[Can supplemental imaging with SPECT technique improve the diagnostic value of preoperative Tc-99m-MIBI scintigraphy in primary hyperparathyroidism?].

BACKGROUND: The focus of this retrospective study was to evaluate if the additional use of SPECT improves the diagnostic value of the preoperative Tc-99m-sestamibi scintigraphy combined with sonography in patients presenting with primary hyperparathyroidism.

PATIENTS AND METHODS: 62 patients (43 female, 19 male) were examined by visual analysis of planar Tc-99m-sestamibi scintigraphy, SPECT and ultrasound. 14/62 were suffering from superimposed thyroid disease, 22/62 patients underwent previous neck surgery. 12/62 presented with recurrent hyperthyroidism, in 8/62 cases dystopic parathyroid tissue had been localized. For statistic evaluation these imaging modalities were correlated with the histopathological examinations of the surgical specimens for single use as well as combined use for all patients (group 1) and for the subgroups "histologically confirmed adenoma" (group 2), hyperplastic disease (group 3) "recurrency and/or dystopic parathyroid tissue" (group 4) and "patients presenting with thyroid nodules and/or previous neck surgery" (group 5), respectively.

RESULTS: For single use planar scintigraphy showed the highest sensitivity (72%) followed by SPECT (67%) and ultrasound (58%). The combination of planar imaging with ultrasound achieved 83% whereas the combined use of all three modalities increased the sensitivity up to a maximum of 85%. The combined use of the imaging modalities leads to the following results: The histologically proven parathyroid adenomas (group 2) could be detected by planar scintigraphy and sonography with a sensitivity of 87%, for group 3 the combined use of all three modalities reached 69% sensitivity. Group 4 achieved the highest sensitivity (69%) by means of planar scintigraphy and SPECT, whereas group 5 reached 82% by means of planar scintigraphy and ultrasound.

CONCLUSION: Planar Tc-99m-sestamibi scintigraphy combined with ultrasound is superior regarding to sensitivity and to the costs for the noninvasive preoperative detection in patients presenting with primary hyperparathyroidism. Due to economic reasons the additional use of SPECT might be limited to patients presenting with recurrent hyperparathyroidism or atypically located parathyroid tissue.