**5. Conclusions**

In conclusion, our study enabled the selection of some RF that are able to predict with a certain good accuracy, the final nature of TIs discovered at 18F-FDG PET/CT imaging. Classic semiquantitative and volumetric PET/CT parameters did not reveal this ability. Furthermore, a good overlap in the extraction of RF between the two scanners was underlined.

**Author Contributions:** Conceptualization, F.D., R.G. (Roberto Gattaand) and D.A.; methodology, R.G. (Raffaele Giubbini) and N.P.; formal analysis, F.D. and R.G. (Roberto Gattaand); writing—original draft preparation, F.D., D.A. and R.G. (Raffaele Giubbini); writing—review and editing, N.P. and F.B. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Ethical review and approval were waived for this study due to the retrospective design of the study according to the local laws.

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** Data are not public, but are present in our institution.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

