BACKGROUND: (18)F-FDG PET/CT has been used to differentiate malignant solid lung nodules from benign nodules. We assess the feasibility of integrated (18)F-FDG PET/CT for the differentiation of malignancy from inflammation manifested as ground-glass nodules (GGNs) on chest CT. METHODS: A total of 68 GGNs in 45 patients (M:F=24:21; mean age, 61) fulfilled the following criteria: (a) nodules composed of >/=50% ground-glass opacity, (b) patients who underwent integrated PET/CT within 1 week following dedicated chest CT, (c) definitive diagnosis determined by pathological specimen or at least 9 months of follow-up, and (d) lesions >/=10mm in diameter. 36 malignant GGNs were pathologically proved as adenocarcinoma (n=20), bronchioloalveolar carcinoma (n=11), low-grade lymphoma (n=3), metastatic mucinous adenocarcinoma (n=1) and unknown low-grade malignancy (n=1). 32 inflammatory GGNs were confirmed as pneumonic infiltration as they had disappeared on follow-up CT and were associated with compatible clinical features (n=26) or as chronic inflammation with fibrosis by VATS biopsy (n=6). Using CT density histogram analysis, 14 were classified as pure GGNs and 54 as part-solid nodules. Integrated PET/CT was evaluated by measuring the maximum standardized uptake value (SUV) at the region of interest located at each lesion. The Mann-Whitney U test was performed to compare the SUV of malignancy and inflammation. The optimal cut-off value of SUV to differentiate malignancy from inflammation was determined using a receiver operating characteristic-based positive test. Sensitivity, specificity, accuracy, and positive predictive values (PPV) and negative predictive values (NPV) were calculated at the level of the optimal cut-off value. SUV showing 100% PPV for inflammatory GGNs was evaluated. RESULTS: In part-solid nodules, the maximum SUV was significantly higher in inflammation (2.00+/-1.18; range, 0.48-5.60) than in malignancy (1.26+/-0.71; range, 0.32-2.6) (P=0.018). On the other hand, in pure GGNs, the maximum SUV of malignancy (0.64+/-0.19; range, 0.43-0.96) and inflammation (0.74+/-0.28; range, 0.32-1.00) showed no difference (P=0.37). Using the optimal cut-off value of SUV as 1.2 (P=0.01) sensitivity, specificity, accuracy, PPV and NPV in part-solid nodules were 62.1%, 80.0%, 70.4%, 78.3% and 64.5%, respectively. Six part-solid nodules, which showed a maximum SUV of higher than 2.6, were all inflammations. CONCLUSION: The part-solid nodules with positive FDG-PET could be inflammatory nodules rather than malignant nodules. This is a quite paradoxical result when considering the basic knowledge that malignant pulmonary nodules have higher glucose metabolism.
BACKGROUND: (18)F-FDG PET/CT has been used to differentiate malignant solid lung nodules from benign nodules. We assess the feasibility of integrated (18)F-FDG PET/CT for the differentiation of malignancy from inflammation manifested as ground-glass nodules (GGNs) on chest CT. METHODS: A total of 68 GGNs in 45 patients (M:F=24:21; mean age, 61) fulfilled the following criteria: (a) nodules composed of >/=50% ground-glass opacity, (b) patients who underwent integrated PET/CT within 1 week following dedicated chest CT, (c) definitive diagnosis determined by pathological specimen or at least 9 months of follow-up, and (d) lesions >/=10mm in diameter. 36 malignant GGNs were pathologically proved as adenocarcinoma (n=20), bronchioloalveolar carcinoma (n=11), low-grade lymphoma (n=3), metastatic mucinous adenocarcinoma (n=1) and unknown low-grade malignancy (n=1). 32 inflammatory GGNs were confirmed as pneumonic infiltration as they had disappeared on follow-up CT and were associated with compatible clinical features (n=26) or as chronic inflammation with fibrosis by VATS biopsy (n=6). Using CT density histogram analysis, 14 were classified as pure GGNs and 54 as part-solid nodules. Integrated PET/CT was evaluated by measuring the maximum standardized uptake value (SUV) at the region of interest located at each lesion. The Mann-Whitney U test was performed to compare the SUV of malignancy and inflammation. The optimal cut-off value of SUV to differentiate malignancy from inflammation was determined using a receiver operating characteristic-based positive test. Sensitivity, specificity, accuracy, and positive predictive values (PPV) and negative predictive values (NPV) were calculated at the level of the optimal cut-off value. SUV showing 100% PPV for inflammatory GGNs was evaluated. RESULTS: In part-solid nodules, the maximum SUV was significantly higher in inflammation (2.00+/-1.18; range, 0.48-5.60) than in malignancy (1.26+/-0.71; range, 0.32-2.6) (P=0.018). On the other hand, in pure GGNs, the maximum SUV of malignancy (0.64+/-0.19; range, 0.43-0.96) and inflammation (0.74+/-0.28; range, 0.32-1.00) showed no difference (P=0.37). Using the optimal cut-off value of SUV as 1.2 (P=0.01) sensitivity, specificity, accuracy, PPV and NPV in part-solid nodules were 62.1%, 80.0%, 70.4%, 78.3% and 64.5%, respectively. Six part-solid nodules, which showed a maximum SUV of higher than 2.6, were all inflammations. CONCLUSION: The part-solid nodules with positive FDG-PET could be inflammatory nodules rather than malignant nodules. This is a quite paradoxical result when considering the basic knowledge that malignant pulmonary nodules have higher glucose metabolism.
Authors: Karen P Chu; James D Murphy; Trang H La; Trevor E Krakow; Andrei Iagaru; Edward E Graves; Annie Hsu; Peter G Maxim; Billy Loo; Daniel T Chang; Quynh-Thu Le Journal: Int J Radiat Oncol Biol Phys Date: 2012-01-21 Impact factor: 7.038
Authors: Sang Min Lee; Chang Min Park; Jin Chul Paeng; Hyung Jun Im; Jin Mo Goo; Hyun-Ju Lee; Chang Hyun Kang; Young Whan Kim; Jung Im Kim Journal: Eur Radiol Date: 2012-02-24 Impact factor: 5.315
Authors: Michael K Gould; Jessica Donington; William R Lynch; Peter J Mazzone; David E Midthun; David P Naidich; Renda Soylemez Wiener Journal: Chest Date: 2013-05 Impact factor: 9.410