ACCURACY OF SONOGRAPHY-GUIDED VERSUS CONVENTIONAL FINE NEEDLE ASPIRATION BIOPSY

Ultrasound guidance has been suggested as a valuable aid to enhance Fine Needle Aspiration Biopsy (FNAB) performance in the preoperative diagnosis of thyroid nodules. We compared diagnostic accuracy of conventional FNAB (C-FNAB) versus sonography-guided FNAB (SG-FNAB) by reviewing a large sample population of 9,683 patients with thyroid nodules. 4,986 patients were investigated by C-FNAB while 4,697 underwent SG-FNAB. A valuable cytologic diagnosis was obtained in 85.9% of C-FNAB and in 91.5% of SG-FNAB cases, thyroid cancer being detected in 1.6% and 2.1% of patients, respectively. Specimens were inadequate for cytology (8.7%) but only in 167 SG-FNAB cases (3.5%). The indeterminate pattern of follicular neoplasia was equally observed in 238 C-FNAB (5%) and in 272 (5.4%) SG-FNAB nodules. A total of 535 C-FNAB and 540 SG-FNAB patients underwent surgery. False-negative results occurred in 7 (2.3%) C-FNAB but only in 3 (1%) SG-FNAB cases. Sensitivity, specificity and global diagnostic accuracy of C-FNAB as compared to SG-FNAB were 91.8% vs. 97.1%, 68.8% vs. 70.9% and 72.6% vs. 75.9%, respectively. In conclusion, SG-FNAB allows a more precise and adequate sampling of thyroid nodular lesions and is associated to a lower rate of false negative diagnoses thus improving overall diagnostic accuracy in the preoperative selection of thyroid cancer. (Work supported by AIRC and MURST research grants).