Metabolic imaging is commonly performed by nuclear medicine facilities such as PET or SPECT, etc. The production and biomedical applications of bio-molecular sensing in vivo MRI metabolic contrast agents has recently become of great universal research interest, which follows its great success as a potential cost effective, less radioactive, nuclear medicine alternative. Temperature, redox potential, enzyme activity, free radial/metal ion responsive and/or pH sensitive molecular metabolic MR contrast agents are among the famous instances exemplified, which basically promote MR image contrast enhancement ability to distinguish molecular metabolic/gene expression features. Overall, these MRI contrast agents provide a framework to achieve a greater degree of accuracy from MRI as a low cost, more available facility, non radioactive radiation producing and highly sensitive biomedical tool to propound as a new suggesting opponent for PET nuclear medicine imaging. In the present review, the design, development, examination and future of the above agents will be discussed in detail.