Main textIn 2017, comparisons of activity measurements of 18F, 64Cu, 99mTc and 11C using the Transfer Instrument of the International Reference System (SIRTI) took place at the National Research Council of Canada (NRC, Canada). Ampoules containing 18F, 64Cu, 99mTc and 11C solutions were measured in the SIRTI for about three half-lives (10 half-lives for 11C). The NRC standardized the activity in the ampoules by 4π(PC)β−γ anti-coincidence measurements (CIEMAT/NIST liquid scintillation counting for 11C). The comparisons, identifiers BIPM.RI(II)-K4.F-18, BIPM.RI(II)-K4.Cu-64 and BIPM.RI(II)-K4.Tc-99m are linked to the corresponding BIPM.RI(II)-K1.F-18, BIPM.RI(II)-K1.Cu-64 and BIPM.RI(II)-K1.Tc-99m comparisons. The BIPM.RI(II)-K1 18F and 99mTc key comparison reference values have been updated to include the latest BIPM.RI(II)-K4 linked results and degrees of equivalence for those three comparisons have been evaluated.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).