{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,20]],"date-time":"2026-05-20T15:16:15Z","timestamp":1779290175482,"version":"3.51.4"},"reference-count":23,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2021,8,7]],"date-time":"2021-08-07T00:00:00Z","timestamp":1628294400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diagnostics"],"abstract":"<jats:p>Background: As reported in the literature, [18F]-fluorodeoxyglucose positron emission tomography\/computed tomography ([18F]-FDG PET\/CT) provides useful qualitative and semi-quantitative data for the prognosis of advanced differentiated thyroid cancer. Instead, there is a lack of data about the real clinical impact of 18F-FDG PET\/CT on the choice of the more effective therapeutic approach for advanced differentiated thyroid cancer (DTC) that starts to lose iodine avidity. The primary aim of this retrospective study was to assess how 18F-FDG PET\/CT can guide the choice of the best therapeutic approach to RAI-refractory DTC (RAI-R-DTC) in patients with a doubtful iodine uptake\/negative 18F-FDG PET\/CT I whole-body scan after several radioactive iodine therapies (RAIT). The secondary aim was to assess the prognostic role of clinical and semi-quantitative metabolic 18F-FDG PET\/CT parameters in comparison to published data. Materials and methods: A monocentric retrospective observational study was performed, reviewing the medical records of 53 patients recruited from a database of 208 patients treated at our Institution between 2011 and 2019, with advanced DTC that underwent FDG PET\/CT scan for a suspected RAI-R-DTC. Selected patients had to perform a 18F-FDG PET\/CT scan after the second RAIT based on a doubtful iodine uptake\/negative 131 I whole-body scan and\/or persistent elevated thyroglobulin levels. Metabolic response was defined according to positron emission tomography response criteria in solid tumors (PERCIST) guidelines. Standardized uptake value (SUV)max, SUVmean, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were calculated. The association between metabolic features, clinical parameters and progression free survival (PFS) was assessed applying Kruskal\u2013Wallis, chi-square-Pearson correlation tests, and Cox regression analyses when appropriate. Results: Among our sample of 53 patients (mean age 52.0 \u00b1 19.9 years; 31 women and 22 men), 27 (51.0%) presented a positive 18F-FDG PET\/CT scan: 16 (59.0%) underwent watchful waiting, 4 (15.0%) received external-beam radiation therapy (EBRT), 4 (15.0%) underwent surgery, 2 (7.4%) received another course of RAI therapy, and 1 underwent surgery + EBRT. PERCIST response was evaluated in 14\/27 patients. Median follow-up was 5.8 \u00b1 3.9 years and median PFS was 38.0 \u00b1 21.8 months. At the last follow-up assessment, 14\/53 (26.4%) demonstrated disease progression, 13\/53 (24.5) persistence of structural disease, 25\/53 (47%) persistence of biochemical disease, and 15\/53 (28%) had an excellent response. A significant association was found between therapeutic approach, metabolic response, and final disease response evaluation, as well as a linear correlation between MTV and TLG with thyroglobulin level. Conclusions: Our Institutional experience confirmed the role of 18F-FDG PET\/CT as a useful guide in the clinical management of RAI-R-DTC and obviated further unnecessary RAIT.<\/jats:p>","DOI":"10.3390\/diagnostics11081430","type":"journal-article","created":{"date-parts":[[2021,8,8]],"date-time":"2021-08-08T21:49:41Z","timestamp":1628459381000},"page":"1430","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":12,"title":["Impact of 18F-FDG PET\/CT on Clinical Management of Suspected Radio-Iodine Refractory Differentiated Thyroid Cancer (RAI-R-DTC)"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2412-5807","authenticated-orcid":false,"given":"Elisa","family":"Lodi Rizzini","sequence":"first","affiliation":[{"name":"Radiation Oncology Unit, IRCSS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Andrea","family":"Repaci","sequence":"additional","affiliation":[{"name":"Division of Endocrinology, IRCSS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Elena","family":"Tabacchi","sequence":"additional","affiliation":[{"name":"Nuclear Medicine Unit, IRCSS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lucia","family":"Zanoni","sequence":"additional","affiliation":[{"name":"Nuclear Medicine Unit, IRCSS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Valentina","family":"Vicennati","sequence":"additional","affiliation":[{"name":"Division of Endocrinology, IRCSS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ottavio","family":"Cavicchi","sequence":"additional","affiliation":[{"name":"Department of Otolaryngology Head and Neck Surgery, IRCSS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Uberto","family":"Pagotto","sequence":"additional","affiliation":[{"name":"Division