<prompt> Which one of the following is best for localization of zollinger ellison syndrome?EUS endoscopic ultrasoundSecretin injection testMRIBasal gastric acid output  <response>: Endoscopic ultrasound permits imaging of ZES with high degree of resolution 5mm. This modality rules out small neoplasms in pancreas. Imaging modalities : EUSoctreoscanMRIUSG The secretin provocative test is usually positive, with the criterion of a 120-pgmL increase over the basal level having the highest sensitivity 94 and specificity 100. 