Ms. Olga Schenk Profile

Olga Schenk

at Univ Twente

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Publications (2)

SPIE Journal Paper | 23 November 2016 Open Access

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

Olga Schenk, Yinghe Huo, Koen Vincken, Mart van de Laar, Ina H. Kuper, Kees C. Slump, Floris P. J. Lafeber, Hein B. Bernelot Moens

JMI, Vol. 3, Issue 04, 044502, (November 2016) https://doi.org/10.1117/12.10.1117/1.JMI.3.4.044502

KEYWORDS: Radiography, Microchannel plates, Image acquisition, Image processing, Error analysis, Medical imaging, Rheumatology, Computing systems, Indium arsenide, Gold

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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 1.7±0.2 and 1.6±0.3 mm in the two series of radiographs, and of PIP joints 1.0±0.2 and 0.9±0.2 mm. The difference in JSW between two serial radiographs with an interval of 6 to 12 months and unchanged SHS was 0.0±0.1 mm, 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.

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Proceedings Article | 24 March 2016 Paper

Segmentation and determination of joint space width in foot radiographs

O. Schenk, D. de Muinck Keizer, H. Bernelot Moens, C. Slump

Proceedings Volume 9785, 97853G (2016) https://doi.org/10.1117/12.2216873

KEYWORDS: Radiography, Bone, Image segmentation, Algorithm development, Visualization, Image analysis, Image processing algorithms and systems, Databases, Rheumatology, CAD systems, Data modeling

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