Possible parathyroid imaging using Ga-67 and other aluminum analogs.

Aluminum has been found to localize in parathyroid adenomas, but it has no isotopes suitable for imaging. Chemical analogs of aluminum were therefore evaluated as potential parathyroid seekers. Uptakes of gallium-67, scandium-46 and lutetium-177 were measured in rat parathyroid, thyroid, cervical muscle, and whole blood, over the time period 30 min to 8 days. Both differential and absolute uptakes of Ga-67 and Sc-46 in the parathyroids are greater than that reported for Se-75 selenomethionine. Uptake of Ga-67 is about 2% of the injected dose per gram of parathyroid tissue at 3-4 days, with a parathyroid-to-thyroid uptake ratio of about 6. Studies indicate possible imaging of adenomas at least as small as those now detected only with invasive methods.