The complementary roles of fast spin-echo MR imaging and double-phase 99m Tc-sestamibi scintigraphy for localization of hyperfunctioning parathyroid glands.

OBJECTIVE

Our purpose was to evaluate and compare prospectively fast spin-echo MR imaging and double-phase technetium-99m-sestamibi scintigraphy for preoperative localization of hyperfunctioning parathyroid glands in high-risk surgical patients.

SUBJECTS AND METHODS

Twenty-five patients, including 17 with a history of neck surgery, underwent preoperative MR imaging and technetium-99m-sestamibi scintigraphy. Initial interpretation of each study was made independently by two radiologists and then done in combination. At surgery, the location, weight, and dimensions, as well as detailed histopathologic evaluations, of all excised glands were recorded.

RESULTS

All but two patients became normocalcemic after surgery. MR and sestamibi imaging revealed 31 of 37 (84%) and 29 of 37 (79%) of all abnormal glands, respectively. Sensitivities of MR and sestamibi imaging were higher for adenomas (17 of 18 [94%] and 16 of 18 [89%], respectively) than for hyperplastic glands (14 of 19 [74%] and 13 of 19 [68%], respectively). The specificity of sestamibi imaging (94%) exceeded that of MR imaging (75%). All ectopic glands (n = 8) were correctly localized by both techniques. Glands with atypical MR imaging characteristics (isointense or hyperintense to normal thyroid on T1-weighted spin-echo and fast spin-echo images) were more likely to have increased fat, chronic hemorrhage, or sclerosis and fibrosis (p < .05). When MR imaging and sestamibi studies were interpreted together, their sensitivities for adenomas and for hyperplastic glands were 94% (17 of 18) and 84% (16 of 19), respectively. Overall sensitivity of MR imaging and sestamibi studies interpreted together was 89%; overall specificity was 95%.

CONCLUSION

The greater specificity and anatomic coverage of sestamibi scintigraphy coupled with the greater anatomic detail provided by MR imaging and its improved sensitivity over sestamibi imaging in specific patients may justify using both techniques in high-risk surgical patients who have hyperparathyroidism, particularly patients undergoing repeat surgery.