of Endocrinology, IRCSS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"},{"name":"Nuclear Medicine Unit, IRCSS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"},{"name":"Department of Otolaryngology Head and Neck Surgery, IRCSS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"},{"name":"Department of Experimental, Diagnostic and Specialty Medicine\u2013DIMES, Alma Mater Studiorum, University of Bologna, 40138 Bologna, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9793-3410","authenticated-orcid":false,"given":"Alessio Giuseppe","family":"Morganti","sequence":"additional","affiliation":[{"name":"Radiation Oncology Unit, IRCSS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"},{"name":"Division of Endocrinology, IRCSS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"},{"name":"Nuclear Medicine Unit, IRCSS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"},{"name":"Department of Otolaryngology Head and Neck Surgery, IRCSS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"},{"name":"Department of Experimental, Diagnostic and Specialty Medicine\u2013DIMES, Alma Mater Studiorum, University of Bologna, 40138 Bologna, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1486-2624","authenticated-orcid":false,"given":"Stefano","family":"Fanti","sequence":"additional","affiliation":[{"name":"Nuclear Medicine Unit, IRCSS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"},{"name":"Department of Otolaryngology Head and Neck Surgery, IRCSS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"},{"name":"Department of Experimental, Diagnostic and Specialty Medicine\u2013DIMES, Alma Mater Studiorum, University of Bologna, 40138 Bologna, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fabio","family":"Monari","sequence":"additional","affiliation":[{"name":"Radiation Oncology Unit, IRCSS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,8,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1089\/thy.2015.0020","article-title":"2015 American Thyroid Association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer: The Amercan Thyroid Association guidelines task force on thyroid nodules and diferentiated thyroid cancer","volume":"26","author":"Haugen","year":"2016","journal-title":"Thyroid"},{"key":"ref_2","first-page":"1626","article-title":"Different features of pulmonary metastases in differentiated thyroid cancer: Natural history and multivariate statistical analysis of prognostic variables","volume":"34","author":"Casara","year":"1993","journal-title":"J. Nucl. Med."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"4043","DOI":"10.1210\/jcem.84.11.6115","article-title":"Immediate causes of death in thyroid carcinoma: Clinicopathological analysis of 161 fatal cases","volume":"84","author":"Kitamura","year":"1999","journal-title":"J. Clin. Endocrinol. Metab."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"2892","DOI":"10.1210\/jc.2005-2838","article-title":"Long-term outcome of 444 patients with distant metastases from papillary and follicu-lar thyroid carcinoma: Benefits and limits of radioiodine therapy","volume":"91","author":"Durante","year":"2006","journal-title":"J. Clin. Endocrinol. Metab."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1053\/j.semnuclmed.2010.10.002","article-title":"The problem of the patient with thyroglobulin elevation but negative iodine scintigraphy: The TENIS syndrome","volume":"41","author":"Silberstein","year":"2011","journal-title":"Semin. Nucl. Med."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"93","DOI":"10.1530\/EJE-19-0261","article-title":"Diagnostic performance of 18F-FDG-PET\/CT in DTC patients with thyroglobulin elevation and negative iodine scintigraphy: A meta-analysis","volume":"181","author":"Qichang","year":"2019","journal-title":"Eur. J. Endocrinol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"904","DOI":"10.1055\/s-0032-1316351","article-title":"Impact of FDG-PET computed tomography for surgery of recurrent or persistent differentiated thyroid carcinoma","volume":"44","author":"Weber","year":"2012","journal-title":"Horm. Metab. Res."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"493","DOI":"10.1002\/hed.24357","article-title":"External-beam radiotherapy for differentiated thyroid cancer locoregional control: A statement of the American Head and Neck Society","volume":"38","author":"Kiess","year":"2016","journal-title":"Head Neck"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"122S","DOI":"10.2967\/jnumed.108.057307","article-title":"From RECIST to PERCIST: Evolving considerations for PET response criteria in solid tumors","volume":"50","author":"Wahl","year":"2009","journal-title":"J. Nucl. Med."