UTILITY OF TC-99M-SESTAMIBI SCINTIGRAPHY AS A FIRST-LINE IMAGING PROCEDURE IN THE PREOPERATIVE EVALUATION OF HYPERPARATHYROIDISM

OBJECTIVE The use of preoperative imaging in patients with hyperparathyroidism remains controversial. Many of the available techniques are insufficiently sensitive and specific to justify their routine use. We have evaluated the sensitivity and specificity of Tc-99m-sestamibi scintigraphy in the management of patients with different forms of hyperparathyroidism. DESIGN Preoperative imaging evaluation was carried out by scintigraphic detection of pathological parathyroid glands using Tc-99m-sestamibi as a radiotracer; confirmation of scan findings was obtained surgically. PATIENTS A group of 25 patients with primary (n = 21) or secondary (n = 4) hyperparathyroidism were studied. All were considered for surgical treatment. MEASUREMENTS In all cases parathyroid imaging was carried out by Tc-99m-sestamibi scintigraphy together with at least one other imaging technique which included CT-scan, ultrasonography, MRI or (TI)-T-201/(TC)-T-99m subtraction scintigraphy. Blood tests included measurements of total calcium and PTH. RESULTS Tc-99m-sestamibi scintigraphy correctly localized 20 out of 21 adenomas, giving a sensitivity of 95.2%, markedly higher than that obtained with the other imaging techniques (ultrasonography 75%, (TI)-T-201/(TC)-T-99m subtraction scintigraphy 57.1%, CT-scan 41.7% and MRI 33%). Of a total of 17 glands identified surgically as hyperplastic and confirmed by pathological examination, Tc-99m-sestamibi scintigraphy showed a positive image in 10, corresponding always to the larger abnormal glands (sensitivity 58.8%, higher than that observed with the other techniques). No false positive images were obtained with Tc-99m-sestamibi. All the ectopic adenomas (n = 3) were identified preoperatively, which contributed significantly to the surgical approach. CONCLUSION In patients with hyperparathyroidism, Tc-99m-sestamibi scintigraphy may be used as the single imaging technique as it shows a very high sensitivity and specificity in the preoperative localization of pathological parathyroid glands; the benefit of localizing parathyroid tissue prior to surgery in cases of ectopic adenomas clearly indicates that when an imaging procedure is required, this technique may be of great help in the management of hyperparathyroidism.