The effect of nodule size on diagnostic efficacy in fine needle aspiration biopsy of thyroid nodules
Dimitrios Thomas1, Ifigenia Kostoglou-Athanassiou1, Emmanouil Vassiliou1, Vassilios Liakos1, Fotini Chatzimarkou1, Anastasios Pappas1, Panagiotis Athanassiou2 & Philippos Kaldrymidis1
Fine needle aspiration is used extensively in the diagnostic evaluation of thyroid nodules. However, its diagnostic efficacy may be reduced by non-diagnostic findings. The aim was to study the effect of nodule size on the diagnostic efficacy of ultrasound-guided fine needle aspiration biopsy in thyroid nodules.
Ultrasound-guided fine needle aspiration biopsy was performed in 210 patients with thyroid nodules. Cytology results were compared to nodule size. Patients were stratified in 5 groups according to nodule size, group A (n=41) nodule size 0.10.426 cm3, group B (n=43) nodule size 0.4270.816 cm3, group C (n=42) nodule size 0.8171.593 cm3, group D (n=43) nodule size 1.5943.382 cm3 and group E (n=41) nodule size >3.39 cm3. Ultrasound guidance of the fine needle aspiration biopsy was performed in all patients using the same linear modifier (612 MHz) attached in a Toshiba ultrasound apparatus (SSA550A). Statistical evaluation of the results was performed using x2 test and ANOVA.
In group A thyroid nodule fine needle aspiration biopsy was successful in 43.9%, in group B 79.1%, in group C 76.2%, in group D 69.8% and in group E 58.5% (P=0.004, x2 test). The number of cystic nodules and the pattern of vascularization (central, peripheral or both) differed significantly between the groups studied.
Diagnostic efficacy of fine needle aspiration biopsy seems to increase in parallel to nodule size. However, this relationship was not apparent in very big nodules, nodule size >3.38 cm3, possibly due to confounding factors, such as the presence of cystic areas and increased vascularization within the very large thyroid nodules.