Among the four postprocessing metrics applied to APTw-CEST, AREX and MTRREX (Fig. 5c, d) significantly differentiated Luminal A from HER2+ (*p = 0.021; *p = 0.027) and Luminal A from triple-negative (**p = 0.006; **p = 0.003), demonstrating rising APTw-CEST signals with increasing BC subtype aggressiveness. Here, ERBB2 is linked to breast cancer.