Background Ultrasound (US) B-flow imaging (BFI) is a new technique for vascular imaging, based on US grey scale physics 1. Therefore, Doppler artefacts such as aliasing, blooming and reverberations are not seen. Whether it is an alternative to Doppler for depicting inflammatory flow in the tendon sheath in rheumatoid arthritis patients (RA) is unknown.
Objectives To evaluate US BFI for assessment of inflammatory activity in the tendon sheath compared to grey scale (GS), colour Doppler (CD) US and magnetic resonance imaging (MRI).
Methods Ten RA patients with US-verified tenosynovitis were included. GS, CD and BFI assessment were performed using a GE Logiq E9 US unit with a high frequency linear 6–15 ML probe. BFI settings were adjusted to maximum sensitivity of 50, frequency at 12 MHz and dynamic range at 66. GS frequency was 15 MHz and CD settings according to published recommendations (ref). All settings were identical in all examinations. Axial T1-weighted pre- and post-contrast fat-saturated MR image sets (0.8mm slice thickness) were obtained using a Philips 1T MRI scanner (figure 1). One tendon sheath per patient was scored, in either the wrist or at the metacarpophalangeal joint level. CD, GS and MR images were scored for tenosynovitis 0–3 as proposed by the OMERACT US group and the OMERACT MRI in arthritis working group. BFI was scored peritendiniously as: 0: No flow, 1: Focal flow, 2: Multifocal flow, 3: Diffuse flow. Descriptive statistics were used for comparison of BFI, GS, CD and MRI scores.
Results The mean (SD) score for the patients were 0.89 (0.74), 2.10 (0.74), 2.20 (0.92) and 2.30 (0.95) for BFI, GS, CD, and MRI, respectively. The difference between CD vs GS and MRI was never larger than ±1. The difference between CD and BFI was 1 in 5 patients and ≥2 in 3 patients (table 1).
Conclusions BFI is a new imaging modality for visualization of perfusion. However, the presented results indicate that BFI is less sensitive to detect inflammation in the tendon sheath than CD, GS and MRI in RA patients. Further studies are required, in order to increase image optimization and flow sensitivity, but also to evaluate further use of BFI in diagnosis of inflammatory conditions.
Weskott HP. [B-flow–a new method for detecting blood flow]. Ultraschall in der Medizin (Stuttgart, Germany: 1980) 2000;21(2):59–65.
Disclosure of Interest None declared