form March 12, 1984. Arthritis and Rheumatism, Vol. 27, No. 7 (July 1984) Radiographic imaging is an important tool in the evaluation of arthritic disorders, particularly in rheumatoid arthritis (RA). Detection of erosions is of particular diagnostic and prognostic importance. In the appropriate clinical setting erosions are diagnostic of RA, and because they indicate structural damage, suggest the need for aggressive therapy (1-3). The finding of soft tissue swelling in the proximal interphalangeal joints, metacarpophalartgeal joints, and about the ulnar styloid also strongly suggests the diagnosis of RA, even in the absence of erosions (4). A number of different radiographic techniques and projections are available for joint imaging. For the hands and wrists, the posteroanterior (PA), oblique, reverse oblique, and Brewerton projections are commonly used “conventional views” of the hand. A “routine” examination may involve any combination of these projections. Which of these views or combination of views is most efficient in demonstrating the radiographic abnormalities of RA has not been systematically studied. Fine-detail radiography using industrial quality, fine-grained film with optical magnification has been shown to be useful in the detection of early erosive disease (5,6) but is not in widespread use. A more recent development, direct radiographic magnification, offers distinct advantages compared with optical magnification. In particular, it gives less radiation and does not require special processing and viewing equipment. Compared with conventional radiography, radiographic magnification gives about 4 times the skin dose, though the total dose still remains quite low, 4 0 mR (7). Radiographic magnification is more expensive. The equipment can only be used for magnification RADIOGRAPHIC EVALUATION OF RA Figure 1. Radiographs of hands in the A, posteroanterior. B, oblique, C, reverse oblique, and D, Hrewerton positions. 745 HARTLEY ET AL 746 films, and in addition to this fixed cost, we estimate that, compared with conventional techniques, the marginal costs of film, processing, and technician time are about 5 dollars per PA magnification examination of both hands. Genant and his colleagues compared the image quality of optical and radiographic magnification techniques and showed that for thin objects such as the hahd, the former provides somewhat better images (6,8,9). Both magnification techniques produce images superior to those of conventional radiography. In a recent study using optical magnification to examine 25 patients, Genant provided evidence suggesting that this technique is more sensitive than conventional radiologic methods for detecting erosions and soft tissue swelling (10). However, the clinical utility of radiographic magnification has had little evaluation. In one study, 2 radiologists were asked to comment upon the diagnostic information available in magnification and conventional films of 212 patients (7). Magnification was thought to provide substantially more “helpful” information than codventional radiography in arthritic disorders. However, in only 5% of the cases was the additional iriformation considered “essential” for diagnosis. In another study, Ishigaki fouhd that 50% of small bone defects noted in 28 patients with gout were found only by using a 6x radiographic maghification view (I 1). In this stlldy we sought to determine which of 4 conventional views is most sensitive in detecting the abnormalities associated with early rheumatoid arthritis, and whether radiographic magnification provided additional sensitivity. PATIENTS AND METHODS All patients were seen ih a 96-bed unit specializing in the care of rheumatologic and orthopedic patients. Criteria for admission to the study were: diagnosis of probable or possible rheumatoid arthritis, joint symptoms for less than 2 years, and no gross erosions on routine PA hand film. Patients who met these criteria were examined radiagraphically using 5 different techniques: PA, Brewerton, oblique, and reverse oblique views were taken of both hands and wrists using standard technology (the “conventional” films, Figures 1A-D), and a PA radiographic magnification film was taken of the right hand and wrist, using an RSI microfocus tube with 0.09-mm focal spot. Patients were positioned with hands palm down on a plexiglass platform. The targetfilm distance and object-film distance were set to achieve 2x magnification. Trimax 2 screens and XUD