Abstract
ObjectiveTo determine the diagnostic efficacy of 18F‐FDG PET/CT in distinguishing between pulmonary tuberculosis (PTB) and lung cancer in solitary pulmonary nodule (SPN) in a country with a high prevalence of PTB.MethodsPatients with SPN who underwent 18F‐FDG PET/CT imaging were retrospectively included in the study. The final diagnosis was established by histopathology. A linear regression equation was fitted to a scatter plot of size and SUVmax of lung cancer and PTB. ROC was used to determine the optimal cutoff values and diagnostic accuracy of 18F‐FDG PET/CT in PTB and lung cancer.ResultsAbout 514 patients were included with the mean age of 57.5 ± 10.6 years. Four hundred and seventy‐five cases were diagnosed as lung cancer, and 39 cases were PTB by histopathology. 18F‐FDG PET/CT had sensitivity, specificity, and diagnostic accuracy of 96.0%, 48.7%, and 92.0%, respectively. Utilization of SUVmax ≥2.5 in SPN resulted in 2 and 11 false positives cases of lung cancer and PTB, respectively, whereas SUVmax <2.5 resulted in 18 and 10 false‐positive cases of lung cancer and PTB, respectively. The SUVmax and the size of short‐axis in the lung cancer group were statistically higher than those in the PTB group. The linear regression equation parameters indicated the slope of the regression line of lung cancer was greater than that of PTB. The ROC curve demonstrated the SUVmax cutoff values of 4.85 and 2.25 for lung cancer and PTB, respectively for predicting the diagnostic accuracy of 18F‐FDG PET/CT.Conclusion 18F‐FDG PET/CT has a higher sensitivity and diagnostic accuracy for malignant SPN. However, it has high false‐positive rate and low specificity in tuberculosis endemic areas. Neither SUVmax nor the sizes of the nodules are valuable parameters for distinguishing between lung cancer and PTB. However, the SPN with larger short‐axis and higher SUVmax would be inclined to malignant tumor.
Highlights
Lung cancer is a leading cancer-related death because of its high morbidity and mortality.[1,2,3] Molecular/anatomic imaging with 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) has been well recognized as an important tool for detecting, identifying, and staging lung cancer
Statistically significant differences could be seen in age (P = .0017), Maximum Standardized Uptake value (SUVmax) (P = .0001) and short-axis diameter (P = .0045) when comparing lung cancer and pulmonary tuberculosis (PTB)
From the Receiver operating characteristics (ROC) curves (Figure 3), the cutoff value for positive 18F-FDG PET/CT lung cancer was 4.85 with sensitivity, specificity, and area under the curve (AUC) of 72.0%, 85.0%, and 0.827, respectively
Summary
Lung cancer is a leading cancer-related death because of its high morbidity and mortality.[1,2,3] Molecular/anatomic imaging with 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) has been well recognized as an important tool for detecting, identifying, and staging lung cancer. It provides metabolic information, which allows readers to distinguish between benign and malignant tissue. Some types of cancer, such as carcinoid tumors[14] and bronchoalveolar carcinoma (adenocarcinoma in situ)[15] have low 18F-FDG uptake, which can lead to false-negative results
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