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High frame rate perfusion imaging in rheumatology

Principal investigator:   Rik Vos

High frame rate perfusion imaging in rheumatology

[M. van der Ven, L.L. Van der Velden, J. Luime, J.G. Bosch, J.M.W. Hazes, H.J. Vos, "High-frame rate power Doppler ultrasound is more sensitive than conventional power Doppler in detecting rheumatic vascularisation", Ultrasound in Medicine and Biology;43(9):1868-1879, 2017 ]

Introduction - Early recognition of joint inflammation will increase treatment efficacy in rheumatic arthritis (RA). Yet, conventional power Doppler (PD) ultrasound might not be sufficiently sensitive to detect minor inflammation. We investigated the sensitivity of high-frame rate Doppler, combined with Singular Value Decomposition technique to suppress tissue signals, for microvascular flow in a flow phantom setup and in a proof-of-principle study in healthy controls and in RA patients with different disease activities.

Population - Ten healthy controls and 14 RA patients were included in this proof-of-principle study. To be able to interpret ultrasound results we included RA patients with a broad spectrum of disease activity: i) RA patients in clinical remission (no clinically swollen or tender joints); ii) RA patients who were well controlled (low to medium disease activity, but with clinically swollen and/or tender joints); and iii) RA patients with a clinical flare (high disease activity with clinically swollen and/or tender joints). Disease activity was measured by physical examination of swollen and tender joints, and disease activity score (DAS) in 28 joints was calculated (Prevoo et al. 1995). A clinically swollen joint needed to be confirmed by the patient's treating rheumatologist. Written informed consent was obtained from the participants according to the declaration of Helsinki. The study was approved by the local medical ethics committee of Erasmus MC, University Medical Centre Rotterdam, the Netherlands (MEC-2015-179) using the Verasonics-256 ultrasound research system.

Results - In the flow phantom, minimal detectable flow velocity was a factor three lower with high-frame rate PD than with conventional PD ultrasound. In the proof-of-principle study we detected a positive PD signal in all volunteers, diseased or healthy, with high-frame rate PD ultrasound. We saw a gradual increase of PD signal in RA patients depending on disease activity. In conclusion, high-frame rate Doppler is more sensitive to detect vascularisation than conventional PD ultrasound.

(see pictures below)

Figure: repeat measurements showing the high repeatability of the method.