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. 2009 Aug 10:7:63.
doi: 10.1186/1477-7819-7-63.

Incidental thyroid lesions detected by FDG-PET/CT: prevalence and risk of thyroid cancer

Ja Seong Bae  1 , Byung Joo Chae, Woo Chan Park, Jeong Soo Kim, Sung Hoon Kim, Sang Seol Jung, Byung Joo Song
Affiliations

Incidental thyroid lesions detected by FDG-PET/CT: prevalence and risk of thyroid cancer

Ja Seong Bae et al. World J Surg Oncol. .

Abstract

Background: Incidentally found thyroid lesions are frequently detected in patients undergoing FDG-PET/CT. The aim of this study was to investigate the prevalence of incidentally found thyroid lesions in patients undergoing FDG-PET/CT and determine the risk for thyroid cancer.

Methods: FDG-PET/CT was performed on 3,379 patients for evaluation of suspected or known cancer or cancer screening without any history of thyroid cancer between November 2003 and December 2005. Medical records related to the FDG-PET/CT findings including maximum SUV(SUVmax) and pattern of FDG uptake, US findings, FNA, histopathology received by operation were reviewed retrospectively.

Results: Two hundred eighty five patients (8.4%) were identified to have FDG uptake on FDG-PET/CT. 99 patients with focal or diffuse FDG uptake underwent further evaluation. The cancer risk of incidentally found thyroid lesions on FDG-PET/CT was 23.2% (22/99) and the cancer risks associated with focal and diffuse FDG uptake were 30.9% and 6.4%. There was a significant difference in the SUVmax between the benign and malignant nodules (3.35 +/- 1.69 vs. 6.64 +/- 4.12; P < 0.001). There was a significant correlation between the SUVmax and the size of the cancer.

Conclusion: The results of this study suggest that incidentally found thyroid lesions by FDG-PET/CT, especially a focal FDG uptake and a high SUV, have a high risk of thyroid malignancy. Further diagnostic work-up is needed in these cases.

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Figures

Figure 1
Figure 1
Focal FDG uptake on PET/CT. 54 year old female with breast cancer. The 18F-FDG PET/CT revealed focal uptake with SUV of 7.6. The patients was performed total thyroidectomy with a final diagnosis of papillary thyroid carcinoma.
Figure 2
Figure 2
Diffuse FDG uptatake on PET/CT. 53 year old male. The 18F-FDG PET/CT revealed diffuse uptake with SUV of 3.8. The sonographic features of the thyroid gland were strongly suggestive of the presence of thyroiditis.
Figure 3
Figure 3
SUVmax of benign and malignant thyroid lesions on PET/CT. Side by side box plots of SUVmax by groups. Statistically significant differences was found in SUVmax between benign lesions and malignant lesions (P < 0.001).
Figure 4
Figure 4
Correlation between SUVmax and cancer size. Spearman r test was performed to find correlation between SUVmax and thyroid cancer size. (Spearman r = 0.776, 95% confidence interval 0.50–0.91, P = 0.0001).
Figure 5
Figure 5
ROC curve to differentiate between benign and malignant lesions on PET/CT.
See this image and copyright information in PMC

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