Ultrasonographic detection, definition and quantification of soft tissue oedema in psoriatic dactylitis

Aim: To define and score finger soft tissue oedema in psoriatic dactylitis by ultrasound. Material and methods: A systematic literature review (SLR) on ultrasound-detected finger soft tissue oedema was performed. Subsequently, based on the SLR, a Delphi survey was developed and circulated among a group of 13 expert sonographers, in order to obtain agreement on detection, definition and scoring of finger oedema by B-mode and power Doppler ultrasound. Agreement was considered achieved when each statement was approved by >= 75% of participants. Results: At the first Delphi round, 91 % agreement was obtained for the scanning technique to adopt, including the most appropriate area to evaluate. At the second round, 76% agreement was achieved on the definition of soft tissue finger oedema. At the third round, 76% agreement was obtained for B-mode and power Doppler scores. The volar aspect of the finger and comparisons with the contralateral side were agreed to be the most appropriate in terms of scanning technique. Agreed ultrasound definition of finger soft tissue oedema was "abnormal hypoechoic/anechoic areas, diffused or localized within the subcutaneous tissue between the epidermidis and the tendon-related anatomic structures (i.e. flexor tendon sheath, peritenonium, tendon pulleys), with local thickening, with or without local abnormal Doppler signal, visualised in two perpendicular planes and not evident on the contralateral side". Semiquantitative (0-3) scores for both B-mode and power Doppler were agreed to be the most appropriate to be used. Conclusion: Our work produced, for the first time, technical indications, definition and scoring for the ultrasound assessment of soft tissue oedema in psoriatic dactylitis.