Contrast-enhanced harmonic endoscopic ultrasonography for assessment of lymph node metastases in pancreatobiliary carcinoma

AIM: To assess the usefulness of contrast-enhanced harmonic endoscopic ultrasonography(CH-EUS) for lymph node metastasis in pancreatobiliary carcinoma.METHODS: All patients suspected of pancreatobiliary carcinoma with visible lymph nodes after standard EUS between June, 2009 and January, 2012 were enrolled.In the primary analysis, patients with successful EUSfine needle aspiration(FNA) were included. The lymph nodes were assessed by several standard EUS variables(short and long axis lengths, shape, edge characteristic and echogenicity), color Doppler EUS variable [central intranodal blood vessel(CIV) presence] and CH-EUS variable(heterogeneous/homogeneous enhancement patterns). The diagnostic accuracy relative to EUSFNA was calculated. In the second analysis, N-stage diagnostic accuracy of CH-EUS was compared with EUS-FNA in patients who underwent surgical resection.RESULTS: One hundred and nine patients(143 lymph nodes) fulfilled the criteria. The short axis cutoff ≥ 13 mm predicted malignancy with a sensitivity and specificity of 72% and 85%, respectively. These values were 72% and 63% for the long axis cut-off ≥ 20 mm, 62% and 75% for the round shape variable, 81% and 30% for the sharp edge variable, 66% and 61% for the hypoechogenicity variable, 70% and 72% for the CIV-absent variable, and 83% and 91% for the heterogeneous CH-EUS-enhancement variable, respectively. CH-EUS was more accurate than standard and color Doppler EUS, except the short axis cut-off. Notably, three patients excluded because of EUS-FNA failure were correctly N-staged by CH-EUS.CONCLUSION: CH-EUS complements standard and color Doppler EUS and EUS-FNA for assessment of lymph node metastases.