OBJECTIVES: The aim of this study was to investigate the changes in various parameters of contrast-enhanced ultrasound (CEUS) before and after treatment in patients with IgG4-related autoimmune pancreatitis (IgG4-AIP), and to identify potential indicators that can assist in evaluating disease activity. METHODS: In this prospective study, we enrolled patients diagnosed with IgG4-AIP from June 2021 to November 2022. Demographic characteristics, clinical features, laboratory tests were recorded. Baseline and follow-up, conventional ultrasound and CEUS were conducted. Additionally, a region of interest (ROI) within lesions, pancreatic head, pancreatic body, and pancreatic tail was taken to draw time-intensity curves (TIC) and parameters of TIC were recorded and analysed. RESULTS: Seventy-three active IgG4-AIP patients were enrolled. Follow-up, a notable decrease in the size of the pancreatic lesion was observed with a reduction in the maximum diameter from 4.3 ± 2.0 cm to 1.7 ± 1.6 cm (p=0.01). The results revealed a statistically significant increase in peak intensity (PI) in the head, body, and tail regions of the pancreas (p<
0.001), along with a significant rise in the area under the curve (AUC) in the tail region of the pancreas (p=0.029) after treatment compared to baseline. In contrast, no statistically significant differences were observed in other parameters of TIC. A significant increase of PI was observed in 12 patients with diffuse IgG4-AIP following treatment. Following treatment, there was a significant increase in PI in the focal area among the 12 patients with focal lesions. CONCLUSIONS: CEUS based on TIC holds great potential for assessing response to treatment in patients with IgG4 AIP.