Ultrasound of Benign Thyroid Nodules: A 120 Months Follow-Up Study

Carlo Cappelli; Ilenia Pirola; Elena Gandossi; Mario Rotondi; Claudio Casella; Davide Lombardi; Barbara Agosti; Alberto Ferlin; Maurizio Castellano


Clin Endocrinol. 2021;94(5):866-871. 

In This Article

Subjects and Methods

We reviewed the medical and imaging records of patients who were submitted to ultrasound-guided FNA of thyroid nodules at our hospital from January 2007 to March 2009. We selected only patients with benign nodules who underwent annual ultrasound evaluation in our Department for ten years, consecutively; for multinodular goitre, we selected only patients for whom FNA was performed on a single nodule. Patients with cystic lesions were excluded from this study.

We used a LOGIQ 9 (GE, Healthcare) or AplioTM500 (Toshiba Medical Systems Corp.) ultrasonographic scanner fitted with a 10–14-MHz linear transducer for morphological study. All the three diameters of the nodules (anteroposterior, transverse and longitudinal) were measured in each examination, and the volume of the nodule was calculated according to the ellipsoid formula V = πabc/6 (where V is volume, a is the largest diameter and b and c are the other two orthogonal diameters). Nodule size changes were considered significant if the increase or decrease involved at least 2 nodule dimensions with a volume change of at least 50%. FNA was repeated in the case of nodular growth. All ultrasound examinations were performed by an experienced endocrinologist.[15–18] We have previously assessed that the repeatability coefficient of ultrasound measurement of thyroid nodule size (ie the maximum difference that is likely to occur between repeated measurements) for the sonographer involved in the present study is 0.998 mm.[6] Thyrotropin (TSH) levels were evaluated annually at each control. Serum concentrations of TSH (normal range 0.4–4.5 mIU/L, analytical sensitivity 0.004 mIU/L) were measured using a fully automated Architect i2000 analyser (Abbott Diagnostics) using chemiluminescent magnetic immunoassays.

The study was conducted according to the principles of the Helsinki Declaration and the guidelines of the Institutional Ethical Committee. All patients gave written informed consent to their enrolment in this study and for the storage and use of their data.

The study was approved by the Comitato Etico di Brescia (no. 4084).

Statistical Analysis

All data were collected in an electronic case report database. Comparisons between groups and difference between proportions were calculated using chi-square for categorical variables and ANOVA test for quantitative variables, as appropriate. An analysis of variance for repeated measurements using a longitudinal linear model was applied to estimate changes over 10 years of original nodule volume and diameter. A multiple regression analysis was performed to examine the influence of confounders (gender, age and TSH etc) on nodular growth in the whole group of patients. Two-tailed P < .05 was considered statistically significant. Statistical analyses were performed using SPSS 20.0 software (SPSS, Inc).