Eun Ju Chun MD, Presenter: Nothing to Disclose

Hyun Ju Lee MD, PhD, Abstract Co-Author: Nothing to Disclose

Won Joon Kang, Abstract Co-Author: Nothing to Disclose

Chang Hyun Lee MD, Abstract Co-Author: Nothing to Disclose

Chang Min Park MD, Abstract Co-Author: Nothing to Disclose

Jin Mo Goo MD, PhD, Abstract Co-Author: Nothing to Disclose

Jung-Gi Im MD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To assess whether we can differentiate nodular ground-glass opacities (NGGOs) on chest CT as a malignant tumor or as an inflammatory nodule using FDG integrated PET/CT

36 patients (M:F=21:15; mean age 63 years) who had a NGGO on chest CT performed integrated PET/CT. The NGGO was defined as the round shaped GGO smaller than 3 cm. The size of the lesions was 8-30mm (mean, 14.8mm). Among total of 59 NGGOs, 14 were pure GGOs, and 45 were mixed GGOs. 37 malignant NGGOs were pathologically adenocarcinoma (n=11), bronchioloalveolar carcinoma (n=10), metastasis (n=8) and low-grade lymphoma (n=8). 22 inflammatory NGGOs were confirmed as pneumonic infiltration because they disappeared on the follow-up CT and well-matched clinical features (n=18) or as chronic inflammation with fibrosis by VATS biopsy (n=4). The PET/CT were assessed by measuring a maximum standardized uptake value (max SUV) that was obtained on the region of interest locating at each NGGO. Mann-Whitney U test was performed to compare the max SUV in malignant NGGOs with inflammatory NGGOs. The optimal cut-off value of max SUV to differentiate malignancy from inflammation was determined by using a receiver operating characteristic–based positive test. Sensitivity, specificity, PPV, NPV, and accuracy were all calculated at the level of the optimal cut-off value. The max SUV showing 100% PPV for inflammatory nodule was evaluated.

The max SUV of inflammatory NGGOs (range, 0.44-3.12; mean±SD, 1.39±0.76) was significantly higher than that of malignant NGGOs (0.30-2.50; 1.07±0.60) (p< 0.05). The optimal cut-off value of max SUV was 1.27 (p=0.0366). Sensitivity, specificity, PPV, NPV, and accuracy were 78%, 59%, 76%, 62%, and 63%, respectively. At cut-off value of 2.5, PPV for inflammatory NGGOs was 100%.

The max SUV of the inflammatory NGGOs were higher than that of malignant NGGOs. This is a paradoxical result compared to the basic knowledge that the malignant lesion has a higher glucose metabolism. Moreover, NGGO with max SUV higher than 2.5 has a high possibility of inflammation.

Integrated PET/CT can help differentiate between inflammatory and malignant lesions in patients with NGGO.

Chun, E, Lee, H, Kang, W, Lee, C, Park, C, Goo, J, Im, J, et al, , Can Integrated PET/CT Using Fluorodeoxyglucose (FDG) Differentiate the Malignant Tumor from Inflammatory Nodule on Nodular Ground-Glass Opacity?.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4440189.html