APOB and bile duct papillary neoplasm: Plasma Lp (a), Lp-PLA2, apoA, and apoB levels were measured; intraplaque angiogenesis (IPN) scores were examined by contrast-enhanced ultrasound (CEUS) to assess IPN grade in patients; and Pearson correlation was used to analyze the relationship between plasma Lp (a) and Lp-PLA2 levels and plaque characteristics and angiogenesis.