Supplementary Material for: Cone-beam CT-guided cryobiopsy combined with conventional biopsy for GGO-predominant pulmonary nodules

Introduction: Cryobiopsy (CB) using a 1.1-mm cryoprobe under fluoroscopic guidance is feasible and safe for diagnosis of ground glass opacity (GGO) lesions. However, the efficacy of CB combined with cone-beam CT (CBCT) for GGO-predominant pulmonary nodules remains elusive. Methods: We retrospectively studied patients who underwent CB combined with conventional biopsy under CBCT guidance for GGO-predominant pulmonary nodules with a consolidation to tumour ratio <50.0%. Results: A total of 32 patients with GGO-predominant pulmonary nodules were enrolled: 17 pure GGOs and 15 mixed GGOs. The mean lesion diameter was 15.81±5.52 mm and the overall diagnostic yield was 71.9%. Seven lesions were diagnosed by CB alone, which increased the diagnostic outcomes by 21.9%. Diagnostic yields for CB, forceps biopsy (FB), brushing and guide sheath flushing were 65.6%, 46.9%, 15.6% and 14.3%, respectively. Univariate analysis revealed that positive CT bronchus sign (P = 0.035), positive CBCT sign (P < 0.01) and CB-first biopsy sequence (P = 0.036) were significant predictive factors for higher diagnostic yield. Specimens obtained by CB had larger mean sample size (P < 0.01), lower blood cell area (P < 0.01) and fewer crush artefacts (P < 0.01) than specimens from FB. No severe bleeding or other complications occurred. Conclusion: Cryobiopsy using a 1.1-mm cryoprobe under cone-beam CT guidance increased diagnostic yield for GGO-predominant pulmonary nodules based on conventional biopsy. Further, it provided larger and nearly intact samples compared with forceps.