SCT and gastrin-producing neuroendocrine tumor: The recommendations were based on responses of 59 ENETs centers of Excellence [201], which reported that the biochemical modalities used for gastrinoma diagnosis in the various center included 98% using FSG, 36% using FSG only, 55% using FSG plus gastric pH, FSG plus secretin or calcium stimulation test (7%), and secretin stimulation test only (2%).