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"228","DOI":"10.1016\/j.ejca.2008.10.026","article-title":"New response evaluation criteria in solid tumors: Revised RECIST guideline (version 1.1)","volume":"45","author":"Eisenhauer","year":"2009","journal-title":"Eur. J. Cancer"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"328","DOI":"10.1007\/s00259-014-2961-x","article-title":"FDG PET\/CT: EANM procedure guidelines for tumor imaging: Version 2.0","volume":"42","author":"Boellaard","year":"2015","journal-title":"Eur. J. Nucl. Med. Mol. Imaging"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"26","DOI":"10.1007\/s12149-011-0536-5","article-title":"Diagnostic accuracy of (18)F-fluorodeoxyglucose positron emission tomograpy\/computed tomog-raphy in differentiated thyroid cancer patients with elevated thyroglobulin and negative (131)I whole body scan: Evaluation by thyroglobulin level","volume":"26","author":"Na","year":"2012","journal-title":"Ann. Nucl. Med."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"541","DOI":"10.1586\/eem.12.36","article-title":"Radioactive iodine-refractory differentiated thyroid cancer: Unmet needs and future directions","volume":"7","author":"Pacini","year":"2012","journal-title":"Expert Rev. Endocrinol. Metab."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1530\/EJE-15-0066","article-title":"Imaging in endocrinology: 2-18F-fluoro-2-deoxy-D-glucose positron emission tomogra-phy\/computed tomography in differentiated thyroid carcinoma: Clinical indications and controversies in diagnosis and follow-up","volume":"173","author":"Salvatori","year":"2015","journal-title":"Eur. J. Endocrinol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"639","DOI":"10.1097\/MNM.0b013e32832dcfa7","article-title":"Value of 18F-FDG-PET\/PET-CT in differentiated thyroid carcinoma with radioiodine-negative whole-body scan: A meta-analysis","volume":"30","author":"Dong","year":"2009","journal-title":"Nucl. Med. Commun."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"159","DOI":"10.1677\/ERC-10-0233","article-title":"Do histological, immunohistochemical, and metabolic (radioiodine and fluorodeoxyglucose uptakes) patterns of metastatic thyroid cancer correlate with patient outcome?","volume":"18","author":"Deandreis","year":"2010","journal-title":"Endocr. Relat. Cancer"},{"key":"ref_17","first-page":"1107","article-title":"Prognostic value of 18F-fluorodeoxyglucose positron emission tomographic scanning in patients with thyroid cancer","volume":"85","author":"Wang","year":"2000","journal-title":"J. Clin. Endocrinol. Metab."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"469","DOI":"10.1097\/RLU.0000000000000780","article-title":"Prognostic value of 18F-FDG PET\/CT metabolic parameters in metastatic differentiated thyroid cancers","volume":"40","author":"Schvartz","year":"2015","journal-title":"Clin. Nucl. Med."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"641","DOI":"10.1097\/RLU.0000000000002193","article-title":"Prognostic value of FDG-PET\/CT metabolic parameters in metastatic radioio-dine-refractory differentiated thyroid cancer","volume":"43","author":"Manohar","year":"2018","journal-title":"Clin. Nucl. Med."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"856189","DOI":"10.1155\/2013\/856189","article-title":"The role of fluorine-18-fluorodeoxyglucose positron emission tomography in aggres-sive histological subtypes of thyroid cancer: An overview","volume":"2013","author":"Treglia","year":"2013","journal-title":"Int. J Endocrinol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1007\/s11547-013-0323-6","article-title":"Therapeutic impact of 18F-FDG PET\/CT in recurrent differentiated thyroid carcinoma","volume":"119","author":"Pomerri","year":"2014","journal-title":"Radiol. Med."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1586\/eem.11.83","article-title":"Positron emission tomography\/computed tomography in patients treated for differentiated thyroid carcinomas","volume":"7","author":"Giovanella","year":"2012","journal-title":"Expert Rev. Endocrinol. Metab."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"265","DOI":"10.1016\/j.cpet.2014.12.009","article-title":"Value of fluorodeoxyglucose PET\/computed tomography patient management and outcomes in thyroid cancer","volume":"10","author":"Ciarallo","year":"2015","journal-title":"PET Clin."}],"container-title":["Diagnostics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2075-4418\/11\/8\/1430\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T06:42:21Z","timestamp":1760164941000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2075-4418\/11\/8\/1430"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,8,7]]},"references-count":23,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2021,8]]}},"alternative-id":["diagnostics11081430"],"URL":"https:\/\/doi.org\/10.3390\/diagnostics11081430","relation":{},"ISSN":["2075-4418"],"issn-type":[{"value":"2075-4418","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,8,7]]}}}