A novel application of pulmonary transit time to differentiate between benign and malignant pulmonary nodules using myocardial contrast echocardiography

Malignant pulmonary nodules (PNs) are often accompanied by vascular dilatation and structural abnormalities. Pulmonary transit time (PTT) measurement by contrast echocardiograghy has used to assess the cardiopulmonary function and pulmonary vascular status, such as hepatopulmonary syndrome and pulmonary arteriovenous fistula, but has not yet been attempted in the diagnosis and differential diagnosis of PNs. The aim of this work was to evaluate the feasibility and performance of myocardial contrast echocardiography (MCE) for differentiating malignant PNs from benign ones. The study population consisted of 201 participant: 66 healthy participants, 65 patients with benign PNs and 70 patients with malignant PNs. Their clinical and conventional echocardiographic characteristics were collected. MCE with measurements of PTT were performed. There was no difference in age, sex, heart rate, blood pressure, smoking rate, background lung disease, pulmonary function, ECG, myocardial enzymes, cardiac size and function among the healthy participant, patients with benign and malignant PNs ( P > 0.05). PTT did not differ significantly in patients with PNs of different sizes, nor did they differ in patients with PNs of different enhancement patterns ( P > 0.05). However, the PTT were far shorter (about one half) in patients with malignant PNs than in patients with benign ones (1.88 ± 0.37 vs. 3.73 ± 0.35, P < 0.001). There was no significantly different between patients with benign PNs and healthy participant (3.73 ± 0.35 vs.3.89 ± 0.36, P > 0.05). The area under the receiver operating characteristics curve (AUC) of PTT was 0.99(0.978–1.009) in discriminating between benign and malignant PNs. The optimal cutoff value was 2.78 s, with a sensitivity of 98.52%, a specificity of 97.34%, and a accuracy of 97.69%. MCE had a powerful performance in differentiating between benign and malignant PNs, and a pulmonary circulation time of < 2.78 s indicated malignant PNs.