Clinicopathological analysis of contrast-enhanced ultrasonography using perflubutane in pancreatic adenocarcinoma

Abstract

The contrast harmonic imaging technique allows visualization of micro bubbles and has facilitated the detection of blood flow on contrast-enhanced ultrasonography (CE-US). In hypovascular tumors such as pancreatic cancer a hypoxic nutrition-deficient environment increases tumor malignancy. In this study, we investigated the relation between CE-US findings, intratumoral microvessel density (MVD), and pathological analysis in pancreatic cancer, and we also investigated the clinicopathological significance of CE-US. The subjects were 16 pancreatic cancer patients who underwent CE-US before surgery. A time-signal intensity curve (TIC) was prepared based on the region of interest (ROI) in the tumor on CE-US, and the signal intensity (SI) was defined as an increase from the value before contrast imaging to the maximum value. Regarding MVD, histological sections were stained with anti-CD34 and α-smooth muscle actin (α-SMA) antibodies, and double stained micro-blood vessels were counted. The correlation between SI and MVD was investigated. In addition, disease-free survival (DFS) was compared between the hypo ( mean SI) SI groups. SI in cancerous lesions was 54.6±42.9 dB (mean±SD), and MVD in cancerous lesions was 12.5±5.02 (mean±SD). A positive correlation was noted between the SI and MVD (r2=0.408, p=0.008). The median DFS were 212 and 606 days in the hypo and hyper SI groups, respectively, showing a significantly shorter DFS in the hypo SI group (P=0.003). No patient died of the primary disease during the follow-up period in the hyper SI group, and a maximum 47-month follow-up was possible. A positive correlation was noted between SI and MVD, indicating that MVD of pancreatic cancer could be evaluated using CE-US. We suggested that CE-US is a useful predictor of patient prognosis after pancreatic cancer surgery.