Accuracy of Helical Computed Tomography and [18F] Fluorodeoxyglucose Positron Emission Tomography for Identifying Lymph Node Mediastinal Metastases in Potentially Resectable Non–Small-Cell Lung Cancer

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Abstract
Purpose: Computed tomography (CT) and [18F] Fluorodeoxyglucose positron emission tomography (FDG-PET) are considered suitable methods for the noninvasive staging of the mediastinum. Our study was intended to estimate the efficacy of contrast-enhanced helical CT (hCT) and FDG-PET, alone and combined, in the diagnosis of lymph node mediastinal metastases. Methods: This study was a prospective and blind comparison of the efficacy of hCT and FDG-PET with two alternative reference standards, mediastinoscopy, and mediastinoscopy plus thoracotomy plus a 6-month follow-up to diagnose lymph node mediastinal metastases in 132 consecutive patients with potentially resectable non–small-cell lung cancer (NSCLC). The metastatic disease was assessed histopathologically. Further clinical information was obtained postoperatively after a median follow-up of 42 months. Results: The prevalence of cN2,3 is 0.28. For hCT the sensitivity and specificity are 0.86 (95% CI, 0.70 to 0.93) and 0.67 (95% CI, 0.56 to 0.75), for PET 0.94 (95% CI, 0.81 to 0.98) and 0.59 (95% CI, 0.49 to 0.68), and for hCT and PET combined in-parallel 0.97 (95% CI, 0.84 to 0.99) and 0.44 (95% CI, 0.34 to 0.53), which translate into a negative predicted probability of 0.98 (95% CI, 0.88 to 1.00). The crude diagnostic odds ratio of PET in the total sample studied is 13.1, in the subgroup hCT+ 11.04 (3.0 to 40 0.1), and in the hCT- 3.5 (0.5 to 21.5). Similar results were obtained for hCT stratified by PET. Conclusion: hCT and PET perform similarly in the mediastinal staging of NSCLC, both tests are conditionally dependent and provide complementary information, and their diagnostic value mainly resides on the negative results.