Hyperparathyroidism - How to optimize parathyroid imaging by means of Tc-99m sesta-MIBI scintigraphy and ultrasound?

Background: The aim of this retrospective study was to compare the sensitivity and positive predictive value of technetium-99m-methoxyisobutyl-isonitrile (sesta-MIBI) scintigraphy and sonography in single and combined use for the detection of parathyroid adenomas in patients presenting with primary hyperparathyroidism. We also examined the value of single-photon-emission computed tomography (SPECT) and ultrasound in improving the diagnostic value of preoperative planar Tc-99m-Sesta-MIBI scintigraphy. Patients and Methods: In 84 consecutive patients with biochemically proven hyperparathyroidism, Tc-99m-sesta-MIBI and sonographic imaging were retrospectively reviewed by 2 experienced physicians. All patients were studied with planar Tc-99m-sesta-MIBI scintigraphy, SPECT and sonography. The results were correlated with the histopathological studies of the surgical specimens. Results: Sixteen of 84 patients had superimposed thyroid disease, and 25 of 84 had previous neck surgery. Fifteen of 84 had recurrent hyperparathyroidism, in 12 of 84 cases, hyperparathyroidism was due to ectopic parathyroid tissue. As a single modality, planar scintigraphy showed the highest sensitivity (76%) followed by SPECT (71%) and ultrasound (59%). The combination of sesta-MIBI and sonography had a sensitivity of 85% while the combination of all 3 modalities had a sensitivity of 86%. For the detection of histologically proven parathyroid adenomas, the sensitivity and positive predictive value increased to 93% and 100%, respectively, if only 1 of the tests needed to be positive. Conclusion: Tc-99m-sesta-MIBI scintigraphy combined with sonography is superior in sensitivity and positive predictive value to the other single use of the tests. The combination of tests provided a substantial increase in sensitivity and positive predictive value.