 This is an open-label positron emission tomographycomputed tomography PETCT study to investigate the diagnostic performance and evaluation efficacy of 68Ga-NOTA-exendin-4 in insulinoma and nesidioblastosis patients. A single dose of 55.5-111 Mega-Becquerel MBq 68Ga-NOTA-exendin-4 will be injected intravenously. Visual and semiquantitative method will be used to assess the PETCT images. 