film were used with standard processing. Each film was coded, masked, and presented in random order to 2 radiologists specializing in bone and joint radiology, both of whom have more than 10 years of specialty experience. Because we wished to study the use of these techniques in everyday reading conditions, the radiologists were not permitted to confer on their observations nor to use standard comparison films. Each joint was inspected for malalignment, erosions, joint space narrowing, and soft tissue swelling. Twenty-three joints on each hand and wrist were evaluated for the first 3 abnormalities, and 24 for the fourth. Each joint was described as “normal,” “questionably abnormal,” or “definitely abnormal.” Computer outputs were checked against transcripts of the original dictations to insure accuracy of data entry. Logistic multiple regression was used in the analysis of the data for 2 reasons (12). First, observations ofjoints on the hands of the same patient cannot be truly independent, and therefore, a model that adjusts for this lack of independence is required. Second, we wished to assess the effect of each technique upon the detection of positive finding: but knew that differences between right and left hands, patients, and particularly between observers might obscure this effect. Logistic multiple regression can be used to adjust for these factors that are of lesser ihterest so that the effects of radiographic view and magnification can be more clearly evaluated. The basic model used for analysis expressed the number of positive findings as a function of 4 independent variables: hand (left or right), radiologist ( 1 or 2), patient (1 through 54), and technique (the 4 named above). The “standardized logits” used in the figures express the proportions of all joints found to be positive after transformation re- Table 1. Numbers of questionably abnormal (QA) and definitely abnormal (DA) joints according to radiologic technique and abnormality as read by radiologist 1 Abnormality Erosions View Posteroantetior Oblique Reverse oblique Brewerton Radiographic magnification* Alignment Joint space narrowing Soft tissue swelling QA DA QA DA QA DA QA DA I79 149 I27 I24 39 36 24 55 52 50 31 16 9 5 10 I79 I46 89 125 175 I28 67 97 200 204 I42 152 I25 126 52 77 84 78 23 25 87 70 171 80 14 * Since radiographic magnification views were taken only of the right hand, there were half as many joints examined per film Total number of films 54 54 41 54 54 RADIOGRAPHIC EVALUATION OF RA 747 Table 2. Numbers of questionably abnormal (QA) and definitely abnormal (DA)joints according to radiologic technique and abnormality as read bv radioloaist 2 Abnormality Erosions View Posteroanterior Oblique Reverse oblique Brewerton Radiographic magnification * ~~ Alignment Soft tissue swelling Joint space narrowing QA DA QA DA QA DA QA DA Total number of films 29 39 39 51 13 II 28 33 8 I 3 0 26 13 7 9 75 101 24 IS I19 88 43 88 57 52 30 39 13 41 26 40 54 54 54 54 I 20 30 89 51 so 54 23 12 ~~ ~~ * Since radiographic magnification views were taken only of the right hand, there were half as many joints examined per film. quired to comply with the assumptions of linear modeling. At 0 the logit equals a proportion of 0.5, while negative numbers are less and positive numbers are more than a proportion of 0.5. Separate analyses were conducted for each abnormality, counting either questionably abnormal or definitely abnormal joints. The goodness of fit of the logit models to the data was assessed by examining deviance after fitting the model (deviance is -2 times log-likelihood and is distributed asymtotically as chi-square) (13). The estimates provided by the model for the various radiologic techniques were compared statistically by using 2-tailed [-tests (12). Unless otherwise stated, all significance tests were conducted at the 1% level, thereby allowing for multiple testing. Also determined was a measure of observer agreement for each technique. This was calculated as the sum of the numbers of joints which the radiologists agreed were normal, questionably abnormal, o r definitely abnormal, divided by the number of joints read. were women whose mean age was 55.4 years (range 28-79); the 11 men also had a mean age of 55.4 years (range 36-71). Comparison of radiologists. Tables I and 2 present the 2 radiologists' findings using each technique. Radiologist 1 consistently recorded more findings, questionable and definite, regardless of the technique or abnormality being evaluated. Interobserver agree- ;I b Qucrtiomblc Erosions s'-2.5 RESULTS -3.0 Forty-one patients had complete sets of 5 films read by both radiologists; 13 had 1 film missing (the reverse oblique). Analyses were also performed using only the 41 patients with complete sets of films; the conclusions were unchanged. Forty-three patients .3.5 01 -2.5 ;-.5 -3.0 $4.0 .