Performance of 18F-FDG PET/CT in Selecting Thyroid Nodules with Indeterminate Fine-Needle Aspiration Cytology for Surgery. A Systematic Review and a Meta-Analysis

Abstract

Thyroid nodules with indeterminate fine-needle aspiration cytology (FNA) represent a major challenge in clinical practice. We conducted a systematic review and meta-analysis evaluating the ability of hybrid imaging using fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) to appropriately select these nodules for surgery. PubMed, CENTRAL, Scopus, and Web of Science were searched until July 2019. Original articles reporting data on the performance of 18F-FDG PET/CT in thyroid nodules with indeterminate FNA were included. Summary operating points including 95% confidence interval values (95% CI) were estimated using a random-effects model. Out of 786 retrieved papers, eight studies evaluating 104 malignant and 327 benign thyroid nodules were included. The pooled positive and negative likelihood ratios (LR+ and LR-) and diagnostic odds ratio (DOR) of 18F-FDG PET/CT were 1.7 (95% CI: 1.4–2.0), 0.4 (95% CI: 0.2–0.7), and 3.5 (95% CI: 1.7–7.1), respectively. No heterogeneity was found for LR+ and DOR. In patients with thyroid nodules with indeterminate FNA, 18F-FDG PET/CT has a moderate ability to correctly discriminate malignant from benign lesions and could represent a reliable option to reduce unnecessary diagnostic surgeries. However, further studies using standardized criteria for interpretation are needed to confirm the reproducibility of these findings.

Radiofrequency ablation for treatment of thyroid follicular neoplasm with low SUV in PET/CT study

“…Furthermore, low SUVmax values in PET/CT (a cutoff value ranging from 2 to 5) have a low reported risk for thyroid cancers [19,23]. In our study, only two patients with high SUV follicular neoplasm underwent thyroidectomy (false positive: 23%, 2/6) with benign pathologies, which is consistent with previous studies (0-39%) [8,23].…”

“…Many studies have identified a high negative predictive value (83-96%) of 18 F-FDG PET/CT to rule out malignant thyroid nodules [22][23][24][25]. Superior diagnostic performance values of 18 F-FDG PET/CT are expected in patients presenting thyroid nodules with a diameter of >1 cm [19,22,24,25]. However, insufficient data exist to perform a subgroup analysis that excludes thyroid nodules with a diameter of <1 cm [19].…”

“…However, insufficient data exist to perform a subgroup analysis that excludes thyroid nodules with a diameter of <1 cm [19]. In recent years, PET/CT in combination with ultrasonography to discriminate benign from malignant cytologically indeterminate thyroid nodules has been introduced to avoid unnecessary diagnostic lobectomies, resulting in lower costs incurred by healthcare systems and a reported increase in health-related quality of life [19,26].…”

“…Studies have suggested that a follicular neoplasm can be managed by close follow-up and repeated FNA if patients are willing to accept a relatively low risk of cancer [3]. However, by using PET/CT, clinicians may more accurately distinguish high-risk follicular neoplasms and consequently recommend surgical intervention [19,23,37]. Meanwhile, for low-risk follicular neoplasms on PET/CT, RFA may offer a safe and feasible treatment option for patients unsuitable or unwilling to undergo surgery.…”

“…Positron emission tomography (PET/CT) in combination with ultrasonography to discriminate benign from malignant cytologically indeterminate thyroid nodules has been introduced to avoid unnecessary diagnostic lobectomies. Some studies have reported that PET/CT negative (SUVmax cutoff value < 5) indicates a low risk for thyroid cancers [19].…”