Ultrasound-Guided Fine-Needle Aspiration Versus Fine-Needle Capillary Sampling Biopsy of Thyroid Nodules

Abstract

Both fine-needle aspiration (FNA) and fine-needle capillary (FNC) sampling of palpable thyroid nodules have been advocated. The appropriate technique for biopsy of nonpalpable nodules now sampled under ultrasound guidance has not been assessed. The objective of this study was to determine cytologic adequacy rates of ultrasound-guided FNA and FNC sampling. Ultrasound-guided fine-needle biopsy was performed on 180 thyroid nodules. Nodules were measured and characterized (mixed cystic-solid or solid) on diagnostic sonography. The technique used for biopsy (FNA versus FNC sampling) alternated sequentially per patient. Four 25-gauge fine-needle samples were obtained from each nodule. The sampling adequacy and cytopathologic diagnoses were recorded. The significance of differences in cytologic adequacy rates between techniques was then assessed with a repeated measures logistic regression model. Fine-needle aspiration and FNC sampling biopsies were performed in 88 and 92 nodules, respectively. Fine-needle aspiration was diagnostic (ie, satisfactory) in 78 (89%) of 88 nodules and nondiagnostic (less than optimal or unsatisfactory) in 10 (11%) of 88 nodules; FNC sampling was diagnostic in 80 (87%) of 92 nodules and nondiagnostic in 12 (13%) of 92 nodules. Fine-needle aspiration sampling was diagnostic in 38 (86%) of 44 solid nodules and 40 (91%) of 44 mixed cystic-solid nodules; FNC sampling was diagnostic in 48 (81%) of 59 solid nodules and 32 (97%) of 33 mixed cystic-solid nodules. These percentages were not significantly different. Ultrasound-guided FNA and FNC sampling result in comparable diagnostic cytologic adequacy rates. Equivalent diagnostic yields and the technical ease of capillary sampling may prompt adoption of FNC sampling at high-volume endocrine/radiology practices.