Automatic Quantification of Radiographic Wrist Joint Space Width of Patients With Rheumatoid Arthritis.

Objective: Wrist joint space narrowing is a main radiographic outcome of rheumatoid arthritis (RA). Yet, automatic radiographic wrist joint space width (JSW) quantification for RA patients has not been widely investigated. The aim of this paper is to present an automatic method to quantify the JSW of three wrist joints that are least affected by bone overlapping and are frequently involved in RA. These joints are located around the scaphoid bone, viz. the multangular-navicular, capitate-navicular-lunate, and radiocarpal joints. Methods: The joint space around the scaphoid bone is detected by using consecutive searches of separate path segments, where each segment location aids in constraining the subsequent one. For joint margin delineation, first the boundary not affected by X-ray projection is extracted, followed by a backtrace process to obtain the actual joint margin. The accuracy of the quantified JSW is evaluated by comparison with the manually obtained ground truth. Results: Two of the 50 radiographs used for evaluation of the method did not yield a correct path through all three wrist joints. The delineated joint margins of the remaining 48 radiographs were used for JSW quantification. It was found that 90% of the joints had a JSW deviating less than 20% from the mean JSW of manual indications, with the mean JSW error less than 10%. Conclusion: The proposed method is able to automatically quantify the JSW of radiographic wrist joints reliably. SIGNIFICANCE: The proposed method may aid clinical researchers to study the progression of wrist joint damage in RA studies.Objective: Wrist joint space narrowing is a main radiographic outcome of rheumatoid arthritis (RA). Yet, automatic radiographic wrist joint space width (JSW) quantification for RA patients has not been widely investigated. The aim of this paper is to present an automatic method to quantify the JSW of three wrist joints that are least affected by bone overlapping and are frequently involved in RA. These joints are located around the scaphoid bone, viz. the multangular-navicular, capitate-navicular-lunate, and radiocarpal joints. Methods: The joint space around the scaphoid bone is detected by using consecutive searches of separate path segments, where each segment location aids in constraining the subsequent one. For joint margin delineation, first the boundary not affected by X-ray projection is extracted, followed by a backtrace process to obtain the actual joint margin. The accuracy of the quantified JSW is evaluated by comparison with the manually obtained ground truth. Results: Two of the 50 radiographs used for evaluation of the method did not yield a correct path through all three wrist joints. The delineated joint margins of the remaining 48 radiographs were used for JSW quantification. It was found that 90% of the joints had a JSW deviating less than 20% from the mean JSW of manual indications, with the mean JSW error less than 10%. Conclusion: The proposed method is able to automatically quantify the JSW of radiographic wrist joints reliably. SIGNIFICANCE: The proposed method may aid clinical researchers to study the progression of wrist joint damage in RA studies.

Validation of automatic joint space width measurements in hand radiographs in rheumatoid arthritis.

Computerized methods promise quick, objective, and sensitive tools to quantify progression of radiological damage in rheumatoid arthritis (RA). Measurement of joint space width (JSW) in finger and wrist joints with these systems performed comparable to the Sharp-van der Heijde score (SHS). A next step toward clinical use, validation of precision and accuracy in hand joints with minimal damage, is described with a close scrutiny of sources of error. A recently developed system to measure metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints was validated in consecutive hand images of RA patients. To assess the impact of image acquisition, measurements on radiographs from a multicenter trial and from a recent prospective cohort in a single hospital were compared. Precision of the system was tested by comparing the joint space in mm in pairs of subsequent images with a short interval without progression of SHS. In case of incorrect measurements, the source of error was analyzed with a review by human experts. Accuracy was assessed by comparison with reported measurements with other systems. In the two series of radiographs, the system could automatically locate and measure 1003/1088 (92.2%) and 1143/1200 (95.3%) individual joints, respectively. In joints with a normal SHS, the average (SD) size of MCP joints was [Formula: see text] and [Formula: see text] in the two series of radiographs, and of PIP joints [Formula: see text] and [Formula: see text]. The difference in JSW between two serial radiographs with an interval of 6 to 12 months and unchanged SHS was [Formula: see text], indicating very good precision. Errors occurred more often in radiographs from the multicenter cohort than in a more recent series from a single hospital. Detailed analysis of the 55/1125 (4.9%) measurements that had a discrepant paired measurement revealed that variation in the process of image acquisition (exposure in 15% and repositioning in 57%) was a more frequent source of error than incorrect delineation by the software (25%). Various steps in the validation of an automated measurement system for JSW of MCP and PIP joints are described. The use of serial radiographs from different sources, with a short interval and limited damage, is helpful to detect sources of error. Image acquisition, in particular repositioning, is a dominant source of error.

Automated joint space width quantification of hand and wrist joints: a proof of concept study.

