Risk of Malignancy in FDG‐Avid Thyroid Incidentalomas on PET/CT: A Prospective Study

Abstract

Background: Due to a substantial risk of malignancy, patients with focal FDG avid thyroid incidentalomas (FFTIs) on PET/CT are in most of Denmark referred to Head and Neck Cancer (HNC) fast track programs. The aim of this study was to determine the risk of malignancy in FFTI managed in a HNC fast track program. Methods: A prospective cohort study including all patients with FFTI referred to the HNC fast track program, Odense University Hospital between the 1 st of September 2016 and 31 st of August 2017. Ultrasonography (US) and fine-needle aspiration biopsy (FNAB) were intended to be done in all patients. Nodules with cytology of Bethesda 1, 3, 4, 5, or 6 were planned for surgical removal. Results: A total of 104 patients were included. All patients had US and 101 patients (97%) had FNAB. Forty-two patients had benign cytology classified as Bethesda 2. The remaining 62 patients underwent surgery except from 11 patients, mainly due to comorbidity. The overall risk of malignancy for patients with FFTI referred to our HNC fast track program was calculated to be 24% (23/95) based on patients with unequivocal cytology and/or histology. The only statistically significant US characteristic to predict malignancy was the appearance of irregular margins with a sensitivity of 47% and specificity of 96%. Conclusion: The risk of malignancy of FFTIs handled in our HNC fast track program is 24%.

Focal Thyroid Incidentalomas on 18F-FDG PET/CT: A Systematic Review and Meta-Analysis on Prevalence, Risk of Malignancy and Inconclusive Fine Needle Aspiration

“…In the index test domain, 16 studies were classified as being of unclear risk of bias as it was not described how 18 F-FDG PET/CTs were assessed ( 24 , 30 , 32 , 35 , 39 , 45 , 47 , 51 , 52 , 61 , 65 , 66 , 73 – 75 , 79 ).…”

“…Fifty studies provided information regarding the prevalence of 18 F-FDG-avid FTI. Of the 11 excluded studies, in 3 the prevalence data were not provided separately for focal and diffuse thyroid incidentalomas ( 39 , 63 , 80 ) and 8 did not report on the total number of 18 F-FDG PET/CTs ( 27 , 28 , 36 , 58 , 66 , 75 , 78 , 83 ).…”

“…(2) inconsequent description of data of non-diagnostic or indeterminate FNAC results (N = 5) ( 41 , 45 , 52 , 66 , 73 ). (3) missing separate data of BIII and BIV or THY3a and THY3b categories (N = 6) ( 31 , 47 , 57 , 70 , 75 , 76 ). (4) description of either non-diagnostic or indeterminate FNAC results and not both subgroups (N = 7) ( 34 , 38 , 46 , 48 , 50 , 78 , 79 ).…”

Long-Term Follow-Up of Thyroid Incidentalomas Visualized with 18F-Fluorodeoxyglucose Positron Emission Tomography—Impact of Thyroid Scintigraphy in the Diagnostic Work-Up

“…However, there is one drawback of this choice-as our patients were included from 1 January 2010 to 31 December 2013, the ultrasonography examinations did not report high-risk features of the nodules according to EU-TIRADS, as this strategy was not implemented until 2017 [20]. A recent Danish study evaluated the use of ultrasonography in diagnostic work-up in patients with ITN, reporting that an ultrasonography feature of irregular margins of the nodule gives the highest sensitivity and specificity with regard to malignancy; however, the authors commented that this feature is rather subjective as there are no strict rules on what an irregular margin looks like, and therefore this definition may vary among examiners [21].…”