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Erschienen in:
01.01.2014 | Original Article
Combined 99mTc-methoxyisobutylisonitrile scintigraphy and fine-needle aspiration cytology offers an accurate and potentially cost-effective investigative strategy for the assessment of solitary or dominant thyroid nodules
Erschienen in: European Journal of Nuclear Medicine and Molecular Imaging | Ausgabe 1/2014
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Purpose
Fine-needle aspiration (FNA) has revolutionised the care of patients with thyroid nodules and is the initial investigation of choice. However, as a result of nondiagnostic (Thy1) and nonneoplastic (Thy2) specimens, it remains an imperfect sole solution with a range of sensitivities and a high inadequate ratio. Therefore the British Thyroid Association (BTA) guidelines recommend a second FNA immediately for Thy1 specimens and 3–6 months later for Thy2 specimens. Patients must be followed up to exclude malignancy. In this study we assessed the performance of MIBI scintigraphy for diagnosing thyroid malignancy and the cost-effectiveness of a combined FNA/MIBI investigative strategy for the management of thyroid nodules.
Methods
The diagnostic performance of MIBI scintigraphy was calculated from a retrospective review of local data combined with a meta-analysis of the published literature. Decision tree analysis was used to calculate the cost-effectiveness of a combined FNA/MIBI investigative strategy compared to the BTA guidelines.
Results
From 712 patients, the sensitivity, specificity, PPV and NPV of MIBI scintigraphy for the diagnosis of malignancy were 96 %, 46 %, 34 % and 97 %, respectively. MIBI-based strategies were more accurate and associated with lower cost per patient (£1,855/€2,125 vs. £2,445/€2,801) and lower cost per cancer diagnosed (£1,902/€2,179 vs. £2,469/€2,828) with negligible change in life expectancy.
Conclusion
Due to its high NPV, MIBI scintigraphy can usefully exclude malignancy for Thy1 and Thy2 lesions. Its low specificity means MIBI scintigraphy cannot be recommended as a first-line investigation, but as a second-line investigation MIBI scintigraphy may lead to a lower rate of unnecessary thyroidectomies. Combined FNA/MIBI strategies are potentially cost-effective in the management of solitary or dominant thyroid nodules.