NGHIÊN CỨU GIÁ TRỊ DELAYED PHASE CT TRONG ĐÁNH GIÁ NỐT ĐƠN ĐỘC Ở PHỔI

Abstract

Objective: To determine the imaging characteristics and malignancy indicators of solitary pulmonary nodules (SPNs) and to evaluate the diagnostic performance of delayed phase chest computed tomography (CT) in characterizing these nodules. Materials and Methods: This prospective cross-sectional study enrolled 125 patients with SPNs who were examined and treated at the National Lung Hospital between November 2019 and December 2021. All patients underwent chest CT and had histopathological confirmation by CT-guided percutaneous transthoracic biopsy and/or surgical resection. SPNs were assessed for shape, margin, size, location, internal features, and enhancement patterns. A subset of 34 patients underwent Dynamic CT with scans at 25 s, 60 s, and 4 min post-contrast; the remaining 91 patients underwent Delayed Phase CT at 60 s post-contrast. Contrast enhancement > 15 HU was considered significant. Statistical analysis was performed with SPSS 20.0; p < 0.05 was considered significant. Results: Of the 125 SPNs, 51.5% were benign and 48.5% malignant. The mean patient age was 53.5 ± 1.4 years (most common age group: 49–69 years), with a male:female ratio of 2.3:1. Nodule morphology was oval in 72%, round in 20%, lobulated in 1.6%, and irregular in 6.4%. Round nodules were predominantly benign (72%), whereas oval, lobulated, and irregular nodules were more often malignant (52.2%, 100%, and 62.5%, respectively; p = 0.075). All nodules with smooth, well-defined margins were benign; those with spiculated or irregular borders were mostly malignant. Mean nodule diameter was 20.4 ± 5.2 mm. Lesions were more frequently located peripherally and in the upper lobes, with a right:left lung distribution of 55.1%:44.9% (p < 0.0001). Internal features included air lucency (23%), cavitation or calcification (9.8%), fat density (3.7%), necrosis (4.9%), and air-crescent sign (5.4%). Malignant nodules commonly exhibited spiculated margins and pleural tail sign (72.6%), while benign nodules showed smooth margins (90.9%). Delayed Phase CT yielded sensitivity 92.3%, specificity 94.8%, positive predictive value (PPV) 96.0%, negative predictive value (NPV) 90.2%, and overall accuracy 93.4%. Dynamic CT showed sensitivity 92.3%, specificity 71.4%, PPV 66.7%, NPV 93.7%, and accuracy 79.4%. Delayed Phase CT detected malignancy 1.95 times more frequently than Dynamic CT (p > 0.05). Conclusion: Solitary pulmonary nodules are common clinical findings with a substantial malignancy rate (48.5%). Delayed Phase CT provides critical information on nodule morphology, location, size, and contrast enhancement, significantly improving differentiation between benign and malignant SPNs.