Value Of Ultrasonography In Preoperative Localization Of Insulinoma

Objective To study the blood supply of insulinomas with contrast pulse sequencing(CPS) imaging and the second generation contrast agent (SonoVue).The dynamic contrast enhancement and echogenicity of contrast-enhanced ultrasound (CEUS) were studied in order to localizing the insulinomas accurately. The result was compared with the results of common transabdominal ultrasound and other image study methods. The aim was to evaluate the value of contrast-enhanced ultrasonography in preoperative localization of insulinoma.Methods In this study,19 patients who with insulinomas diagnosed by physicians were examined with CPS imaging after an intravenous administration of SonoVue. All patients were fasting for eight to twelve hours before examinations. At first,2D gray-scale sonography was used to depict the outline and inner echo of pancreas, then transformed to the state of CPS after the best section was selected. CEUS CPS examinations were performed with a low mechanical index of 0.16-0.19. 2.4ml SonoVue was bolus injected intravenously, followed by a flush of 5ml of saline. After injection, the dynamic enhancement course of pancreas was observed, and the abnormal enhanced nodules were searched.Results It was confirmed by pathological report after surgery that 20 insulinomas were resected in 19 patients. Only six tumors were detected by common ultrasound and the sensitivity was 30%.17 tumors were detected by preoperative contrast-enhanced ultrasound and the sensitivity was elevated to 85%.There was statistical difference in the sensitivity between common ultrasound and CEUS (P<0.05). The sensitivity for localizing insulinoma preoperatively by DSA, MRI and CT were 80%,71.42%,66.67%.Compare to the result of CEUS, there were no significant difference in the sensitivity (P>0.05).Conclusions Contrast agent could enhance the signal of blood stream remarkably and reflect the perfusion of tissue in order to improve lesions contrast with tissue. The technique of contrast-enhanced ultrasound is a accurate and convenient way in localization of insulinoma. So the technique could be the first choice in localization diagnosis on insulinomas.