2.1 Patients
A retrospective study review was performed on 357 patient files with thyroid nodules who underwent US FNAC in our institution between January 2019 and December 2019.
Medical records, ultrasound findings, and cytologic results in all patients were retrospectively reviewed.
Thyroid nodule evaluation using ACR TI-RADS was performed prior to FNAC by the attending specialist.
All methods were carried out in accordance with relevant guidelines and regulations.
All experimental protocols were approved by the Ziv Medical Center human ethics Helsinki committee.
Informed consent was obtained from all subjects and/or their legal guardian(s).
2.2 US-Guided FNAC Procedure.
US-guided FNAC was performed by two expert physicians with more than 5 years FNAC US guided experience. As a routine, one expert uses the short axis approach, while the other uses the long axis approach. Patients are referred to either expert according to on-site availability.
All FNACs were performed using a 5–12 MHz linear transducer.
2.3 Cytologic preparation and diagnosis.
The collected material was expelled on glass slides, smeared and fixed in 95% ethyl alcohol immediately following FNAC. Staining was performed using the Papanicolaou method.
An adequate sample was defined as having at least six clusters of thyroid follicular cells (15–20 cells) for each specimen.
All the samples were reported using the Bethesda System as follows: nondiagnostic (category I), (ND); (II) benign; (III) atypia or follicular lesion of undetermined significance (AUS/FLUS); (IV) follicular neoplasm or suspicious for follicular neoplasm (FN/SFN); (V) suspicious for malignancy (SM); and (VI) malignant.6-7
The rate of nondiagnosis (category I) between the two techniques mentioned above were compared, as well as other categories of the samples that were obtained. All slides were reviewed first by the attending cytopathologist, and subsequently confirmed by chief cytopathologist.
Statistical analysis
For categorical variables, summary tables will provide giving sample size, and relative frequencies. For continuous variables, a summary will provide the arithmetic mean and standard deviation (SD). Quantitative data are shown as the mean ± standard deviation, whereas numbers and percentage were provided for the qualitative data. Pearson’s chi-squared was applied to test the correlations between the study groups for the categorical parameters. A P-value of 5% or less will be considered statistically significant. Statistical analyses were performed using SPSS version 25 (SPSS Inc., Chicago, IL, USA).
Data collection:
Patient files were reviewed for ND results (category I) to compare the two techniques. The following data were collected and analyzed: age, sex, anatomic location of the biopsy, thyroid nodule size, biopsy technique, TIRADS and FNA Bethesda results.