The present invention provides a method of MR investigation of a sample, said method comprising: (i) nuclear spin polarizing a high T1 MR imaging agent which contains in its molecular structure at least two hyperpolarisable nuclei within the same molecule, the frequency difference between the two resonance lines from said nuclei, .delta..upsilon., being dependent upon either the temperature or the pH of said sample; (ii) administering the nuclear spin polarized MR imaging agent to said sample; (iii) exposing said sample to a radiation at a frequency selected to excite nuclear spin transitions in said MR imaging agent; and (iv) detecting and manipulating magnetic resonance signals from said sample using a single-shot RARE acquisition sequence with shifted data acquisition.