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Objective: 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 1m ) and limit of detection (LOD)., Materials and Methods: 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 1 of DO was estimated from the measured DO concentrations and T 1 relaxation rates (R 1 ). The results were combined with previously reported values on in vivo stability measures of the MOLLI sequences and used to estimate a LOD., Results: DO concentrations ranged from 0.5 to 21.6 mg L -1 . A linear correlation between DO and R 1 was obtained with both MOLLI sequences, with an average correlation coefficient (R 2 ) 0.9 and an average estimated r 1 ([Formula: see text]) of 4.45 × 10 -3  s -1  mg -1  L. Estimated LOD was ≈ 10 mg L -1 ., Conclusion: MOLLI T 1 -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 -3  s -1  mg -1  L and a corresponding LOD for dissolved oxygen of approximately 10 mg L -1 . MOLLI-based T 1 mapping may be a useful non-invasive tool for quantification of in vivo changes of DO concentration during oxygen challenges.

Purpose: To test the feasibility of a novel "split dynamic" method in which high temporal and high spatial resolution dynamic MR images are acquired during a single bolus injection., Materials and Methods: High temporal resolution images were acquired using a three-dimensional (3D) dual-echo EPI sequence. The high spatial resolution images were acquired using a 3D T1 -weighted turbo field echo sequence. Simulations were performed to test the split dynamic method in terms of accuracy relative to a continuous acquisition and for temporal sampling requirements for accurate estimation of kinetic parameters. The method was tested in four patients where pharmacokinetic parameters were extracted from the high temporal resolution data., Results: The split dynamic method enabled quantitative evaluation of both T1- and T2*-weighted characteristics. Simulations showed that splitting the dynamic acquisition does not significantly influence the reliability of parameter estimations. Simulation showed a required temporal resolution of 13, 16, and 8 s for accurate estimates of Ktrans, ve, and vp, respectively, and an optimal sampling interval between 2 and 6 s for peak R2*., Conclusion: The split dynamic sequence enabled detailed assessment of dynamic T1- and T2*-weighted contrast kinetics without compromising guidelines concerning spatial resolution., (Copyright © 2013 Wiley Periodicals, Inc.)