ADVANTAGES OF SPECT IN TECHNETIUM-99M-SESTAMIBI PARATHYROID SCINTIGRAPHY

We demonstrate several advantages of SPECT in parathyroid scintigraphy . Methods: Forty-four parathyroid Tc-99m-MIBI scintigrams were obtaine d before surgery in 43 patients suffering from hyperparathyroidism. Fo r each patient, we obtained dynamic views and planar and SPECT images of the neck and thorax. For 15 patients, we also acquired a delayed st atic view of the neck 2 hr after tracer injection. Abnormal thyroid-ar ea glands were detected with factor analysis of dynamic structure (FAD S) of the initial dynamic acquisition. In the 15 patients with delayed views of the neck, we compared FADS and the double-phase study result s to detect glands in the thyroid uptake area. Glands outside the thyr oid area were demonstrated on planar views. The location of enlarged g lands was more precisely defined on the tomographic slices. The anatom ic and histologic findings and the evolution of hypercalcemia after su rgery were taken as reference. Results: Sixty-four abnormal glands wer e found during surgery, including 39 observed in patients who underwen t reoperation for persistent or recurrent hyperparathyroidism. Twenty- two of these glands were in an abnormal location, including 10 in the mediastinum. SPECT allowed the detection of three glands not demonstra ted on planar views or FADS. Fifty-eight glands were correctly localiz ed scintigraphically, including 34 in patients who underwent reoperati on. Therefore, SPECT raised the sensitivity from 86% to 90.5% and from 79.5% to 87% in the reoperated patients. Tracer uptake in the low med iastinal area was better analyzed on tomographic slices than on planar views. Only seven false-positive results were depicted by planar view s or FADS; none were depicted on SPECT. Conclusion: A combination of F ADS and SPECT permits detection of small glands, even in a posterior l ocation, inside or outside the thyroid area. This scintigraphic method enables the surgeon to define more precisely details about the locati on of the enlarged gland and contributes to improved parathyroid surge ry.