Fig. 4

Comparison of PET/CT fusion imaging, R-signature, and histopathology for FL (I, II, and IIIa grades) and t-FL. A I Grade FL: CT, PET, and fusion images; R-signature score 0.023 (low risk); HE staining shows predominantly centrocytes within the tumor follicles with slightly irregular nuclei. B II Grade FL: CT, PET, and fusion images; R-signature score 0.081 (low risk); HE staining shows tumor follicles containing both centrocytes and centroblasts, with a predominance of centrocytes. C IIIa Grade FL: CT, PET, and fusion images; R-signature score 0.138 (low risk); HE staining shows numerous centroblasts scattered among centrocytes. D t-FL: CT, PET, and fusion images; R-signature score 0.806 (high risk); HE staining shows sheets of aggregated centroblasts