<prompt> Investigation of choice in parathyroid pathology isCT ScanGallium scanThallium scanTc Thallium substraction scan  <response>: Presently, Tc - 99m sestamibi is the best available agent for parathyroid scanning. Therefore, Technetium - sestamibi Tc - 99m MIBI is the investigation of choice in the localization of parathyroid tumor.Tc - 99m thallium subtraction scan is the second choice. 