Whirling technique for thyroid fine needle aspiration biopsy: a preliminary study of effectiveness and safety

PURPOSE: This study was aimed to compare thyroid fine needle aspiration biopsy (FNAB) techniques (conventional vs. whirling) in terms of cell harvesting ability ex vivo, the unsatisfactory rate and complication rate in vivo, and multi-operator performance in a phantom study. METHODS: In the ex vivo study, cell counts per background at ×100 magnification were compared between both techniques. In the in vivo study, 70 patients who underwent whirling FNAB from July 2019 to November 2019 were retrospectively compared to 140 matched patients who underwent conventional FNAB from January 2018 to November 2019 regarding the unsatisfactory rate and complication rate. As a subgroup analysis, thyroid nodules in difficult biopsy situations (nodule diameter <10 mm and location within 3 mm from major anatomical structures) were compared. In the phantom study, eight operators with varying experience recorded levels of dexterity and needle tip visualization, and their preferences for both techniques. RESULTS: In the ex vivo study, cell counts were comparable between both techniques in all thyroid nodule mimickers (80.0% vs. 87.5%, P=0.178). In the in vivo study, the unsatisfactory rate was comparable between the two groups (15.7% vs. 12.9%, P=0.859). In the subgroup analysis, the whirling technique demonstrated a lower unsatisfactory rate (5.9% vs. 24.2%, P=0.045) and a lower complication rate (0% vs. 6.1%, P=0.553). In the phantom study, the whirling technique demonstrated better dexterity and needle tip visualization and was preferred by all operators. CONCLUSION: This newly proposed whirling technique for thyroid FNAB may be effective and safe, especially in difficult biopsy situations.