| Purpose To determine the diagnostic value of dual-modality positron emission tomographic -computed tomographic (PET/CT) imaging, as compared with that of CT alone, PET alone and conventional visual correlation of CT and PET in the staging of non-small cell lung cancer (NSCLC).Materials and methods All consecutive seventy-eight patients underwent PET/CT scanning for the evaluation of possible NSCLC or health examination in our center during April 2003 to December 2003. All those patients underwent conventional thoracic CT before PET/CT imaging, and when necessary enhanced CT and high resolution CT of local pulmonary lesion is available. Abdominal and head CT scan are adopted when there is corresponding symptom in the patients. A diagnostic group (group A) performed blinded interpretation of CT alone, PET alone and visually correlated CT and PET sequentially for each case and obtained three diagnostic and staging conclusion. Similarly, blinded interpretation of PET alone, CT alone and dual-modality PET/CT was performed sequentially by another diagnostic group (group B). In those 78 patients, 60 were proved to be NSCLC (including 25 adenocarcinoma, 17 squamous carcinoma, 1 adenosquamous carcinoma, 2 large cell carcinoma and 15 lung cancer of uncertain histology type) and 18 were proved to be a benign process according to pathology or follow-up results. Group A correctly diagnosed 55 NSCLC according to CT, there are 5 false negative and 6 false positive cases in CT diagnosis. The diagnostic sensitivity, specificity, accuracy, positive predictive value and negative predictive value of CT is 91.7%(55/60), 66.7%(12/18), 85.9%(67/78), 90.2% (55/61) and 70.6%(12/17) respectively. 59 NSCLC were correctly diagnosed bygroup B according to PET, there are 1 false negative and 2 false positive cases in PET diagnosis. The diagnostic sensitivity, specificity, accuracy, positive predictive value and negative predictive value of PET is 98.3%(59/60), 88.9%(16/18), 96.2 %(75/78), 96.7%(59/61) and 94.1%(16/17) respectively. In those 60 NSCLC patients, five lost touch with us, so staging was studied in 55 patients. Overall stage was achieved in 55 patients. 19 patients underwent thoracotomy and obtained pathological T stage. N stage was surgically established in 23 cases. Tumor-node-metastasis (TNM) staging was deduced on the basis of image analysis and was scored according to our designed grading system. The standard of NSCLC staging is the International System for Staging Lung Cancer adopted by AJCC and UICC in 1997. Node stations were identified to the mapping system of the American Thoracic Society (ATS). We used a paired sign test to compare PET/CT and another three imaging modalities, which was completed in SPSS 11.5. To address the problem of multiple comparisons, Bonferroni's coreection was applied. Thus, P values less than 0.017 were considered to indicate statistical significance.Results Overall tumor stage was accurately classified with CT in 39 patients, with PET in 41 patients, with visual fusion in 45 patients and with PET/CT in 52 patients, equivocal in 9, 8, 4 and 0 patients respectively, incorrect in 7, 6, 4 and 3 patients. PET/CT findings were significantly more accurate when compared with CT alone findings (P<0.001), PET alone findings (P=0.001), or with visual fusion (P=0.016) in overall tumor staging. In overall tumor staging, the diagnostic accuracy of the four methods was 70.9%(39/55), 74.5%% (41/55 ), 84.9% (45/55) and 94.5% (52/55), respectively.PET/CT findings were significantly more accurate when compared with CT alone findings (P=0.016), PET alone findings (P=0.008), or with visual correlation of PET and CT (P=0.014) in T staging. The diagnostic accuracy of the fourmethods in T staging was 57.9%(11/19), 52.6%(10/19), 57.9%(11/19) and 94.7%(18/19) respectively.In nodal staging, PET/CT findings were significantly more accurate than CT alone (P=0.007) and were showed no significant difference with PET alone (P=0.25) and with visual correlation of PET and CT (P=0.25), but we found PET/CT helped...
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