-1.5 PA 0. no I" Deviances for various models* Full Abnormality Alignment Erosions Joint space narrowing Soft tissue swelling Degrees of freedom 9 -4.0 s' Without technique NO variables 296 625 952 782 890 * Distributed asymtotically as x2. All comparisons between models for a particular abnormality significant at P < 0.001. t Full = radiologist + radiologic view + hand + patient; without technique = radiologist + hand + patient. ; -3.5 -5.0 84 I 1,204 3,412 2,026 945 I I -3.0 j -4.5 .s 242 568 900 139 881 .Y .. -3.5 Modell g: Definilc loin1 Space Narrowing -2.0 I -3.5 Table 3. I L c: Qucrliorvblc loin1 Space Narrowing 01 I0 . -4.0 .A "M I 1 0. 10 I. IH I Figure 2. Comparison of sensitivities of techniques. Sensitivities of each technique in detecting each of the radiographic abnormalities expressed as standardized logits of the proportion of joints found positive. (Taller bars indicate greater sensitivity.) PA = posteroanterior; OB = oblique; RO = reverse oblique; BK = Brewerton; RM = radiographic magnification. **P< 0.001 compared with PA view. ' P < 0.01 compared with Brewerton view (examined for definite erosions only). HARTLEY ET AL 748 7 1 DIP PIP MCP WRIST Figure 3. Comparison of sensitivities of radiographic techniques at different joints. Percent of joints demonstrating dcfinite erosions according to location and technique. DIP = distal interphalangeal; PIP = proximal intcrphalangeal; MCP = metacarpophalangeal; wrist = midcarpal, radiocarpal, and ulnocarpal: PA = posteroantcrior; OB = oblique; RO = reverse oblique; BR = Brewerton; RM = radiographic magnification. ment ranged from 81 to 92% on the 5 views for the 4 abnormalities. To some extent, the low prevalence of abnormalities masks the degree of interobserver variation in recording questionable and definite findings. Detailed analysis of this variation will be the subject of a future report. Comparison of radiologic views. Linear modeling techniques were employed to analyze the ability of the various techniques to detect each of the 4 radiographic abnormalities. Table 3 presents the chisquares (x’) and the degrees of freedom (df) for the models. The “full” model analyzed the number of findings on each film as a function of 4 independent variables: radiologist, hand (left or right), patient, and technique. The “without technique” model did not include this last variable. By comparing the x’ of the “full” models used for our analysis with their respective df, it may be seen that the models adequately describe the data (the x2 are about the same or less than their df). Comparing the “full” and “without technique” models shows that the “technique” parameter is highly significant in the additional variation it explains. This indicates that significant differences exist among the radiologic techniques in the number of findings noted on them. Results are presented only for definite findings; similar values were also obtained for readings scored “questionable.” Figures 2a-h present the results separately for each radiologic abnormality and the 2 scorings, questionably or definitely abnormal. For most of the abnor- A Figure 4. Two views of rheumatoid erosions. A, The posteroantcrior view shows erosion of the proximal phalanx of the index finger and a small cyst-like lucency in the proximal phalanx of the third finger (3). B, The magnification view shows the erosion of the index proximal phalanx (arrow) to advantage. 749 RADIOGRAPHIC EVALUATION OF RA magnification were the superior views for detection of erosions about the metacarpophalangeal and proximal interphalangeal joints. This point is demonstrated in Figures 4 and 5 . DISCUSSION Figure 5. The Brewerton view of the hand shown in Figures 4A and B (note order of fingers reversed) shows an erosion of the proximal phalanx of thc third finger (3) that was not demonstrated on the other views (arrow). A probable erosion of the third metacarpal head, not previously evident, is also present in this view. malities, the relative sensitivities of the techniques are similar for both questionable and definite findings. Comparing conventional