TC99m MIBI scintigraphy in well-differentiated thyroid carcinoma

To review our experience and assess the role of TC99m MIBI thyroid scintigraphy in patients with well-differentiated thyroid carcinoma.

Cross sectional descriptive study comparing the results of TC99m MIBI and TC99m pertechnetate scintigraphy with histology.

Ga-Rankuwa Hospital, a tertiary referral centre, MEDUNSA, South Africa.

Between October 1998 and January 2000, 63 patients presenting with a single thyroid nodule were included in this study.

All patients included in the study were subjected to fine needle aspiration, thyroid function tests, TC99m pertechnetate and TC99m MIBI scintigraphy. Following surgery all specimens were sent for pathological examination.

The outcome of the study was measured comparing the results of pre-operative TC99m MIBI and TC99m pertechnetate scintigraphy with final histology.

41 of these 63 patients were found to have benign disease and 22 patients had malignant disease. In the malignant group there were 17 females and five males. The age of the patients ranged from 28 years to 85 years in the carcinoma group. Thirteen patients had follicular carcinoma, six patients had papillary carcinoma, two patients had Hurthle cell carcinoma and one patient had medullary carcinoma. TC99m MIBI correctly predicted malignancy in 21/22 patients in contrast with TC99m pertechnetate scintigraphy which diagnosed malignancy in 17/22 patients. The sensitivity of MIBI was 95% and its specificity was found to be 63%. The sensitivity and specificity of TC99m pertechnetate, however, was 77% and 29% respectively.

TC99m MIBI scintigraphy can be used in association with Fine Needle Aspiration (FNA) in the pre-operative evaluation of thyroid carcinoma.