Value of Dual-Time-Point FDG PET/CT for Mediastinal Nodal Staging in Non-Small-Cell Lung Cancer Patients With Lung Comorbidity

Purpose: To evaluate the efficacy of dual-time-point F-18 fluorodeoxyglucose positron emission tomography (FDG PET)/ computed tomography (CT) for mediastinal nodal staging in non-small-cell lung cancer patients with lung comorbidity. Materials and Methods: Fifty-three pathologically proven non-small-cell lung cancer patients with pulmonary comorbidity and 49 patients as controlled group without comorbidity were enrolled. PET/CT was performed at 1-hour (whole body) post-FDG injection and repeated 2 hours (thoracic) after injection. All patients received radical surgery with system mediastinal lymph node (LN) dissection. The results of LN detection by single-time-point and dual-time-point scan were compared with the histopathologic findings. Results: On a per-patient basis, in patients with pulmonary comorbidity, the sensitivity, specificity, accuracy, and positive predictive values (PPV), and negative predictive values of single-time-point scan were 87.5%, 59.5%, 67.9%, 48.3%, and 91.7%, respectively. Those values of dual-time-point scan were 93.8%, 67.6%, 75.5%, 55.6%, and 96.2%, respectively. In patients without comorbidity, dual-time-point scan was similar in those values to single-time-point. On a per-nodal station basis, the specificity, accuracy, and PPV of dual-time-point scan were better than those of single-time-point with statistically significant differences (P = 0.017, 0.002, and 0.027, respectively) in patients with pulmonary comorbidity, but the difference was not statistically significant in patients with no pulmonary comorbidity. Conclusions: Dual-time-point FDG PET/CT is more effective for mediastinal nodal staging than single-time-point in patients with pulmonary comorbidity. Dual-time-point scan was useful for diagnosis of mediastinal LN metastases in reducing the false-positive results in all patients, but improved specificity, accuracy, and PPV only in patients with pulmonary comorbidity.