Features of non-malignant thoracic lesions on F-18 FDG PET/CT scan

Abstract

Introduction: During PET/CT chest interpretation, the radiologist may encounter non-malignant positive findings originating from physiologic variants, inflammation, infection, iatrogenic causes, post-surgical/post-therapeutic changes and benign tumors of different components of the thorax.  This article illustrates and raises the awareness of these benign FDG-avid findings.

Methods: We use a search engine to retrospectively review the 10-year PET/CT and pathology database of our institution for cases with thoracic findings linked to physiologic variations, and to benign processes and diseases. The keywords used for the search include all the entities presented in this article. We select the cases presenting with the most didactic value of benignity related to (1) established imaging patterns already published in the literature, which serves as reference articles in this paper, (2) final diagnosis from tissue sampling of ambiguous and difficult cases, and (3) long term monitoring based on clinical evaluation and anatomic and functional imaging.

Results: Among the pool of cases fulfilling the required search criteria, we choose the most illustrative ones to present the different categories of benign findings encompassing the physiologic variants, inflammation, infection, iatrogenic causes, post-operative and post-therapeutic changes, and benign neoplasms. The most representative reference articles of the presented cases concerning all the benign thoracic entities are selected for the bibliography.

Conclusion: The presented PET/CT cases raise the awareness and strengthen the interpretation confidence of the radiologist during the evaluation of cancer. The familiarity with these benign thoracic entities would obviate any suspicion of malignancy and avoid unnecessary additional assessment using expansive and potentially harmful procedures.