TC-99M TETROFOSMIN IMAGING IN THYROID-DISEASES - COMPARISON WITH TC-99M-PERTECHNETATE, TL-201 AND TC-99M-METHOXYISOBUTYLISONITRILE SCANS

Technetium-99m tetrofosmin is a lipophilic phosphine used for myocardi al perfusion imaging. Biodistribution studies have shown significant t hyroid uptake of tetrofosmin and preliminary reports have suggested th at tetrofosmin imaging may be of value in patients with thyroid cancer . In this study, tetrofosmin whole-body scintigraphy was performed in 35 patients with evidence of thyroid diseases. All patients underwent laboratory evaluation of thyroid function as well as Tc-99m pertechnet ate scan, thallium-201 (n=16) Tc-99m-methoxyisobutylisonitrile (MIBI) (n=19) whole-body studies. Thyroid images were semi-quantitatively ana lysed by a 4-point score: 0=no significant uptake; 1=uptake increased as compared to background activity, but inferior to normal thyroid tis sue; 2=uptake equal to normal thyroid tissue; 3=uptake superior to nor mal thyroid tissue, Pathology examinations were obtained. A total of 4 1 thyroid nodules were detected, of which 15 were goitre nodules, 13 a denomas and 13 malignant lesions, In goitre nodules, concordant result s of tetrofosmin and pertechnetate uptake (score 1 or 0) were observed in the majority of lesions (87%). In function adenomas (n=10), both t etrofosmin uptake and pertechnetate uptake were score 3. In non-functi on adenomas (n=3), tetrofosmin uptake was score 3, while pertechnetate uptake was score 0, In six malignant lesions, tetrofosmin uptake was score 3, while pertechnetate uptake was score 0; in the other seven le sions, where a prevalence of goitre abnormalities was observed, result s of tetrofosmin and pertechnetate uptake were similar (score 0 or 1). In seven (70%) of the ten patients with malignant nodules, whole-body tetrofosmin images showed increased abnormal uptake in a total of 28 extra-thyroid tumour sites, as subsequently confirmed by other techniq ues. When tetrofosmin images were compared to Tl-201 and Tc-99m-MIBI s cans, concordant results were observed in all cases, In conclusion, te trofosmin imaging may be particularly useful to characterize and stage patients with malignant thyroid nodules; it shows similar results to thallium but provides better image quality. Comparable findings were o bserved between tetrofosmin and MIBI studies, Thus, tetrofosmin may be an alternative to thallium and MIBI in the aforementioned patients.