Objective Contrast‐enhanced ultrasound offers numerous potential applications in diagnostic and interventional radiology. However, systematic studies on the status of clinical studies are limited. Hence, the aim of this study was to analyze the characteristics of registered contrast‐enhanced ultrasound studies on ClinicalTrials.gov and identify features associated with early discontinuation and results reporting. Methods A data set containing all contrast‐enhanced ultrasound clinical studies from ClinicalTrials.gov registered was downloaded. Then, a cross‐sectional descriptive study of clinical contrast‐enhanced ultrasound studies was conducted. Cox and logistic regression of early discontinuation and reported results, respectively, were also performed. Results A total of 225 studies were identified; 174 were interventional and 51 were observational. Regarding the outcomes measure, 175 (77.78%) were diagnosis‐oriented, and the remaining 50 (22.22%) were interventional radiology studies. The most common regions of interest were abdominal (56%), superficial (14.22%), or vascular (7.11%) organs. As of the contrast agents, SonoVue/Lumason (39.11%) was most frequently used, followed by Definity (20.89%) and Sonazoid (8.89%). Of all contrast‐enhanced ultrasound studies, 32 (14.22%) were discontinued early, and 29 (12.89%) completed studies reported their results. Cox regression analysis revealed that a large sample size and US registration were factors reducing early discontinuation risk. Among completed studies, factors associated with reported results were industry funding and US registration. Conclusion The findings suggest that the number of contrast‐enhanced ultrasound studies has grown over time, but is still small. Developing new advancements in contrast‐enhanced ultrasound will require a concerted effort to increase the quality and quantity of clinical studies in this field.

Background: Patients with mass-forming pancreatitis (MFP) or pancreatic ductal adenocarcinoma (PDAC) presented similar clinical symptoms, but required different treatment approaches and had different survival outcomes. This meta-analysis aimed to compare the diagnostic performance of contrast-enhanced ultrasound (CEUS) and contrast-enhanced computed tomography (CECT) in differentiating MFP from PDAC. Methods: A literature search was performed in the PubMed, EMBASE (Ovid), Cochrane Library (CENTRAL), China National Knowledge Infrastructure (CNKI), Weipu (VIP), and WanFang databases to identify original studies published from inception to August 20, 2021. Studies reporting the diagnostic performances of CEUS and CECT for differentiating MFP from PDAC were included. The meta-analysis was performed with Stata 15.0 software. The outcomes included the pooled sensitivity, specificity, positive likelihood ratio (+LR), negative likelihood ratio (ÀLR), diagnostic odds ratio (DOR), and summary receiver operating characteristic (SROC) curves of CEUS and CECT. Meta-regression was conducted to investigate heterogeneity. Bayesian network meta-analysis was conducted to indirectly compare the overall diagnostic performance. Results: Twenty-six studies with 2115 pancreatic masses were included. The pooled sensitivity and specificity of CEUS for MFP were 82% (95% confidence interval [CI], 73%-88%; I 2 = 0.00%) and 95% (95% CI, 90%-97%; I 2 = 63.44%), respectively; the overall +LR, ÀLR, and DOR values were 15.12 (95% CI, 7.61-30.01), 0.19 (95% CI, 0.13-0.29), and 78.91 (95% CI, 30.94-201.27), respectively; and the area under the SROC curve (AUC) was 0.90 (95% CI, 0.87-92). However, the overall sensitivity and specificity of CECT were 81% (95% CI, 75-85%; I 2 = 66.37%) and 94% (95% CI, 90-96%; I 2 = 74.87%); the overall +LR, ÀLR, and DOR values were 12.91 (95% CI, 0.21 (95% CI, and 62.53 (95% CI,, respectively; and, the SROC AUC was 0.92 (95% CI, 0.90-0.94). The overall diagnostic accuracy of CEUS was comparable to that of CECT for the differential diagnosis of MFP and PDAC (relative DOR 1.26, 95% CI [0.42-3.83], P > 0.05). Conclusions: CEUS and CECT have comparable diagnostic performance for differentiating MFP from PDAC, and should be considered as mutually complementary diagnostic tools for suspected focal pancreatic lesions.