Pulmonary nodule detection with low-dose ionizing-radiation CT compared to chest X-ray for follow-up of non-pulmonary malignancies

Abstract

Introduction. The follow-up of patients with extrapulmonary malignancies includes imaging studies to detect metastatic pulmonary nodules. This study compared pulmonary nodule detection with chest X-ray (CXR) and low-dose computed tomography (LDCT) in patients with a follow-up protocol for extrapulmonary malignancies. Material and Methods. This comparative cross-sectional study was conducted in oncologic referral patients with extrapulmonary malignancies initiating a follow-up protocol. All patients underwent posteroanterior CXR (100-110 kVp, 4-8 mAs) followed by chest LDCT (120 kVp, 100 mA, 34 mAs). Pulmonary nodules, their location, size, and density were recorded. The sensitivity and specificity of CXR were calculated using chest LDCT as the gold standard. Results. Forty-six patients underwent CXR and chest LDCT. Forty-three nodules were detected on CXR compared to 101 on chest LDCT; thus, 58 (57.4%) pulmonary nodules remained undetected on CXR. Smaller pulmonary nodules were detected on LDCT with a mean of 5.7 ± 4.6 mm and on CXR with 7.1 ± 6.1 mm. Most pulmonary nodules were detected in zone 2, or the peripheral lung parenchyma, and in the right lung. Sensitivity was 56.7% (95% CI, 37.4-74.5), and specificity was 93.75% (95% CI, 69.8-99.8) for CXR nodule detection. Conclusion. LDCT had a higher pulmonary nodule detection rate than CXR, regardless of location, size, and nodule density. This study is the first in Mexico to compare LDCT with CXR for the detection of pulmonary nodules in patients with extrapulmonary malignancy follow- up.

Keywords

• Tumor follow-up. Extrapulmonary Malignancy. Pulmonary nodule. Low-dose CT. Chest radiograph.