Clinical importance of technetium-99m-methoxyisobutylisonitrile (MIBI) scintigraphy in differentiated thyroid carcinoma patients with elevated thyroglobulin levels and negative I-131 scanning results.
OBJECTIVE
The aim of this study was to evaluate the potential contribution of Tc-99m-MIBI scintigraphy to the follow-up of patients with differentiated thyroid carcinoma, who had elevated Tg levels and negative I-131 whole-body scan results.


METHODS
In this retrospective study, we evaluated 28 patients with differentiated thyroid carcinoma, who had total or near total thyroidectomy followed by an ablative dose of I-131 at various time intervals (15 women, 13 men; mean age 43 +/- 17 years). All patients were treated with T4 suppression. After a mean follow-up period of 6.1 years (range 3-15) all patients were determined to have a high serum Tg concentrations (>2 ng/ml) and previous negative I-131 WBS results. All patients were examined for metastatic sites using Tc-99m-MIBI scan. Scans were visually evaluated for detecting lymph node metastases and/or local recurrence, lung metastases and skeletal metastases.


RESULTS
Tc-99m-MIBI scan demonstrated lesions in 23 patients (83.3%). In five patients with negative Tc-99m-MIBI scan findings (FN results): Chest CT showed small-sized mediastinal LN metastases in 2 patients and lung metastases in another 2 patients (<1 cm). Neck CT showed small-sized cervical LN involvement in 1 patient. The sensitivity of detection for neck was 94.4%, for lung 63.6%, and for bone lesions 100%. For all scan sites taken together, the sensitivity of disease detection was 83.3%, the specificity was 50%, positive predictive value (PPV) was 96.2%, and finally negative predictive value (NPV) was 16.7%.


CONCLUSIONS
We concluded that Tc-99m-MIBI scan should be considered as a supplementary scintigraphic method for the follow-up of patients with high serum Tg levels and negative I-131 WBS results, and it can help clinicians in making the decision to treat these patients.
Küçük
Nuriye Ozlem
NO
Department of Nuclear Medicine, Ankara University Faculty of Medicine, Ankara, Turkey. okucuk@medicine.ankara.edu.tr
Külak
Hülya Atalay
HA
Aras
Gülseren
G
D000328:Adult; D002277:Carcinoma / Q000000981:diagnostic imaging* / Q000556:secondary*; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008207:Lymphatic Metastasis; D008297:Male; D011379:Prognosis; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D017256:Technetium Tc 99m Sestamibi; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood* / Q000000981:diagnostic imaging*; D051598:Whole Body Imaging
D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D013954:Thyroglobulin; D017256:Technetium Tc 99m Sestamibi