Learning Curve for CT-Guided Percutaneous Transthoracic Core Needle Biopsy: Retrospective Evaluation Among 17 Thoracic Imaging Fellows at a Tertiary Referral Hospital.

Background: CT-guided percutaneous transthoracic needle biopsy (PTNB) is widely used for evaluation of indeterminate pulmonary lesions, though guidelines are lacking regarding the experience needed to gain sufficient skill. Objective: To investigate the learning curve among a large number of operators in a tertiary referral hospital and to determine the number of procedures required to obtain acceptable performance. Methods: This retrospective study included CT-guided PTNBs with coaxial technique performed by 17 thoracic imaging fellows from March 2011 to August 2017 who were novices in the procedure. A maximum of 200 consecutive procedures per operator were included. Cumulative summation method was used to assess learning curves for diagnostic accuracy, false negative rate, pneumothorax rate, and hemoptysis rate. Operators were assessed individually and in a pooled analysis. Pneumothorax risk was also assessed in a model adjusting for risk factors. Acceptable failure rates were defined as 0.1 for diagnostic accuracy and false negative rate; 0.45 for pneumothorax rate; and 0.05 for hemoptysis rate. Results: The study included 3261 procedures in 3134 patients (mean age, 67.7±12.1 years; 1876 men, 1258 women). Overall diagnostic accuracy was 94.2% (2960/3141). All 17 operators achieved acceptable diagnostic accuracy [37 procedures required in pooled analysis; median of 33 procedures (range 19-67) required]. Overall false negative rate was 7.6% (179/2370). All 17 operators achieved acceptable false negative rate [52 procedures required in pooled analysis; median of 33 procedures (range 19-95) required]. Pneumothorax occurred in 32.6% (1063/3261), and hemoptysis in 2.7% (89/3261). All 17 operators achieved acceptable pneumothorax rate [20 procedures required in pooled analysis; median of 19 procedures (range 7-63) required]. In the risk-adjusted model, 15 operators achieved acceptable pneumothorax rate [54 procedures required in pooled analysis; median of 36 procedures (range 10-192) required]. Sixteen operators achieved acceptable hemoptysis rate [67 procedures required in pooled analysis; median of 55 procedures (range 41-152) required]. Conclusion: For CT-guided PTNB, at least 37 and 52 procedures are required to achieve acceptable diagnostic accuracy and false negative rate, respectively. Not all operators achieved acceptable complication rates. Clinical Impact: The findings may help set standards for training, supervision, and ongoing assessment of proficiency for this procedure.