Domenico Albano1, Giorgio Treglia2,3,4, Luca Giovanella2,5, Raffaele Giubbini6, Francesco Bertagna6. 1. Nuclear Medicine, University of Brescia and ASST Spedali Civili Brescia, Brescia, Italy. doalba87@libero.it. 2. Clinic of Nuclear Medicine and PET/CT Center, Imaging Institute of Southern Switzerland, Bellinzona, Switzerland. 3. Health Technology Assessment Unit, Ente Ospedaliero Cantonale, Bellinzona, Switzerland. 4. Department of Nuclear Medicine and Molecular Imaging, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland. 5. Clinic for Nuclear Medicine, University Hospital and University of Zürich, Zürich, Switzerland. 6. Nuclear Medicine, University of Brescia and ASST Spedali Civili Brescia, Brescia, Italy.
Abstract
PURPOSE: The incidence and clinical significance of thyroiditis detected by molecular imaging methods is a clinical challenge that is not widely investigated in the literature. The aim of this systematic review was to analyze published data about the detection of thyroiditis on PET or PET/CT using different tracers. METHODS: A comprehensive computer literature search of the Scopus, PubMed/MEDLINE, Embase, and Cochrane library databases was conducted up to November 2019 to find relevant papers on the detection of thyroiditis by PET/CT, the metabolic appearance, and the clinical significance. RESULTS: Twenty-six articles were selected and retrieved in full-text version. From the analyses of these studies, the following main findings have been found. Diffuse thyroid uptake of PET tracers is a relatively frequent event, ranging from 0.4 to 46.2%, and it is commonly related to benign disease. Thyroiditis is the most frequent reason for diffuse increased thyroid 18F-FDG uptake. Cases of malignant disease with a pattern of diffuse 18F-FDG thyroid uptake are less frequent. Preliminary studies show a possible role of thyroiditis detected by 18F-FDG PET/CT in evaluating treatment response and as a prognostic marker in oncological patients treated with immunotherapy. However, further studies are needed. CONCLUSIONS: Diffuse 18F-FDG thyroid uptake is a relatively rare event commonly due to benign diseases, among which thyroiditis is the most common. The rate of neoplastic disease with diffuse 18F-FDG thyroid uptake is very low. Diffuse 18F-FDG thyroid uptake requires further investigation and clinical evaluation for the correct diagnosis. Currently, cases of diffuse thyroid uptake with non-18F-FDG radiotracer are only anecdotal.
PURPOSE: The incidence and clinical significance of thyroiditis detected by molecular imaging methods is a clinical challenge that is not widely investigated in the literature. The aim of this systematic review was to analyze published data about the detection of thyroiditis on PET or PET/CT using different tracers. METHODS: A comprehensive computer literature search of the Scopus, PubMed/MEDLINE, Embase, and Cochrane library databases was conducted up to November 2019 to find relevant papers on the detection of thyroiditis by PET/CT, the metabolic appearance, and the clinical significance. RESULTS: Twenty-six articles were selected and retrieved in full-text version. From the analyses of these studies, the following main findings have been found. Diffuse thyroid uptake of PET tracers is a relatively frequent event, ranging from 0.4 to 46.2%, and it is commonly related to benign disease. Thyroiditis is the most frequent reason for diffuse increased thyroid 18F-FDG uptake. Cases of malignant disease with a pattern of diffuse 18F-FDG thyroid uptake are less frequent. Preliminary studies show a possible role of thyroiditis detected by 18F-FDG PET/CT in evaluating treatment response and as a prognostic marker in oncological patients treated with immunotherapy. However, further studies are needed. CONCLUSIONS: Diffuse 18F-FDG thyroid uptake is a relatively rare event commonly due to benign diseases, among which thyroiditis is the most common. The rate of neoplastic disease with diffuse 18F-FDG thyroid uptake is very low. Diffuse 18F-FDG thyroid uptake requires further investigation and clinical evaluation for the correct diagnosis. Currently, cases of diffuse thyroid uptake with non-18F-FDG radiotracer are only anecdotal.