Is (18)F-fluorodeoxyglucose-PET/CT useful for the presurgical characterization of thyroid nodules with indeterminate fine needle aspiration cytology?

Abstract

BACKGROUND:

Thyroid nodules found incidentally on (18)F-fluorodeoxyglucose-positron emission tomography (FDG-PET) have been shown to be malignant in 30%-50% of cases. The American Thyroid Association recommends performing fine needle aspiration cytology (FNAC) for thyroid nodules showing FDG uptake. On the other hand, the role of FDG-PET in characterizing thyroid nodules with indeterminate cytology before surgery is not clear. The goal of this study was to evaluate the role of FDG-PET/computed tomography (CT) in predicting malignancy of thyroid nodules with indeterminate FNAC and to correlate FDG uptake with pathological and ultrasonographic (US) features.

METHODS:

Between November 2006 and October 2009, 55 patients (42 women, mean age: 50 years) planned for surgery for 56 thyroid nodules with indeterminate FNAC were prospectively included and considered for analysis. All patients underwent presurgical FDG-PET/CT (Siemens Biograph, mean FDG injected activity: 165 MBq) and neck US. Pathology of the corresponding surgical specimen was the gold standard for statistical analysis.

RESULTS:

At pathology 34 nodules were benign, 10 were malignant (7 papillary and 3 follicular carcinomas), and 12 were tumors of uncertain malignant potential (TUMP). The median size of the thyroid nodules was 21 mm (range: 10-57). Sensitivity, specificity, positive (PPV), and negative predictive (NPV) values of FDG-PET in detecting cancer/TUMP were 77%, 62%, 57%, and 81%, respectively. In multivariate analysis, cellular atypia was the only factor predictive of FDG uptake (p<0.001). Hurthle cells and poorly differentiated components were independent predictive factors of high (≥5) SUV Max (p=0.02 and p=0.02). Sensitivity, specificity, PPV, and NPV of US in detecting cancer/TUMP were 82%, 47%, 50%, and 80%, respectively. In multivariate analysis, hypervascularization was correlated with malignancy/TUMP (p=0.007) and cystic features were correlated with benignity (p=0.03).

CONCLUSION:

Adding FDG-PET findings to neck US provided no diagnostic benefit. The sensitivity and specificity of FDG-PET in the presurgical evaluation of indeterminate thyroid nodules are too low to recommend FDG-PET routinely.

• Authors: Desiree Deandreis, Abir Al Ghuzlan, Anne Auperin, Philippe Vielh, Bernard Caillou, Linda Chami, Jean Lumbroso, Jean Paul Travagli, Dana Hartl, Eric Baudin, Martin Schlumberger, Sophie Leboulleux
• Journal: Thyroid : official journal of the American Thyroid Association (Thyroid) Vol. 22 Issue 2 Pg. 165-72 (Feb 2012) ISSN: 1557-9077 [Electronic] United States
• PMID: 22257371 (Publication Type: Journal Article)

Chemical References

• Fluorodeoxyglucose F18

Topics

• Adenocarcinoma, Follicular (diagnostic imaging)
• Adult
• Aged
• Biopsy, Fine-Needle
• Carcinoma, Papillary (diagnostic imaging)
• Female
• Fluorodeoxyglucose F18
• Humans
• Male
• Middle Aged
• Multimodal Imaging (methods)
• Positron-Emission Tomography
• Sensitivity and Specificity
• Thyroid Neoplasms (diagnostic imaging)
• Thyroid Nodule (diagnostic imaging)
• Tomography, X-Ray Computed
• Ultrasonography