Initial planar images take about 40 minutes. In addition, whole body images can be obtained which may add 40 minutes to the procedure. Somatostatin is an endogenous neuropeptide that acts as a regulator of growth hormone secretion.
Neuroendocrine tumors contain a high density of somatostatin receptors.
OctreoScan, a radiolabeled form of the somatostatin analog octreotide, shares the same binding site as naturally occurring somatostatin which makes it a sensitive indicator for somatostatin receptor-bearing neuroendocrine tumors. Since the concentration of receptors on tumors may vary, the sensitivity of OctreoScan may vary among tumor types.