Contrast-enhanced harmonic endoscopic ultrasonography with time-intensity curve analysis for intraductal papillary mucinous neoplasms of the pancreas

Background and study aims: Preoperative diagnosis of the pathological grade of intraductal papillary mucinous neoplasms (IPMNs) is difficult. This study aimed to evaluate the accuracy of contrast-enhanced harmonic endoscopic ultrasonography (CH-EUS) with time - intensity curve analysis in differentiating between low or intermediate grade dysplasia (LGD/IGD) and high grade dysplasia or invasive carcinoma (HGD/invasive carcinoma) in IPMNs and to assess correlation between the time - intensity curve parameters and tumor microvessel density. Patients and methods: Data from 30 patients with resected IPMNs (14 LGD/IGD, 16 HGD/invasive carcinoma) who underwent CH-EUS with time - intensity curve analysis were evaluated retrospectively. Time - intensity curve parameters and the microvessel density of the mural nodule were compared between the HGD/invasive carcinoma and LGD/IGD groups; the diagnostic accuracy of the time - intensity curve parameters was evaluated. Results: The echo intensity change and echo intensity reduction rate of the mural nodule, and the nodule/pancreatic parenchyma contrast ratio were significantly higher in the HGD/invasive carcinoma group than in the LGD/IGD group (P < 0.05); the accuracies of these parameters were 80 %, 86.7 %, and 93.3 %, respectively. The microvessel density of the mural nodule was significantly higher in the HGD/invasive carcinoma group (P = 0.002). There was a strong positive, linear correlation between the echo intensity change of the mural nodule and the microvessel density (r = 0.803, P < 0.001). Conclusions: CH-EUS with time - intensity curve analysis is potentially useful for quantitatively evaluating the blood flow of IPMN microvasculature, and for differentiating between HGD/invasive carcinoma and LGD/IGD.