Which of the following is the preoperative imaging study of choice for gastrinoma?
A. CT scanCT will detect most lesions >lcm in size and magnetic resonance imaging (MRI) is comparable. Endoscopic ultrasound (EUS) is more sensitive than these other noninvasive imaging tests, but it still misses many of the smaller lesions, and may confuse normal lymph nodes for gastrinomas. Currently, the preoperative imaging study of choice for gastrinoma is somatostatin-receptor scintigraphy (the octreotide scan). When the pretest probability of gastrinoma is high, the sensitivity and specificity of this modality approach 100%. Gastrinoma cells contain type II somatostatin receptors that bind the indium-labeled somatostatin analogue (octreotide) with high affinity, making imaging with a gamma camera possible. Currently, angiographic localization studies are infrequently performed for gastrinoma.