techniques, more questionable and definite alignment, soft tissue, and joint space abnormalities were noted on the standard PA film than on any of the other 3. In many instances, these differences were statistically significant despite the relatively small number of total findings. However, for erosive disease the PA was 1 of the 2 least sensitive views. The Brewerton view, which was the least sensitive for 2 of the other 3 abnormalities, was significantly better than the PA in the detection of erosions (Figure 20. Compared with the conventional films in the detection of alignment, joint space, and soft tissue abnormalities, the magnification technique showed results most like the standard PA. However, it was much better than the PA in detecting definite erosive changes and also was significantly better than the Brewerton (Figure 20. Figure 3 compares the sensitivities of the techniques at different joints. When compared with the PA, the Brewerton and radiographic The methodology of this study enabled separate analyses to be made of the sensitivities of each view and of radiographic magnification in detecting the 4 abnormalities that are typical of early RA. Comparison of the PA magnification film with the conventional PA film isolates the effect of magnification while the effects of the different views can be determined by comparison of the conventional films. Our results show that the usefulness of each of the conventional views depends upon the location and type of radiographic abnormality being sought. They also demonstrate that radiographic magnification has the ability to provide additional information, though not about all types of abnormalities. For the detection of malalignment, joint space narrowing, and soft tissue swelling, the PA is the best conventional view. The others-the oblique, reverse oblique, and particularly the Brewerton-diminish the radiologist’s ability to properly view fat planes and joint spaces, thereby making these views less able to demonstrate these particular abnormalities. Radiographic magnification added little further information. Therefore, for malalignment, joint space narrowing, and soft tissue swelling, the view, rather than the use of magnification, determines sensitivity. Our findings suggest that different radiologic abnormalities, even those occurring in the same anatomic areas, may be best evaluated by different views. In this study, the PA was one of the least sensitive views in the detection of erosions. The Brewerton and reverse oblique, the 2 least sensitive in evaluating the other 3 abnormalities, performed better than the PA in the detection of erosive disease. Similarly, Norgaard has argued that the reverse oblique is more sensitive in detecting erosions (14,15), although others have disputed that claim (16,17). Our findings would also indicate that the PA may not be the single best conventional film for detecting erosions. The anatomic distribution of erosions noted on the Brewerton suggests that, compared with the PA, it enables better visualization of the joints most classically involved in RA . In contrast to the other 3 abnormalities, both 750 the particular view and the use of magnification appear important in determining sensitivity to erosive disease. Our magnification film was a PA view and was more sensitive than all the conventional films, including the conventional PA, in detecting erosions. Using optical magnification technique, Genant similarly demonstrated it to be more sensitive than conventional PA and oblique films in detecting erosive disease (10). The use of magnification, therefore, more than offset the disadvantage of the PA view which, as indicated by comparison of the conventional views, was not the optimal view for detecting erosions. It is quite possible that magnification films taken in Brewerton or reverse oblique views may perform even better than our PA magnification film in detecting erosions. Two further comments should be made. First, in comparative studies such as this, no independent verification of the findings exists. Since it is not known how many patients presenting with possible or probable RA may have abnormalities, especially on a magnification film, the use of control films of “normal” subjects may aid in ascertaining whether the falsepositive rate is likely to be high. However, this control still would not allow for the calculation of indices of test performance. In this study, we have assumed that findings scored as