To investigate the sensitivity of modified Look-Locker inversion recovery (MOLLI) to measure changes in dissolved oxygen (DO) concentrations in water samples and to calculate sequence-specific relaxivity (r) and limit of detection (LOD).Ten water samples with a range of DO concentrations were scanned at 3 T using two variations of MOLLI schemes. Using linear regression the r of DO was estimated from the measured DO concentrations and T relaxation rates (R). The results were combined with previously reported values on in vivo stability measures of the MOLLI sequences and used to estimate a LOD.DO concentrations ranged from 0.5 to 21.6 mg L. A linear correlation between DO and R was obtained with both MOLLI sequences, with an average correlation coefficient (R) 0.9 and an average estimated r ([Formula: see text]) of 4.45 × 10 s mg L. Estimated LOD was ≈ 10 mg L.MOLLI T-mapping sequences may be used for detecting dissolved oxygen in vivo at 3 T with an [Formula: see text] in the range 4.18-4.8 × 10 s mg L and a corresponding LOD for dissolved oxygen of approximately 10 mg L. MOLLI-based T mapping may be a useful non-invasive tool for quantification of in vivo changes of DO concentration during oxygen challenges.