TECHNETIUM99M-SESTAMIBI SCANNING BEFORE INITIAL NECK EXPLORATION IN PATIENTS WITH PRIMARY HYPERPARATHYROIDISM

Technetium99m(Tc) sestamibi (mibi) has been proposed as an alternative to the standard radionuclide imaging technique of thallium 201 chloride-Tc-99m pertechnetate subtraction scan (TTS) in patients with primary hyperparathyroidism. In the present study, mibi was evaluated as an alternative to TTS in 37 patients who had either mibi-Tc-99m pertechnetate subtraction scans, mibi-iodine123 (I) subtraction scans or mibi single isotope washout scans. There were 30 females and 7 males with an average age of 57 years (range, 27-78 years). Parathyroid adenomas were found in 35 patients and hyperplasia in 2. Twenty-eight mibi scans were positive and 25 of these correctly localized the parathyroid abnormality for a sensitivity of 68% (25 of 37) and a positive predictive value of 89% (25 of 28). There were 3 false-positives (8%) and 9 false-negatives (25%). The scan was not helpful in either patient with parathyroid gland hyperplasia. Mibi-I-123 substraction was the most accurate scan and was diagnostic clinically in all 7 patients studied. Mibi scans were significantly more likely to identify inferior rather than superior adenomas (P = 0.01). Twenty-seven of the 37 patients also had a TTS which was correct in only 37% of cases while the mibi scan was correct in 68% (P = 0.02). However, routine use of nuclear scanning with mibi was still not supported by these data. Further clinical evaluation of various techniques may improve accuracy. Since mibi was significantly more accurate than TTS, it should be considered preferentially when radionuclide imaging is used in patients with recurrent hyperparathyroidism.