Background: Integrated (18)fluorine fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) has shown somewhat variable sensitivity and specificity for mediastinal nodal staging in granulomatous disease endemic areas. The purpose of the study was to prospectively evaluate the efficacy of PET/CT for mediastinal nodal staging in nonsmall cell lung cancer (NSCLC) patients in a tuberculosis-endemic country.
Methods: Prospective assessment of the diagnostic efficacy of integrated PET/CT for detecting mediastinal nodal metastasis was performed in 674 patients (M:F ratio = 502:172; mean age, 61 years) with NSCLC. Patients underwent an integrated PET/CT examination and subsequent surgical nodal staging (by mediastinoscopy only in 121 patients and by thoracotomy in 553). Nodes showing greater (18)F-FDG uptake than mediastinum at PET without benign calcification or high attenuation >70 household unit (HU) at unenhanced CT were regarded as being positive for malignancy. The histologic nodal assessment results were used as reference standards.
Results: Of 2477 mediastinal nodal stations evaluated in 674 patients, 275 (11%) stations in 180 (27%) patients proved to be malignant. On a per-person basis, the overall sensitivity, specificity, and accuracy of PET/CT for mediastinal nodal staging were 61% (110 of 180), 96% (473 of 494), and 86% (583 of 674), respectively. On a per-nodal station basis, they were 46% (126 of 275), 98% (2154 of 2202), and 92% (2280 of 2477).
Conclusions: Integrated PET/CT provides high specificity and reasonably high accuracy, but somewhat low sensitivity for mediastinal nodal staging of NSCLCs. The high specificity is achieved at the expense of sensitivity by interpreting calcified nodes or nodes with high attenuation at CT, even with high FDG uptake at PET, as benign in a tuberculosis-endemic region.