Performance of standard toxicity assays compared with RF-derived most predictive genes and imaging features. (A) Receiver operating characteristic curve (ROC) for (1) standard toxicity assays (cell viability: Celltiter Glo ATP assay; cell death: number of dead cells based on TOTO-3 iodine dye), (2) predictive genes, identified by RF feature reduction (HMOX1 and SQSTM1), and (3) imaging features identified by RF feature reduction (Cell Radial Deviation SER-Dark, Texture Nucleus SER-Saddle, Nucleus Profile 4/5 SER-Saddle). Data represent maximal upregulation of 38 kidney toxic compounds and 8 nontoxic controls across all concentrations at 24 h. Area under the ROC curve (AUROC) was calculated using GraphPad Prism software. Cut-off was calculated using the maximum YI (Youden Index = Sensitivity +Specificity − 1). (B) ROC-derived cut-offs were used as a threshold to calculate number of False Positive (FP), True Positive (TP), False Negative (FN), and True Negative (TN) compounds. Sensitivity or True Positive Rates (TPR) were calculated as #True Positive/All Positive. Specificity or True Negative Rates (TNR) were calculated as #True Negative/All Negative. Accuracy was calculated as (TP + TN)/(TP + FP + FN + TN).