Solitary autonomous thyroid nodules: comparison of fluorescent and pertechnetate imaging

Twelve patients with solitary autonomous thyroid nodules were scanned with [99mTc] pertechnetate and by fluorescent imaging. Nodular dimensions were essentially identical on the two types of scans, but the relative scan densities in the nodular versus extranodular areas demonstrated striking differences. In 11 of the 12 patients, the ratio of nodular-to-extranodular radiotracer accumulation was significantly higher than the ratio of nodular-to-extranodular iodine content. In two patients with no demonstrable extranodular radiotracer accumulation by initial pertechnetate scan, extra-nodular tissue was demonstrated by fluorescent imaging. In such cases, fluorescent scanning may eliminate the need for a second radionuclide scan following TSH stimulation to visualize the extranodular tissue. Fluorescent scanning offers a unique new method for aiding the evaluation of patients with suspected autonomous nodules, and can facilitate the diagnosis in some cases. The maintenance of relatively uniform iodine concentration between nodular and extranodular tissues is an intriguing finding that bears further investigation.