Diagnostic efficacy of PET-FDG imaging in solitary pulmonary nodules. Potential role in evaluation and management.

BACKGROUND: Positron emission tomography (PET), a new noninvasive imaging modality, utilizing 2-[F-18]-fluoro-2-deoxy-D-glucose (FDG), has demonstrated increased FDG uptake in lung tumors. OBJECTIVE: To determine the diagnostic efficacy of PET-FDG imaging in differentiating benign from malignant solitary pulmonary nodules. PATIENT SELECTION: A prospective study of 30 patients who presented with indeterminate solitary pulmonary nodules less than 3 cm in size based on chest radiograph and computed tomographic (CT) scan. SETTING: Two tertiary care medical centers in Omaha, Neb: Creighton University Medical Center and the Omaha Veterans Administration Medical Center. MEASUREMENTS: Positron emission tomographic imaging of the lung was performed 1 h after intravenous injection of 10 mCi of F-18-FDG. Qualitative analysis of the images was performed independently by two observers by visual identification of the areas of increased FDG uptake in the lung nodules. Semiquantitative analysis was performed using computation of differential uptake ratio (DUR). Histologic specimens were obtained in 29 patients (thoracotomy 20, transthoracic needle aspiration biopsy 8, bronchoscopy 1). RESULTS: Positron emission tomographic imaging correctly identified 27 of 30 pulmonary nodules. Diagnostic accuracy was high with sensitivity of 95 percent and specificity of 80 percent. The positive and negative predictive value of PET imaging for solitary pulmonary nodules was 90 percent and 89 percent, respectively. The DUR values were significantly higher for malignant nodules (mean +/- SD, 5.55 +/- 2.79) than benign nodules (mean +/- SD, 0.95 +/- 0.99) (p < 0.001). There was one false-negative result in a patient with a 1-cm nodule identified as a scar adenocarcinoma. There were two false-positive cases and both had caseating granulomas with active inflammation and Histoplasma organisms. CONCLUSION: PET-FDG imaging of the lung, a new noninvasive diagnostic test, has a high degree of accuracy in differentiating benign from malignant pulmonary nodules. PET-FDG imaging could complement CT scanning in the evaluation and treatment of patients with solitary pulmonary nodules.

Solitary pulmonary nodules: detection of malignancy with PET with 2-[F-18]-fluoro-2-deoxy-D-glucose.

It is estimated that nearly one-third of solitary pulmonary nodules (SPNs) may represent bronchogenic carcinoma. The noninvasive imaging methods used currently (ie, plain radiography, computed tomography) are not reliable for accurate detection of malignancy in most SPNs. The authors prospectively evaluated use of positron emission tomography (PET) with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) for identification of malignancy in 20 patients with noncalcific, radiographically indeterminate SPNs. PET-FDG imaging demonstrated focal hypermetabolism in 13 biopsy-proved malignant nodules, whereas no increased FDG uptake was seen in the seven benign SPNs. Semiquantitative analysis with computation of differential uptake ratios also helped clearly differentiate benign nodules (mean +/- standard deviation, 0.56 +/- 0.27) from malignant nodules (mean +/- standard deviation, 5.63 +/- 2.38) (P less than .001). Thus, PET-FDG imaging may be a potentially useful noninvasive technique for accurate differentiation of benign and malignant SPNs that are radiographically indeterminate.