Rheumatoid Arthritis: Langs G

Kubassova O, Boesen M, Peloschek P, Langs G, Cimmino MA, Bliddal H, Torp-Pedersen S. · Image Analysis Ltd., University of Leeds, 5-7 Cromer Terrace, Leeds, West Yorkshire, UK. · Ann N Y Acad Sci. · Pubmed #19250239 No free full text.

Abstract: Traditional imaging, represented by radiographs, provides a very concise description of anatomical pathology of bony structures. Both degenerative and inflammatory joint diseases are characterized by progressive joint destruction, and valid, reproducible measures of disease impact are available. Much effort has been expended to develop scoring systems for joint destruction in both osteoarthritis and rheumatoid arthritis, and the most common internationally accepted semiobjective scores are presented. The anatomical pathology mirrors the past activity of the disease, and advanced imaging gives an impression of the actual disease processes, which subsequently lead to the damage. Such information is required to facilitate the development of efficient therapy against arthritis. Newer technology, exemplified by MRI and ultrasound Doppler, supplements images of structural change with functional data of ongoing disease activity. This chapter focuses on the possibilities for quantification of images in MRI and ultrasound, in which postcontrast enhancement and Doppler information, respectively, are of special interest for the evaluation of the inflammatory changes of arthritis. To save time and eliminate human bias, automation is mandatory. In ultrasound, semiautomatic evaluations are coming that allow for a real-time, reproducible estimate of disease activity. With MRI fully automated algorithms have been developed for processing of data of bony structures, cartilage, and soft tissue, and are currently being implemented into everyday clinical practice.

Peloschek P, Langs G, Valentinitsch A, Bubale M, Schlager T, Müller-Mang C, Kainberger F. · Klinik für Radiodiagnostik, Medizinische Universität Wien, Währinger Gürtel 18-20, 1090 Wien, Osterreich. · Radiologe. · Pubmed #16715225 No free full text.

Abstract: The need of clinical sciences to measure therapy effects on chronic illness led to development, evaluation, and publication of several radiological methods to monitor disease progression of rheumatic diseases. This review article explains the basics and background of scoring and measurement. The radiologist thus learns to report more compactly and to communicate the results more specifically.

Langs G, Peloschek P, Bischof H, Kainberger F. · Applied Mathematics and Systems Laboratory (MAS), Ecole Centrale de Paris, Grande Voie des Vignes, 92 295 Chatenay-Malabry, France. · IEEE Trans Med Imaging. · Pubmed #19116197 No free full text.

Abstract: Rheumatoid arthritis (RA) is a chronic disease that affects and potentially destroys the joints of the appendicular skeleton. The precise and reproducible quantification of the progression of joint space narrowing and the erosive bone destructions caused by RA is crucial during treatment and in imaging biomarkers in clinical trials. Current manual scoring methods exhibit high interreader variability, even after intensive training, and thus, impede the efficient monitoring of the disease. We propose a fully automatic quantitative assessment of the radiographic changes that result from RA, to increase the accuracy, reproducibility, and speed of image interpretation. Initial joint location estimates are obtained by local linear mappings based on texture features. Bone contours are delineated by active shape models comprised of statistical models of bone shape and local texture. These models are refined by snakes which increase the accuracy and allow for a fitting of pathological deviations from the training population. The method then measures joint space widths and detects erosions on the bone contour. Joint space widths are measured with a coefficient of variation of 2%-7% for repeated measurements and erosion detection exhibits an area under the receiver operating characteristic (ROC) curve of 0.89. Model landmarks serve as a reference system along the contour. These landmarks enable the definition of joint regions and more specific follow-up monitoring. The automatic quantification allows for a remote analysis, relevant for multicenter clinical trials, and reduces the workload of clinical experts since parts of the process can be managed by nonexpert personnel.

Lukas C, Sharp JT, Angwin J, Boers M, Duryea J, Hall JR, Kauffman JA, Landewé R, Langs G, Bernelot Moens HJ, Peloschek P, van der Heijde D. · University of Maastricht, Maastricht, The Netherlands. · J Rheumatol. · Pubmed #18597408 No free full text.

