The main drawback of the described SO relaxation experiment is the low level of SO signal enhancement provided by SABRE at near zero field (protocol 2). Therefore, we conducted experiments comprising SABRE enhancement of the net 15 N magnetization at 400 nT field with its subsequent conversion into SO at high field by using M2S pulse sequence (protocol 3). Such experiment indicates the same SO lifetime, as in the experiments with direct SO polarization, yet provides the higher level of the resulting signal. Thus, such experimental approach allows yields 0.33 % of N polarization for zero relaxation delay at high field, in contrast to 0.17 % observed with direct SO polarization. These values are four times lower than the polarized net magnetization of N nuclei (1.2 %), however, after 50 s at 9.4 T net magnetization decays almost to zero, while SO derived signal does not change at all. At 0.1 T the magnetization persists longer, but SO outruns it in intensity after 8 minutes and is clearly observed even after 17 minutes (Fig. ). It is also noteworthy, that the long lived SO of trans-15 N2-ABZ is in fact delocalized among N nuclei and ortho protons of ABZ, which allows to detect SO be means of 1 H NMR. 11 This is of great interest for MRI applications, as such experiments do not require equipment for heteronuclear detection, which is not common in typical MRI scanners.