Comparison of fine needle aspiration and non-aspiration cytology for diagnosis of thyroid nodules: A prospective, randomized, and controlled trial

Abstract

Objectives: To compare the sampling efficiency and diagnostic performance of ultrasound (US)-guided fine-needle aspiration cytology (FNAC) and fine-needle non-aspiration cytology (FNNAC) for thyroid nodules.

Materials and methods: 629 thyroid nodules in 629 cases (477 females, 152 males) were randomly subjected to FNAC or FNNAC from Jun 2014 to Feb 2015. Diagnostic performance was calculated in reference to the histological findings or follow-up results.

Results: 629 patients (152 men, 477 women) with 629 thyroid nodules were enrolled in the study. Pathological results were obtained in 173 nodules and benign nodules at FNA with more than six months' follow-up were found in 65 nodules. Tumor size for FNAC ranges from 3.0 to 51.0 mm (mean±SD; 10.2±6.9 mm); whereas FNNAC (2.0-43.0 mm; 11.9±7.7 mm). Non-diagnostic results were found in 7.59% (24/316) of FNNAC procedures and 7.59% (25/313) of FNAC (P > 0.05). Determinate and indeterminate results were found in 50.63% (160/316) and 41.77% (132/316) of FNNAC procedures, whereas 58.15% (182/313) and 33.87% (106/313) of FNAC (P < 0.05). In order to obtain determinate cytological results, FNAC might be more suitable than FNNAC for diagnosis of nodules with hypovascularity (51.38% vs. 41.78%, P < 0.05) and macrocalcifications (9.72% vs. 6.50%, P < 0.05). No US and Color-Doppler US characteristics, such as the presence of hypervascularity (P > 0.05), microcalcifications (P > 0.05), internal component (P > 0.05), or size(P > 0.05), were significantly different to obtain determinate cytological results between the FNAC and FNNAC groups. The sensitivity, specificity, positive predictive value, negative predictive value, accuracy of FNAC and FNNAC were as follows: 96.67% vs. 100%, 89.74% vs. 96.5%, 87.88% vs. 96.97%, 97.22% vs. 100%, 92.75% vs.98.36%, respectively (all P > 0.05).

Conclusions: Both FNAC and FNNAC are effective for diagnosis of thyroid nodules. However, FNAC is more effective than FNNAC to acquire determinate cytological results for nodules which US present hypovascularity and macrocalcifications.

Keywords: Ultrasound; cancer; cytology; fine needle; thyroid.