Abstract: OBJECTIVE: Comparison of performances of 5 (semi)automated methods in measuring joint space width (JSW) in rheumatoid arthritis. METHODS: Change in JSW was determined by 5 measurement methods on 4 radiographs per patient from 107 patients included in the COBRA trial (comparing sulfasalazine alone or in combination with methotrexate and corticosteroids). For each method the number of patients with sufficient available results was assessed (efficiency). An independent repeated measurement was carried out on a random sample of 30 patients' baseline and 1-year radiographs, to evaluate within-method reliability of change scores. Discriminatory ability (DA) of the measurement methods (between the 2 treatment arms) was compared with the DA of the Sharp-van der Heijde score (SHS) and its 2 components (erosion and JSW scores). RESULTS: The overall success rate varied widely between methods. Applying the chosen threshold of a minimum of 50% available joints with a change score per patient resulted in a success rate > 92% in 4/5 methods. Repeatability of measurements was good for most methods (intraclass correlation coefficient > or = 0.80 in 4/5 methods). Almost all measurement methods in 3 followup periods (12/14) showed a lower mean loss of JSW in patients from the intensive treatment group, although this was rarely statistically significant, confirming the known difference in structural damage. JSW as measured by the (semi)automated systems often showed higher DA than the JSW score of the SHS, but was lower than the total SHS and erosion scores. CONCLUSION: Although efficiency of the methods should be improved further, results already show good reliability and encouraging DA of most methods. Optimal information may be obtained with a combination of scoring of erosions and (semi)automated measurement of JSW.

Peloschek P, Langs G, Weber M, Sailer J, Reisegger M, Imhof H, Bischof H, Kainberger F. · Department of Diagnostic Radiology, Medical University of Vienna, Vienna, Austria. · Radiology. · Pubmed #17951347 links to  free full text

Abstract: This ethics committee-approved pilot study was performed with informed consent. A Web-based service that was developed for automated measurement of joint space and automatic analysis of radiographs was tested prospectively. A total of 160 metacarpophalangeal joint spaces were measured in 20 patients (average age, 48 years; age range, 18-89 years; 16 women) suspected of having rheumatoid arthritis or osteoarthritis. The technical success rate was 93%. The smallest detectable difference in repeated automatic joint space width measurements varied from 0.08 to 0.31 mm, and the coefficient of variation was 2%-7%. Compared with the reference standard (interactive segmentation of the joint space widths) measurements, results were within a mean error of 0.19-0.40 mm. The proposed Web-based service enables reproducible joint space measurements to be obtained in metacarpophalangeal joints with moderate erosive and osteophytic disease.

Langs G, Peloschek P, Bischof H, Kainberger F. · MAS, Applied Mathematics and Systems Laboratory, Chatenay-Malabry, France. · Acad Radiol. · Pubmed #17889335 No free full text.

Abstract: RATIONALE AND OBJECTIVES: A method for the automatic detection and the visualization of erosions caused by rheumatoid arthritis is investigated. Erosion-enhanced viewing is a contribution to the computer-aided diagnosis of rheumatoid arthritis. It supports the clinician by providing the automatic marking of erosions and the visualization of any deviations from intact anatomy for a concise reviewing interface. MATERIALS AND METHODS: A generative appearance model is used to capture the variability of intact bone and erosions. The algorithm marks erosions on hand radiographs using this model, and visualizes these erosions with the help of the residual appearance error after fitting the model built from intact bone texture. The algorithm was evaluated on 17 hand radiographs. The standard of reference was an annotation of the erosions by a musculoskeletal radiologist. RESULTS: Detection results from the algorithm are reported for a set of 17 radiographs of moderately diseased hands. With a specificity of 84%, the detection of unequivocal erosions achieved a sensitivity of 85%. A receiver operating characteristic analysis yields an area under the curve of 0.92. The visualization provided a clear representation of the erosions as determined by two musculoskeletal radiologists. CONCLUSION: The automatic spotting of erosions provides promising results, and the visualization of the deviation from healthy anatomy aids clinicians in the evaluation of the erosions and in the reviewing of automatic detection results.