Fig. 1Comparison of whole body maximum SUVs and regional maximum SUVs of 41 dissected malignant nodes and 29 dissected benign nodes which were visible on preoperative F-18 FDG PET.
Fig. 2Whole body F-18 FDG PET image (upper row) and delayed regional F-18 FDG PET image (lower row) of a 56-year-old man with adenocarcinoma in the upper lobe of the right lung. On the whole body PET image, only weak FDG accumulation was noted at 10R (right hilar) lymph node station; WB SUV was 1.33. On the regional PET image, however, FDG uptake was increased compared with the whole body PET image; Reg SUV was 2.39. Open thoracotomy biopsy revealed cancer cell invasion at this lymph node station.
Fig. 3Whole body F-18 FDG PET image (upper row) and delayed F-18 FDG PET image (lower row) of a 59-year-old man with squamous cell carcinoma in the middle lobe of the right lung. On the whole body PET image, FDG accumulation was noted at 4R (right lower paratracheal) lymph node station (arrows); WB SUV was 3.05. However, on the regional PET image, FDG uptake was decreased; Reg SUV was 2.57. Mediastinoscopic biopsy revealed no cancer cells in this lymph node. Dotted arrows show the 7 (subcarinal) lymph node station, which was invaded by cancer cells on mediastinoscopic biopsy. WB SUV was 3.08 and Reg SUV was 3.77.
Fig. 4(A) Plot of WB SUVs of 41 visible malignant nodes and 29 visible benign nodes (left) and ROC curve of WB SUVs (right). For a cut-off value of 2.89 WB SUV, the sensitivity was 80.5% and the specificity 82.8%. (B) Plot of Reg SUVs of the same nodes (left) and the ROC curve of Reg SUVs (right). For a cut-off value of 3.61 Reg SUV, the sensitivity was 87.8% and the specificity 82.8%. (C) Plot of percent change of SUVs (% SUV Changes) of the same nodes (left) and the ROC curve of % SUV Changes (right). For a cut-off value of 12.3 % SUV Change, the sensitivity was 87.8% and the specificity 41.4.
Fig. 5(A) Correlation between WB SUVs and % SUV Changes of 41 dissected malignant nodes which were visible on FDG PET. Although there was a trend toward negative correlation, it did not reach statistical significance (r=-0.30, p=0.057). (B) Correlation between WB SUVs and % SUV Changes of 82 malignant primary lung lesions. A significant negative correlation was found (r=-0.38, p=0.0005).
Table 1Patient characteristics
Table 2Diagnostic performance of F-18 WB FDG PET on visualizing malignant lymph nodes of 290 dissected lymph node stations
Table 3Comparison of mean values of WB SUV, Reg SUV, and % SUV change between benign nodes and malignant nodes which were visible on F-18 whole body FDG PET scan
Table 4Correlation analyses between WB SUVs and % SUV Changes of visible benign nodes, visible malignant nodes and malignant primary lung lesions