Characterization of pulmonary nodules and mediastinal staging of bronchogenic carcinoma with F-18 fluorodeoxyglucose positron emission tomography.

OBJECTIVE

To evaluate F-18 fluorodeoxyglucose positron emission tomography (PET) in terms of its sensitivity and specificity in diagnosing malignant pulmonary nodules and staging bronchogenic carcinoma.

METHODS

A retrospective review of any patient that presented to the VA Palo Alto Health Care System with a pulmonary nodule between 9/94 and 3/96 revealed 49 patients (four female, 45 male) age 37-85 (mean 63) with 54 pulmonary nodules who had: chest CT scan, PET scan; and tissue characterization of the nodule. Characterization of each nodule was achieved by histopathologic (N = 44) or cytopathologic (N = 10) analysis. Of the 49 patients, 18 had bronchogenic carcinoma which was adequately staged. Mediastinal PET and CT findings in these 18 patients were compared with the surgical pathology results. N2 disease was defined as mediastinal lymph node involvement by the American Thoracic Society's classification system. Mediastinal lymph nodes were interpreted as positive by CT if they were larger that 1.0 cm in the short-axis diameter.

RESULTS

Sensitivity and specificity for the diagnosis of malignant pulmonary nodules using PET was 93 and 70%, respectively. All nodules (N = 3) that were falsely positive by PET scan were infectious in origin. All nodules (N = 4) that were falsely negative by PET were technically limited studies (outdated scanner, no attenuation correction, hyperglycemia) except for one case of metastatic adenocarcinoma. The sensitivity and specificity of PET in diagnosing N2 disease was 67 and 100%, compared with 56% and 100% for CT scan (not statistically significant). However, one more patient with N2 disease was correctly diagnosed by PET than by CT scan.

CONCLUSION

PET is a valuable tool in the diagnosis and management of pulmonary nodules and may more accurately stage patients with bronchogenic carcinoma than CT scanning alone.