OBJECTIVES: To compare as proof of concept the sensitivity to change of automated quantification of radiographic wrist and hand joint space width (JSW) with scoring JSW according to the Sharp/van der Heijde scoring method (SHS) in two strategy groups of a treat-to-target and tight-control early rheumatoid arthritis (RA) study. METHODS: Digital radiographs were assessed for JSW changes of 134 patients of the 236 patients participating in the second Computer Assisted Management in Early Rheumatoid Arthritis trial, of whom both baseline and year 2 radiographs were available (year 1 radiographs n=125). Of those 134 patients, 70 started with methotrexate and prednisone (MTX+Pred) and 64 with MTX and placebo (MTX+Plac). JSW change over 1 and 2 years of the hands and wrists was assessed, applying both the joint space narrowing (JSN) subscore of the SHS by 2 readers and the automated assessment with the JSW quantification software 'JSQ'. For both methods, progression of JSW change of the hand and wrist was analysed using linear mixed modelling (dependent variable 'JSW', factor 'strategy group', covariate 'follow-up time in years', interaction term 'strategy group*follow-up time'; radiographs of baseline, year 1 and year 2 were used). For each method the standardised mean difference (SMD) for the change in JSW from baseline to year 2 between the treatment strategies was obtained using a non-parametric method. RESULTS: Patient characteristics of the current subpopulation were similar to those of the whole study population. JSN of the hand and wrist according to SHS at 2 years was present in 16 vs. 23% in the MTX+Pred group vs. the MTX+Plac group. The mean yearly progression rates of JSW change of the hands and wrists using JSQ were -0.00mm (95% confidence interval (CI) -0.01; 0.01) for MTX+Pred vs. -0.02mm (95%CI -0.03; -0.01) for MTX+Plac, p=0.045, and using SHS JSN they were 0.19 units (95%CI 0.09; 0.30) vs. 0.30 units (95%CI 0.14; 0.45) for MTX+Pred vs. MTX+Plac, p=0.271. The SMD for the change from baseline to year 2 between the treatment strategies was 0.37 for JSQ and 0.13 for SHS JSN. CONCLUSIONS: In this proof of concept study the yearly progression rate of JSW change of hand and wrist joints, according to the automated JSW quantification software package 'JSQ', was higher in the group initiating MTX+Plac than in the group initiating MTX+Pred. A similar trend was seen with the JSN assessment according to the SHS method of the hand and wrist. However, JSN of the hand and wrist according to SHS, the current gold standard to assess radiographic progression, was seen in only about 20%. Therefore, further studies are needed to conclude firmly that JSQ should be incorporated into quantitative scoring of radiographs in RA.

Automatic Quantification of Radiographic Finger Joint Space Width of Patients With Early Rheumatoid Arthritis.

The assessment of joint space width (JSW) on hand X-ray images of patients suffering from rheumatoid arthritis (RA) is a time-consuming task. Manual assessment is semiquantitative and is observer dependent which hinders an accurate evaluation of joint damage, particularly in the early stages. Automated analysis of the JSW is an important step forward since it is observer independent and might improve the assessment sensitivity in the early RA stage. This study proposes a fully automatic method for both joint location and margin detection in RA hand radiographs. The location detection procedure is based on image features of the joint region and is aided by geometric relationship of finger joints. More than 99% of joint locations are detected with an error smaller than 3 mm with respect to the manually indicated gold standard. The joint margins are detected by combining intensity values and spatially constrained intensity derivatives, refined by an active contour model. More than 96% of the joints are successfully delineated. The JSW is calculated over the middle 60% of a landmark-defined joint span. The overall JSW error compared with the ground truth is 6.8%. In conclusion, the proposed method is able to automatically locate the finger joints in RA hand radiographs, and to quantify the JSW of these joints.

Computerised versus conventional methodology of radiographic joint destruction assessment in early rheumatoid arthritis.

OBJECTIVES: To compare computerised and conventional methodology of radiographic joint destruction assessment in early rheumatoid arthritis (RA). METHODS: We investigated the contribution of the 3rd-to-5th carpometacarpal joints (CMC3-5, which are excluded in computerised assessment so far owing to bone overlapping) to total joint space narrowing (JSN) scores in two cohorts of patients with early RA (n=392). Next, we investigated agreement between JSN scoring using single time point individual joint-based method (individual joint of a single time point (IJSTP), reflecting computerised reading) and conventional JSN scoring using the Sharp-van der Heijde (SvdH) method in a cohort of patients with early RA (n=59). We used intraclass correlation coefficients (ICCs), Bland and Altman plots, and linear mixed modelling to analyse differences in progression between two methods. Radiographs were available at baseline, and at 1 and 2 years of follow-up. RESULTS: Of all joints affected by JSN at baseline or JSN progression during 2 years of follow-up, 3.9% and 6.6% concerned CMC3-5. Exclusion of CMC3-5 resulted in a decrease of 1.9-4.6% in JSN progression scores during 2 years of follow-up. The ICCs for JSN progression scores using IJSTP with or without CMC3-5 compared with SvdH were 0.71-0.81 and 0.69-0.78 at 1 and 2 years of follow-up. Signal-to-noise ratios for IJSTP-based and SvdH scoring were 0.51 and 0.58, respectively. The progression rate for each year was not statistically significantly different between two scoring methods (p=0.59 and 0.89). CONCLUSIONS: This study showed that excluding CMC3-5 has limited influence on JSN (progression) scores and showed the feasibility of using IJSTP-based reading for computerised scoring of JSN (progression) in RA.