*2.1. Database Description*

The whole slide images (WSIs) of kidney biopsy specimens of 65 patients (median age 51 years, range 29–74 years) were used for this work; these were collected at the Division of Pathology, AOU Città della Salute e della Scienza Hospital, Turin, Italy and then anonymized. The pathology laboratory managed the biopsied samples of each kidney according to the kidney transplant biopsy's internal protocol. The tissue was fixed with Serra fixative and then processed in an urgency regimen using a microwave processor or LOGOS J processor (Milestone, Bergamo, Italy). Samples were then para ffin-embedded and serially sectioned (5 μm), mounted onto adhesive slides, and stained with PAS and TRIC. Finally, all the slides produced were scanned with a Hamamatsu NanoZoomer S210 Digital slide scanner (Turin, Italy), providing a magnification of ×100 (conversion factor: 0.934 μm/pixel). For each patient (*n* = 65), an expert pathologist (A.B.) manually extracted 10 images with dimensions of 512 × 512 pixels, for a total of 650 images. After consensus, manual annotations of blood vessels and fibrosis were generated by two operators (A.G. and L.M.). Table 1 shows the overall dataset composition. The image dataset, along with the annotations, is available at https://data.mendeley.com/ datasets/m2t49zf6xr/1.

**Table 1.** Dataset used in this work.

