Value of contrast-enhanced ultrasonography in assessing the activity of idiopathic retroperitoneal fibrosis: a prospective study

Abstract

We aimed to evaluate changes in the contrast-enhanced ultrasound (CEUS) parameters in patients with idiopathic retroperitoneal fibrosis (RPF) before and after treatment, and to analyse the value of CEUS to assess RPF activity. We performed a prospective study that included patients with idiopathic RPF who were treated for RPF at our hospital from April 2016 to April 2019. All patients underwent CEUS examination and some of them underwent positron emission tomography/computed tomography (PET/CT) examination simultaneously. CEUS parameters included tube wall and peripheral thickness, arterial wall intensity, and lumen intensity. The changes in CEUS parameters before and after treatment were evaluated, and their correlations with the standardised uptake value (SUVmax), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) were analysed. Thirty-one active idiopathic RPF patients were enrolled, of whom 11 underwent PET/CT examination before treatment. Tube wall and peripheral thickness (r=0.743, p<0.01) and arterial wall intensity (r=0.702, p<0.05) both correlated significantly with SUVmax. Lumen intensity did not correlate significantly with SUVmax (r=0.544, p=0.084). The correlation coefficients between lesion thickness and ESR levels were 0.508 (p=0.037), between lesion thickness and CRP levels were 0.575 (p=0.016). Arterial wall intensity and lumen intensity were not significantly correlated with ESR or CPR levels. Tube wall and peripheral thickness, arterial wall intensity, decreased significantly after treatment (p=0.001), while the lumen intensity was not significantly changed after treatment. Our findings suggest that CEUS, a radiation-free and repeatable detection method, is effective for assessing idiopathic RPF disease activity.