Contrast-enhanced harmonic endoscopic ultrasonography (EUS)-guided tissue acquisition significantly improves diagnostic yield for small liver metastases derived from pancreatic cancer: a prospective study.

BACKGROUND AND AIMS: We aimed to clarify the value of Contrast-enhanced harmonic EUS-guided tissue acquisition (C-EUS-TA) for pathological confirmation of liver metastases, particularly small metastases, derived from pancreatic cancer.

METHODS

Fundamental B-mode EUS (B-EUS) and contrast-enhanced EUS (C-EUS) were compared in detection rates of liver metastases in patients with pancreatic cancer. We also assessed the ability of C-EUS-TA for the sensitivity, specificity, and accuracy of the pathological diagnosis of those liver metastases, and compared those values according to the size of the liver metastases (≤5 mm, 5 mm < size ≤10 mm, and size >10 mm in diameter).

RESULTS

The accuracy of C-EUS for detection of liver metastases was significantly higher than that of B-EUS (91.3 % vs. 71.0 %, p = 0.001). In particular, the diagnostic accuracy of C-EUS for small liver metastases (≤5 mm in diameter) was significantly higher than that of B-EUS (93.9 % vs. 66.7 %, p = 0.016). The overall accuracy of C-EUS-TA for pathological diagnosis of liver metastases was 95.2 %. Interestingly, there was no significant difference in the accuracy of C-EUS-TA among the three lesions sizes (≤5 mm: 90.0 %, 5 mm < size ≤10 mm: 100 %, and size >10 mm in diameter: 95.5 %).

CONCLUSION

The present study demonstrates the usefulness and high accuracy of C-EUS-TA for diagnosis of suspected liver metastases, particularly small lesions measuring ≤5 mm. Thus, when confirmation of small liver metastases using conventional imaging is difficult, C-EUS-TA may be useful for histological diagnosis.