18F-FDG PET for the lymph node staging of non-small cell lung cancer in a tuberculosis-endemic country: Is dual time point imaging worth the effort?

Purpose: This study was to compare 18F-FDG positron emission tomography (PET) with thoracic contrast-enhanced CT (CECT) in the ability of lymph node (LN) staging non-small cell lung cancer (NSCLC) in a tuberculosis-prevalent country. The usefulness of dual time point PET imaging (DTPI) in NSCLC nodal staging was also evaluated. Methods: We reviewed 96 NSCLC patients (mean age, 65.3 ± 11.7 years) who had received PET studies before their surgery. DTPI were performed on 37 patients (mean age, 64.8 ± 12.2 years) who received an additional scan of thorax 3 h after tracer injection. The accuracies of nodal staging by CECT and PET were evaluated according to final histopathology of hilar and mediastinal LN resected by surgery. Results: The accuracy for nodal staging by CECT was 65.6% and that by PET was 82.3% (p < 0.05). Six patients were over-staged and 11 were under-staged by PET. Tuberculosis (n = 3, 50%) were mostly responsible for false-positive, while small tumor foci (n = 7, 63.6%) were mostly accountable for false-negative. For the 37 patients with DTPI, 45 min standardized uptake value (SUV) and 3 h SUV for negative LNs are significantly lower than those for positive LNs (p < 0.0001). Nevertheless, the retention index (RI) showed no significant difference between these two groups. Conclusions: Our study demonstrates that PET is more accurate than CECT in LN staging NSCLC patients in Taiwan where TB is still prevalent. Semi-quantitative SUV method or DTPI with RI does not result in better diagnostic accuracy than visual analysis of PET images. ? 2008 Springer-Verlag.