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Simultaneous imaging and R2* mapping using a radial multi-gradient-echo (rMGE) sequence.

Stefanie Winkelmann·Tobias Schaeffter·Steffen Weiss·Holger Eggers·Olaf Doessel
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Abstract

PURPOSE: To demonstrate a rapid MR technique that combines imaging and R2* mapping based on a single radial multi-gradient-echo (rMGE) data set. The technique provides a fast method for online monitoring of the administration of (super-)paramagnetic contrast agents as well as image-guided drug delivery. MATERIALS AND METHODS: Data are acquired using an rMGE sequence, resulting in interleaved undersampled radial k-spaces representing different echo times (TEs). These data sets are reconstructed separately, yielding a series of images with different TEs used for pixelwise R2* mapping. A fast numerical algorithm implemented on a real-time reconstruction platform provides online estimation of the relaxation rate R2*. Simultaneously the images are summed for the computation of a high-resolution image. RESULTS: Convenient high-resolution R2* maps of phantoms and the liver of a healthy volunteer were obtained. In addition to stable intrinsic baseline maps, the proposed technique provides particularly accurate results for the high relaxation rates observed during the presence of (super-)paramagnetic contrast agents. Assuming that the change in R2* is proportional to the concentration of the agent, the technique offers a rough estimate for dynamic dosage. CONCLUSION: The simultaneous online display of morphological and parametric information permits convenient, quantitative surveillance of contrast-agent administration.

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AlgorithmsContrast MediaDextransFerrosoferric OxideHumansImage Processing, Computer-AssistedIronLiverMagnetic Resonance ImagingMagnetite NanoparticlesOxidesPhantoms, ImagingJournal Article

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Stefanie Winkelmann, Tobias Schaeffter, Steffen Weiss, Holger Eggers, Olaf Doessel. 2006. Simultaneous imaging and R2* mapping using a radial multi-gradient-echo (rMGE) sequence.. https://doi.org/10.1002/jmri.20712

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