Growth of Magnetic Resonance Imaging (MRI) distinction brokers (CAs) continues to be one of many analysis hotspots as a result of inherent limitations of T1- or T2- weighted CAs, and T1/T2 dual-mode CAs. To dramatically improve the MRI distinction between tumors and regular tissues, we suggest a brand new idea of opposite contrast-MRI (CC-MRI), whose particular definition is that CC-MRI CAs current constructive or destructive alerts at regular tissues, however present opposite alerts at diseased tissues. To comprehend CC-MRI of tumors, we designed and developed a tumor microenvironment (TME) twin responsive CA (i.e., SA-FeGdNP-DOX@mPEG), which is sort of not aware of regular physiological situations, however extremely aware of acidic and reductive TME. Our SA-FeGdNP-DOX@mPEG reveals destructive MRI sign beneath regular physiological situations as a result of excessive r2 worth (336.9 mM-1 s-1) and excessive r2/r1 ratio (18.4), however switches to constructive MRI sign at TME due to the excessive r1 worth (20.32 mM-1 s-1) and low r2/r1 ratio (7.2). Our TME twin responsive SA-FeGdNP-DOX@mPEG considerably enhanced the distinction of MR photos between tumors and livers, and the ΔSNR distinction reached 501%. As well as, our SA-FeGdNP-DOX2@mPEG2 with tumor targetability and managed DOX launch responding to TME had been additionally used for tumor-specific chemotherapy with decreased negative effects.