Pierpaolo Trimboli1, Gaetano Paone1, Giorgio Treglia1,2,3, Camilla Virili4, Teresa Ruberto1, Luca Ceriani1, Arnoldo Piccardo1, Luca Giovanella1. 1. Department of Nuclear Medicine and Thyroid Centre, Oncology Institute of Southern Switzerland, Bellinzona, Switzerland. 2. Department of Nuclear Medicine and Molecular Imaging, Lausanne University Hospital, Lausanne, Switzerland. 3. Health Technology Assessment Unit, Academic Education, Research and Innovation Area, Ente Ospedaliero Cantonale, Bellinzona, Switzerland. 4. Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Latina, Italy.
Abstract
OBJECTIVE: Focal thyroid incidentalomas (TIs) are observed in 2% of 18 F-FDG PET/CT representing malignancy in one-third of cases. Currently, due to the lack of evidence on their optimal management, guidelines suggest fine-needle aspiration cytology (FNAC). The study aim was to evaluate the role of ultrasound evaluation according to EU-TIRADS to assess the risk of TIs and inform FNAC prescriptions. DESIGN: We retrospectively reviewed 18 F-FDG PET/CT TIs recorded during the period 2014-2017. Enrolled were TIs with histological outcome and autonomous nodules. Cases with uncertain matching between 18 F-FDG PET/CT, ultrasound and histology were excluded. RESULTS: According to the selection criteria, 75 TIs, being 13 (17.3%) malignant and 62 (82.7%) benign, were included. Cancers had significantly higher SUVmax and SUVmax ratio (Mann-Whitney P < 0.01) than benign, and the most accurate cut-offs were >7.1 and >3.65, respectively. At ultrasound, the cancer rate was 0% in EU-TIRADS 2, 2.9% in EU-TIRADS 3, 4.2% in EU-TIRADS 4% and 78.6% in EU-TIRADS 5 (chi-squared P < 0.001). Sensitivity, specificity, PPV, NPV and accuracy for malignancy were 92%, 64%, 35%, 98% and 69% for SUVmax; 85%, 68%, 36%, 96% and 71% for SUVmax ratio; and 85%, 95%, 79%, 97% and 93% for EU-TIRADS, respectively. The absence of all these three features reached a specificity of 97.1%. CONCLUSIONS: EU-TIRADS, within a clinical careful approach, can discriminate with significant accuracy lesions at high risk of malignancy from those at low risk among TIs at 18 F-FDG PET/CT. Additionally, a centre-based threshold for SUV parameters should be useful for the initial assessment of these lesions during PET/CT reading and reporting.
OBJECTIVE: Focal thyroid incidentalomas (TIs) are observed in 2% of 18 F-FDG PET/CT representing malignancy in one-third of cases. Currently, due to the lack of evidence on their optimal management, guidelines suggest fine-needle aspiration cytology (FNAC). The study aim was to evaluate the role of ultrasound evaluation according to EU-TIRADS to assess the risk of TIs and inform FNAC prescriptions. DESIGN: We retrospectively reviewed 18 F-FDG PET/CT TIs recorded during the period 2014-2017. Enrolled were TIs with histological outcome and autonomous nodules. Cases with uncertain matching between 18 F-FDG PET/CT, ultrasound and histology were excluded. RESULTS: According to the selection criteria, 75 TIs, being 13 (17.3%) malignant and 62 (82.7%) benign, were included. Cancers had significantly higher SUVmax and SUVmax ratio (Mann-Whitney P < 0.01) than benign, and the most accurate cut-offs were >7.1 and >3.65, respectively. At ultrasound, the cancer rate was 0% in EU-TIRADS 2, 2.9% in EU-TIRADS 3, 4.2% in EU-TIRADS 4% and 78.6% in EU-TIRADS 5 (chi-squared P < 0.001). Sensitivity, specificity, PPV, NPV and accuracy for malignancy were 92%, 64%, 35%, 98% and 69% for SUVmax; 85%, 68%, 36%, 96% and 71% for SUVmax ratio; and 85%, 95%, 79%, 97% and 93% for EU-TIRADS, respectively. The absence of all these three features reached a specificity of 97.1%. CONCLUSIONS: EU-TIRADS, within a clinical careful approach, can discriminate with significant accuracy lesions at high risk of malignancy from those at low risk among TIs at 18 F-FDG PET/CT. Additionally, a centre-based threshold for SUV parameters should be useful for the initial assessment of these lesions during PET/CT reading and reporting.
Authors: Katarzyna Dobruch-Sobczak; Zbigniew Adamczewski; Marek Dedecjus; Andrzej Lewiński; Bartosz Migda; Marek Ruchała; Anna Skowrońska-Szcześniak; Ewelina Szczepanek-Parulska; Klaudia Zajkowska; Agnieszka Żyłka Journal: J Ultrason Date: 2022-04-27