The Role of 18F-FDG PET/CT Integrated Imaging in Distinguishing Malignant from Benign Pleural Effusion

Our plain-English summary of The Role of 18F-FDG PET/CT Integrated Imaging in Distinguishing Malignant from Benign Pleural Effusion, by Y. Sun, H. Yu, J. Ma, et al (PloS One, 2016).

The study

• Authors: Y. Sun, H. Yu, J. Ma, P. Lu
• Journal: PloS One
• Published: 2016;11(8):e0161764
• Cited by: 37 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objective: The aim of our study was to evaluate the role of 18F-FDG PET/CT integrated imaging in differentiating malignant from benign pleural effusion.

Methods: A total of 176 patients with pleural effusion who underwent 18F-FDG PET/CT examination to differentiate malignancy from benignancy were retrospectively researched. The images of CT imaging, 18F-FDG PET imaging and 18F-FDG PET/CT integrated imaging were visually analyzed. The suspected malignant effusion was characterized by the presence of nodular or irregular pleural thickening on CT imaging. Whereas on PET imaging, pleural 18F-FDG uptake higher than mediastinal activity was interpreted as malignant effusion. Images of 18F-FDG PET/CT integrated imaging were interpreted by combining the morphologic feature of pleura on CT imaging with the degree and form of pleural 18F-FDG uptake on PET imaging.

Results: One hundred and eight patients had malignant effusion, including 86 with pleural metastasis and 22 with pleural mesothelioma, whereas 68 patients had benign effusion. The sensitivities of CT imaging, 18F-FDG PET imaging and 18F-FDG PET/CT integrated imaging in detecting malignant effusion were 75.0%, 91.7% and 93.5%, respectively, which were 69.8%, 91.9% and 93.0% in distinguishing metastatic effusion. The sensitivity of 18F-FDG PET/CT integrated imaging in detecting malignant effusion was higher than that of CT imaging (p = 0.000). For metastatic effusion, 18F-FDG PET imaging had higher sensitivity (p = 0.000) and better diagnostic consistency with 18F-FDG PET/CT integrated imaging compared with CT imaging (Kappa = 0.917 and Kappa = 0.295, respectively). The specificities of CT imaging, 18F-FDG PET imaging and 18F-FDG PET/CT integrated imaging were 94.1%, 63.2% and 92.6% in detecting benign effusion. The specificities of CT imaging and 18F-FDG PET/CT integrated imaging were higher than that of 18F-FDG PET imaging (p = 0.000 and p = 0.000, respectively), and CT imaging had better diagnostic consistency with 18F-FDG PET/CT integrated imaging compared with 18F-FDG PET imaging (Kappa = 0.881 and Kappa = 0.240, respectively).

Conclusion: 18F-FDG PET/CT integrated imaging is a more reliable modality in distinguishing malignant from benign pleural effusion than 18F-FDG PET imaging and CT imaging alone. For image interpretation of 18F-FDG PET/CT integrated imaging, the PET and CT portions play a major diagnostic role in identifying metastatic effusion and benign effusion, respectively.

In plain English

This retrospective study, from the Affiliated Tumor Hospital of Harbin Medical University in China, looked at 176 patients with fluid around the lungs (pleural effusion) who had an 18F-FDG PET/CT scan between June 2005 and May 2013. The article does not report on asbestos exposure. The authors compared how well CT images, PET images, and combined PET/CT images told cancer-related fluid from non-cancer fluid. Of the 176 patients, 108 had malignant effusion (22 from pleural mesothelioma and 86 from cancer that had spread to the pleura) and 68 had benign effusion. Combined PET/CT correctly identified 93.5% (101/108) of malignant effusions, compared with 75.0% for CT and 91.7% for PET. For the 22 mesothelioma cases, the share of cases each method detected did not differ statistically among the three methods. Combined PET/CT correctly identified 92.6% (63/68) of benign effusions, compared with 94.1% for CT and 63.2% for PET. PET wrongly flagged 17 of 30 tuberculous effusions as malignant. The authors concluded that combined PET/CT was more reliable than either scan alone. They noted that CT was done without contrast dye, which may have affected how well CT performed.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: retrospective diagnostic accuracy study comparing CT, 18F-FDG PET and combined PET/CT against pathology and clinical findings
• Who was studied: 176 patients with pleural effusion (108 men, 68 women, aged 35 to 92) who had 18F-FDG PET/CT at the Affiliated Tumor Hospital of Harbin Medical University, Harbin, China, June 2005 to May 2013
• Exposure: No asbestos or fiber exposure is reported. What the study compared was the imaging method: CT alone, 18F-FDG PET alone, and combined PET/CT, each judged against pathology and clinical findings.
• Main results:
  • Of 176 patients, 108 had malignant effusion (86 pleural metastasis, 22 pleural mesothelioma) and 68 had benign effusion
  • CT alone detected 75.0% (81/108) of malignant effusions
  • PET alone detected 91.7% (99/108) of malignant effusions
  • Combined PET/CT detected 93.5% (101/108) of malignant effusions
  • For effusions caused by pleural mesothelioma (22 patients), there was no statistical difference in sensitivity among CT, PET and PET/CT (p = 1.000 for each comparison)
  • CT alone correctly identified 94.1% of the 68 benign effusions (64 patients)
  • PET alone correctly identified 63.2% (43/68) of benign effusions
  • Combined PET/CT correctly identified 92.6% (63/68) of benign effusions
  • On PET imaging, 56.7% (17/30) of tuberculous pleural effusions gave false-positive findings
• The authors' conclusion: The authors concluded that combined 18F-FDG PET/CT was a more reliable way to tell malignant from benign pleural effusion than PET or CT alone. In their view, the PET portion played the main role in identifying metastatic effusion and the CT portion in identifying benign effusion.
• Limitations the authors state:
  • CT was performed without contrast. The authors state that contrast-enhanced CT is better at separating pleural thickening from fluid, so this may have affected CT's performance.
  • Diagnosis was based only on abnormalities of the pleura, not on FDG uptake in the fluid itself, which the authors say may be useful

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Pleural Effusion, Pleural Thickening, Pleura, Metastasis, Pleural Mesothelioma.

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