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Development and validation of SCAISS, a tool for semi-automated quantification of sacroilitis by magnetic resonance in spondyloarthritis


To develop a semi-automated method to quantify inflammation in sacroiliac (SI) joints by measuring bone marrow edema (BME) on MRI. The SCAISS was designed as an image-processing software. Validation followed: (1) three readers evaluated SI images of 23 patients with axial SpA and various levels of BME severity with the SCAISS, and two non-automated methods, SPARCC and Berlin; (2) 20 readers evaluated 12 patients images, also with the three methods; (3) 203 readers evaluated 12 patient images with the Berlin and the SCAISS. Convergent validity, reliability and feasibility were estimated in the first two steps and reliability was confirmed with the third. The interobserver reliability (ICC and 95% CI) in the three observers’ study was similar across methods: SCAISS = 0.770 (0.580–0.889); Berlin = 0.725 (0.537–0.860); and SPARCC = 0.824 (0.671–0.916). In the 20 observers’ study, ICC was: SCAISS = 0.801 (0.653–0.927); Berlin = 0.702 (0.518–0.882); and SPARCC = 0.790 (0.623–0.923). In the 203 observers’ study, ICC were: SCAISS = 0.810 (0.675–0.930), and Berlin = 0.636 (0.458–0.843). SCAISS showed good convergent validity (r with SPARCC = 0.760). Median time (interquartile range) employed in the reading procedure was 28 (27) seconds for the SCAISS, 14 (9) for the Berlin score, and 94 (68) for the SPARCC. The SCAISS permits a valid, reliable, and fast calculation of overall BME lesion at the SI joint on MRI images not dependent on readers’ experience.

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Mireia Moreno (Rheumatology, H. Parc Taulí), Xavier Juanola (Rheumatology, H. Bellvitge), Maite Ventemillas (Radiology, H. Parc Taulí), Victoria Navarro (Rheumatology, H. La Paz), Daniel Bernabeu (Radiology, H. La Paz), Rafael Montero Perez-Barquero (Radiology, H. Reina Sofía de Córdoba), Concha Crespo (Radiology, H. de San Juan de Alicante), Enrique Batlle (Rheumatology, H. de San Juan de Alicante), Carmen Castro Copete (Radiology, H. H. de San Juan de Alicante), Carlos Quiles (Radiology, H. General Universitario de Valencia), Emma Beltrán (Rheumatology, H. del Mar), Fran García Lorente (Rheumatology, H. Universitario de Basurto), Fernando Díez (Radiology, H. Universitario de Basurto), Luis Linares (Rheumatology, H. Virgen de la Arrixaca), Manuel José Moreno Ramos (Rheumatology, H. Virgen de la Arrixaca), Angela Cepero (Radiology, H. H. Virgen de la Arrixaca), Cristina Fernández Carballido (Rheumatology, H. de Elda), Christopher Pack (Radiology, H. de Elda). In addition, a list of the participants of the workshops is presented in Suppl. Material.

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Authors and Affiliations




All authors contributed to the design and conception of study. AB, RA and PZ prepared the selection of patients and images, read the images and commented on problems of data collection, LMM performed the software adaptation and statistical analysis. RA and PZ wrote the draft of the manuscript. The components of the SCAISS Group voluntarily participated in the validation studies by providing the readings. All authors contributed to the manuscript and revised the last version.

Corresponding author

Correspondence to Raquel Almodóvar.

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Conflict of interest

The study was not funded and the software does not have a commercial use. Therefore, the authors declare no competing interests.

Research involving human participants

The study protocol was approved by the hospital Universitario Fundación Alcorcón Ethic Committee (number 16/112, date January 12, 2017) and the study was performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.

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Informed consent was obtained for using patient images.

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Zarco, P., Almodóvar, R., Bueno, Á. et al. Development and validation of SCAISS, a tool for semi-automated quantification of sacroilitis by magnetic resonance in spondyloarthritis. Rheumatol Int 38, 1919–1926 (2018).

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