questionably or definitely abnormal reflect the ability of specific techniques relative to one another to demonstrate the abnormalities sought. Second, we provide evidence that particular techniques provide more information. Whether diagnosis or clinical management would be altered by this information has not been determined and deserves further study. For the practicing physician having to decide what radiographs to order, this study helps clarify the options. If radiographic magnification is either unavailable or the added radiation exposure thought inappropriate, then the PA is clearly the single best screen for the 4 abnormalities we have studied. The addition of a Brewerton, or possibly a reverse oblique, may enhance the ability to detect erosive disease, though at the cost of additional radiation and expense. If only erosive disease is of interest, then we have found the Brewerton to be the single best view. The decision to order radiographic magnification instead of a conventional film depends upon the importance of detecting subtle erosive changes. In specific situations, such as evaluating whether to use possibly toxic drugs, the detection of such erosions may be quite important and thereby justify the use of radiographic magnification. However, another radio- HARTLEY ET AL graphic sign of destructive disease, joint space narrowing, was several times more common than erosions in our patients and was detected equally well by both PA and image magnification techniques. Soft tissue swelling and juxtaarticular demineralization were better detected by image magnification but are findings that, by themselves, rarely affect therapeutic decisions. Therefore, weighing the benefits of radiographic magnification against its added cost and radiation exposure would, in many clinical situations, favor the continued use of conventional techniques. ACKNOWLEDGMENTS We are indebted to Holly Fossel, Karen Cullen, Mary Scamman, and Holley Eaton for data entry, to Evelyn Cone for secretarial assistance, and to Kristin Mortimer for editorial comments. REFERENCES 1. Brook A, Corbett M: Radiographic changes in early rheumatoid disease. Ann Rheum Dis 36:71-73, 1977 2. Brook A, Fleming A, Corbett M: Relationship of radiological change to clinical outcome in rheumatoid arthritis. Ann Rheum Dis 36:274-275, 1977 3. Martel W, Hayes JT, Duff IF: The pattern of bone erosion in the hand and wrist in rheumatoid arthritis. Radiology 84:204-214, 1965 4. Weissman BN, Sosman JL: The radiology of rheumatoid arthritis. Orthop Clin North Am 6:653-674, 1975 5. Mall JC, Genant HK, Silcox DC, McCarty DJ: The efficacy of fine-detail radiography in the evaluation of patients with rheumatoid arthritis. Radiology 112:37-42, 1974 6. Genant HK, Doi K: High-resolution skeletal radiography: image quality and clinical applications. Curr Probl Diagn Radiol 7:2-62, 1978 7. Genant HK, Doi K, Mall JC, Sickles EA: Direct radiographic magnification for skeletal radiology. Radiology 123:47-55, 1977 8. Genant HK, Doi K , Mall JC: Optical versus radiographic magnification for fine-detail skeletal radiography. Invest Radiol 10:160-172, 1975 9. Doi K, Genant HK, Rossmann K: Comparison of image quality obtained with optical and radiographic magnification techniques in fine-detailed skeletal radiography: effect of object thickness. Radiology 118:189-195, 1976 10. Genant HK: Methods of assessing radiographic change in rheumatoid arthritis. Am J Med 75:35-46, 1983 1 1 . Ishigaki T: First metatarsal-phalangeal joint of gout: macroroentgenographic examination in 6 times magnification. Nippon Acta Rad 335339454, 1973 RADIOGRAPHIC EVALUATION OF RA 75 1 12. Cox DR: Analysis of Binary Data. London, Methuen and Company, 1970 13. Nelder JA, Wedderburn RWM: Generalized linear models. J R Statist Soc 135:370-384, 1972 cal changes in rheumatoid polyarthritis. Br J Radio1 53:63-73, 1980 16. Allander E, Brekkan A, Idbohrn H , Thorsteinsson J, Olafsson 0, Sigfussort N , Sievers K: Is Norgaard’s radiological sign for early rheumatoid arthritis reliable? Scand J Rheumatol 2:161-166, 1973 17. De Smet AA, Martin NL, Fritz SL, Lindsley HB: Radiographic projections for the diaghosis of arthritis of the hands and wrists. Radiology 139577-581, 1981 14. Norgaard F: Earliest roentgenological changes in polyarthritis of the rheumatoid type: rheumatoid arthritis. Radiology 85:325-329, 1965 15. Norgaard F: A follow-up study of the earliest radiologi-
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