title: Pixel-based approach to assess contrast-enhanced ultrasound kinetics parameters for differential diagnosis of rheumatoid arthritis.
abstract: Inflammatory rheumatic diseases are the leading causes of disability and constitute a frequent medical disorder, leading to inability to work, high comorbidity, and increased mortality. The standard for diagnosing and differentiating arthritis is based on clinical examination, laboratory exams, and imaging findings, such as synovitis, bone edema, or joint erosions. Contrast-enhanced ultrasound (CEUS) examination of the small joints is emerging as a sensitive tool for assessing vascularization and disease activity. Quantitative assessment is mostly performed at the region of interest level, where the mean intensity curve is fitted with an exponential function. We showed that using a more physiologically motivated perfusion curve, and by estimating the kinetic parameters separately pixel by pixel, the quantitative information gathered is able to more effectively characterize the different perfusion patterns. In particular, we demonstrated that a random forest classifier based on pixelwise quantification of the kinetic contrast agent perfusion features can discriminate rheumatoid arthritis from different arthritis forms (psoriatic arthritis, spondyloarthritis, and arthritis in connective tissue disease) with an average accuracy of 97%. On the contrary, clinical evaluation (DAS28), semiquantitative CEUS assessment, serological markers, or region-based parameters do not allow such a high diagnostic accuracy.
authors.affiliation: University of Padova , Department of Information Engineering, G. Gradenigo 6/A, Padova 35131, Italy.
authors.forename: Gaia
authors.initials: G
authors.lastname: Rizzo
authors.affiliation: General Hospital of Bolzano , Rheumatology Unit, Via Lorenz Boehler 5, Bolzano 39100, Italy.
authors.forename: Bernd
authors.initials: B
authors.lastname: Raffeiner
authors.affiliation: University of Padova , Department of Medicine, Via Giustiniani 2, Padova 35128, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Coran
authors.affiliation: Nursing Home Giovanni XXIII , Via Giovanni XXIII 7, Monastier di Treviso (TV) 31050, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Ciprian
authors.affiliation: University of Padova , Department of Medicine, Via Giustiniani 2, Padova 35128, Italy.
authors.forename: Ugo
authors.initials: U
authors.lastname: Fiocco
authors.affiliation: University of Padova , Department of Medicine, Via Giustiniani 2, Padova 35128, Italy.
authors.forename: Costantino
authors.initials: C
authors.lastname: Botsios
authors.affiliation: University of Padova , Department of Medicine, Via Giustiniani 2, Padova 35128, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Stramare
authors.affiliation: University of Padova , Department of Information Engineering, G. Gradenigo 6/A, Padova 35131, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Grisan
keywords: arthritis; contrast enhanced ultrasound; kinetics analysis; parameter estimation; perfusion analysis