A Preliminary Study on Contrast Enhanced Ultrasound Characteristics of Solid Pseudopapillary Neoplasms and Pancreatoblastoma in Children

<b>Objective:</b> Solid pseudopapillary neoplasms (SPN) and pancreatoblastoma (PB) have a low overall incidence but represent the most common pancreatic tumors in childhood. Currently, there is a lack of systematic descriptions of contrast-enhanced ultrasound (CEUS) features for these two tumors in pediatric populations. This study aims to retrospectively analyze and compare the CEUS characteristics of SPN and PB to explore key imaging differentiation points. <b>Methods:</b> This retrospective study collected data on 22 patients with solid pseudopapillary neoplasms and pancreatic blastomas of the pancreas who were pathologically diagnosed at a children's hospital between September 2019 and May 2025. The ultrasound contrast-enhanced imaging findings for both tumor types were summarized and analyzed. Two physicians with different levels of experience performed qualitative analysis of the contrast-enhanced images, while quantitative analysis was conducted using time-intensity curve (TIC) analysis software. <b>Results:</b> This study included a total of 22 pediatric patients (19 with SPN and 3 with PB). Significant differences existed between the two groups in age (13.51 years vs. 2.94 years) and Ki-67 index (5.00% vs. 30.00%). Qualitative analysis revealed high heterogeneity in SPN enhancement patterns, with capsular enhancement with cystic components being the most common (42.11%). All PBs (100%) consistently demonstrated the "disorganized nourishing vessels" sign. Quantitative analysis revealed that PBs exhibited numerically higher IMAX values (179.84% vs. 60.56%) and faster WoR trends (773.88 vs. 275.38). Inter-observer consistency analysis supported measurement reliability (key parameters ICC > 0.80). <b>Conclusions:</b> This preliminary study indicates differences in CEUS characteristics between pediatric SPN and PB; PB tends to exhibit rapid, high enhancement with chaotic feeding vessels and rapid washout, whereas SPN more commonly presents with moderate, slow enhancement patterns, often accompanied by features associated with cystic components. These findings provide new hemodynamic clues for their imaging differentiation. Given the extremely small sample size of PB cases, the above conclusions should be regarded as preliminary hypotheses awaiting validation in future large-scale studies.