Usefulness of Detective Flow Imaging EUS in Intra-Abdominal Hypervascular Tumors

: Background/Objectives: Although contrast-enhanced endoscopic ultrasound (CH-EUS) plays an important role in the ultrasound imaging-based diagnosis of intra-abdominal hypervascular tumors, detective flow imaging EUS (DFI-EUS), which can detect micro-blood flow without using a contrast agent, has recently emerged. In this study, we investigated the usefulness of DFI-EUS for detecting intra-abdominal hypervascular tumors. Methods: Thirteen patients with intra-abdominal hypervascular tumors detected on contrast-enhanced computed tomography who underwent DFI-EUS and CH-EUS were included. The lesions were classified into non-enhancement, hypo-enhancement, iso-enhancement, and hyper-enhancement patterns. Vascular structural patterns were classified as non-enhancement, homogeneous or heterogeneous enhancement. On DFI-EUS, patients who showed heterogeneous enhancement were evaluated for the presence or absence of dendritic and peritumoral capsule-like structures. Contrast patterns, vascular structure patterns, and detection capabilities of DFI-EUS and CH-EUS were examined. Results: The final diagnoses were pancreatic neuroendocrine neoplasm in 10 patients (76.9%), gastrointestinal neuroendocrine neoplasm in one patient (7.6%), gastrointestinal stromal tumor in one patient (7.6%), and metastatic pancreatic tumor in one patient (7.6%). The contrast patterns (DFI-EUS vs. CH-EUS) were non-enhancement in 7.7% vs. 0%, iso-enhancement in 15.3% vs. 23.0%, and hyper-enhancement in 76.9% vs. 76.9%. The vascular structure patterns (DFI-EUS vs. CH-EUS) showed a homogeneous enhancement of 0% vs. 100% and a heterogeneous enhancement of 92% vs. 0%. Patients with heterogeneous enhancement on DFI-EUS showed a dendritic structure in 91.6% and capsule-like structures in 75.0% of patients. Conclusions: DFI-EUS and CH-EUS showed comparable iso-enhancement or hyper-enhancement patterns. In contrast, DFI-EUS revealed the characteristic heterogeneous patterns of dendritic and capsular-like vascular structures.