Different imaging techniques in localization and diagnosis of insulinoma

Objective To evaluate the application of different imaging techniques in diagnosis and localization of insulinoma. Methods The clinical data of 210 patients with insulinoma who underwent surgical treatment in Chinese PLA General Hospital from January 1985 to May 2014 were retrospectively reviewed. Results The typical "Whipple Triad" was presented in 92.4% (194/210) patients, and their venous blood glucose levels were lower than 2.8 mmol/L. The ratio of insulin to blood glucose was over 0.3 in 90.6%(163/180) patients. The positive rate of insulinoma localization by ultrasonography, CT, MRI, digital subtraction angiography (DSA), endoscopic ultrasonography (EUS) and contrast-enhanced ultrasonography (CEUS) were 33.5%(62/185), 66.0%(128/194), 72.5%(58/80), 94.5%(104/110), 83.2%(109/131) and 96.8%(92/95) respectively. EUS and CEUS had significantly higher positive rate in localizing insulinoma compared to other imaging techniques (χ2=7.48, P=0.00); there was no significant difference between EUS and CEUS(χ2=0.64, P=0.42). Conclusion Compared to other imaging techniques EUS and CEUS are more sensitive in diagnosis and localization of insulinoma; particularly, CEUS as a low-cost and simple method, should be used for preoperative diagnosis of insulinoma. Key words: Insulinoma; Localization diagnosis; Contrast-enhanced ultrasonography