“…A clinical validation of the radiomics-based prediction model was reported in 19 (39%) of the 49 papers. It was performed on a separate set of data from the primary institution, i.e., internal test set, in 14 (29%) studies [ 15 , 16 , 22 , 24 , 28 , 31 , 32 , 35 , 37 , 38 , 41 , 46 , 47 , 52 ]. It was performed on an independent set of data from the primary institution (related to a different scanner) or from an external institution, i.e., external test set, in 5 (10%) studies [ 25 , 27 , 29 , 43 , 51 ].…”