Illustration of coronal fused PET/CT images with [18F]fludarabine and [18F]FDG and quantitative comparative analysis. (a) Maximum intensity projections (3D rendering) highlighting the difference between these two radiotracers in terms of normal physiological uptake (e.g. brain, heart, etc.); the totality of the tumour is delineated on the illustrations. (b) Relationship between quantitative values extracted from PET/CT and histology; PET quantification with VOITOT taking into account the tumour heterogeneity. Total uptake [%ID/ml] of the tracer was correlated to the percentage of lymphoid cells in representative sections from each lymphoma as determined by automatic quantification of the histological slices ([18F]fludarabine, n = 7: left graph and [18F]FDG, n = 8: right graph). Correlation coefficients and significance were determined using Pearson’s test.