This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Zollinger Ellision Syndrome, Subject name: Medicine
[{'content': 'Which one of the following is best for localization of zollinger ellison syndrome? \nSelect and explain. \nA. EUS (endoscopic ultrasound), B. Secretin injection test, C. MRI, D. Basal gastric acid output', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Endoscopic ultrasound permits imaging of ZES with high degree of resolution (<5mm). This modality rules out small neoplasms in pancreas. Imaging modalities : EUS>octreoscan>MRI>USG The secretin provocative test is usually positive, with the criterion of a >120-pg/mL increase over the basal level having the highest sensitivity (94%) and specificity (100%).', 'role': 'assistant'}]