Improving Diagnostic Accuracy for Malignant Nodes and N Staging in Non-Small Cell Lung Cancer Using CT-Corrected FDG-PET / 대한핵의학회잡지

ABSTRACT

PURPOSE: We investigated prospectively whether the interpretation considering the patterns of FDG uptake and the findings of unenhanced CT for attenuation correction can improve the diagnostic accuracy for assessing malignant lymph node (LN) and N stage in non-small cell lung cancer (NSCLC) using CT-corrected FDG-PET (PET/CT). MATERIALS AND METHODS: Subjects were 91 NSCLC patients (M/F 62/29, age 60+/-9 yr) who underwent PET/CT before LN dissection. We evaluated the maximum SUV ( (max) SUV), patterns of FDG uptake, short axis diameter, and calcification of LN showing abnormally increased FDG uptake. Then we investigated criteria improving the diagnostic accuracy and correlated results with postoperative pathology. In step 1, LN was classified as benign or malignant based on (max) SUV only. In step 2, LN was regarded as benign if it had lower (max) SUV than the cut-off value of step 1 or it had calcification irrespective of its (max) SUV. In step 3, LN regarded as malignant in step 2 was classified as benign if they had indiscrete margin of FDG uptake. RESULTS: Among 432 LN groups surgically resected (28 malignant, 404 benign), 71 showed abnormally increased FDG uptake. We determined the cut-off as (max) SUV = 3.5 using ROC curve analysis. The sensitivity, specificity, and accuracy for assessing malignant LN were 64.3%, 86.9%, 85.4% in step 1, 64.3%, 95.0%, 93.1% in step 2, and 57.1%, 98.0%, 95.4% in step3, respectively. The accuracy for assessing N stage was 64.8% in step 1, 80.2% in step 2, and 85.7% in step 3. CONCLUSION: Interpreting PET/CT, consideration of calcification and shape of the FDG uptake margin along with (max) SUV can improve the diagnostic accuracy for assessing malignant involvement and N stage of hilar and mediastinal LNs in NSCLC.