Carlos A. Cabal Mirabal’s research while affiliated with University of Havana and other places

Knowledge of the longitudinal and transverse relaxivities (r1 and r2) of a contrast agent (CA) is essential for its magnetic characterization. These parameters can be measured using Magnetic Resonance Imaging (MRI) clinical scanners with the advantage of characterizing the CA under the same experimental conditions where it will be employed. Nevertheless, when using MRI, there are several limitations to consider, and we provide ways to compensate for them to obtain accurate results. We present a fast and robust methodology to determine the relaxivity of CA solutions using a 3 T MRI clinical scanner with a single-channel transmit-receive birdcage coil. We performed relaxivity measurements on a phantom consisting of five samples of copper sulfate at different concentrations. We optimized image acquisition for total scan time using three different pulse sequences. Post-processing steps following image acquisition were implemented in a semiautomatic MATLAB toolbox. Relaxation times were estimated using the three-parameter model with the Levenberg-Marquardt algorithm. Statistical comparisons demonstrate good reproducibility and robustness in the relaxivity estimation by each method. This paper presented a methodology and a systematic discussion of experimental factors associated with relaxivity determination.