Echo pattern characteristics on radial endobronchial ultrasonography and their diagnostic implications

Visual assessment using radial endobronchial ultrasonography (R-EBUS) remains subjective. The current study aimed to examine characteristic echo patterns—including heterogeneity, hyperechoic areas, and vascular visibility—and to validate their diagnostic implications for differentiating malignant from benign peripheral pulmonary lesions. Sixty-eight peripheral pulmonary lesions were retrospectively analyzed. From representative R-EBUS images, three rectangular regions of interest were placed at proximal (near the probe) and distal (deeper within the lesion) locations. The mean and standard deviation (SD) of grayscale intensity were calculated, and visual findings such as hyperechoic areas and vessel patency were evaluated by two independent observers. Discrepancies were resolved by a third reviewer. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of malignancy. Malignant lesions had a significantly higher SD of grayscale intensity in the proximal region than benign ones (11.14 ± 0.19 vs 10.18 ± 0.33, p = 0.015). Grayscale intensity remained an independent predictor of malignancy in the multivariate analysis (adjusted odds ratio: 1.91, 95% confidence interval: 1.20–3.33, p = 0.006). Based on an analysis across diagnostic subtypes, malignant lesions generally had a higher proximal SD. Meanwhile, both malignant and benign lesions exhibited substantial variability in terms of grayscale intensity and internal echo patterns. Hyperechoic structures were common in adenocarcinoma and organizing pneumonia. However, they were rarely observed in metastatic lesions and small-cell carcinoma. Vessels were frequently found in organizing pneumonia but were absent in fungal/mycobacterial infections. Distinct echo pattern characteristics on R-EBUS reflect the internal architecture of pulmonary lesions. Further, they provide diagnostic implications for differentiating malignant from benign diseases. The identification of subtype-specific echo diversity may enhance interpretative accuracy in future studies.