## Fast myocardial T$$_{1P}$$ mapping in mice using k-space weighted image contrast and a Bloch simulation-optimized radial sampling pattern

Please always quote using this URN: urn:nbn:de:bvb:20-opus-268903
• Purpose T$$_{1P}$$ dispersion quantification can potentially be used as a cardiac magnetic resonance index for sensitive detection of myocardial fibrosis without the need of contrast agents. However, dispersion quantification is still a major challenge, because T$$_{1P}$$ mapping for different spin lock amplitudes is a very time consuming process. This study aims to develop a fast and accurate T$$_{1P}$$ mapping sequence, which paves the way to cardiac T1ρ dispersion quantification within the limited measurement time of an in vivo study inPurpose T$$_{1P}$$ dispersion quantification can potentially be used as a cardiac magnetic resonance index for sensitive detection of myocardial fibrosis without the need of contrast agents. However, dispersion quantification is still a major challenge, because T$$_{1P}$$ mapping for different spin lock amplitudes is a very time consuming process. This study aims to develop a fast and accurate T$$_{1P}$$ mapping sequence, which paves the way to cardiac T1ρ dispersion quantification within the limited measurement time of an in vivo study in small animals. Methods A radial spin lock sequence was developed using a Bloch simulation-optimized sampling pattern and a view-sharing method for image reconstruction. For validation, phantom measurements with a conventional sampling pattern and a gold standard sequence were compared to examine T$$_{1P}$$ quantification accuracy. The in vivo validation of T$$_{1P}$$ mapping was performed in N = 10 mice and in a reproduction study in a single animal, in which ten maps were acquired in direct succession. Finally, the feasibility of myocardial dispersion quantification was tested in one animal. Results The Bloch simulation-based sampling shows considerably higher image quality as well as improved T$$_{1P}$$ quantification accuracy (+ 56%) and precision (+ 49%) compared to conventional sampling. Compared to the gold standard sequence, a mean deviation of - 0.46 ± 1.84% was observed. The in vivo measurements proved high reproducibility of myocardial T$$_{1P}$$ mapping. The mean T$$_{1P}$$ in the left ventricle was 39.5 ± 1.2 ms for different animals and the maximum deviation was 2.1% in the successive measurements. The myocardial T$$_{1P}$$ dispersion slope, which was measured for the first time in one animal, could be determined to be 4.76 ± 0.23 ms/kHz. Conclusion This new and fast T$$_{1P}$$ quantification technique enables high-resolution myocardial T$$_{1P}$$ mapping and even dispersion quantification within the limited time of an in vivo study and could, therefore, be a reliable tool for improved tissue characterization.

Author: Maximilian Gram, Daniel Gensler, Patrick Winter, Michael Seethaler, Paula Anahi Arias-Loza, Johannes Oberberger, Peter Michael Jakob, Peter Nordbeck urn:nbn:de:bvb:20-opus-268903 Journal article Fakultät für Physik und Astronomie / Physikalisches Institut Medizinische Fakultät / Klinik und Poliklinik für Nuklearmedizin Medizinische Fakultät / Medizinische Klinik und Poliklinik I Medizinische Fakultät / Deutsches Zentrum für Herzinsuffizienz (DZHI) English Magnetic Resonance Materials in Physics, Biology and Medicine 1352-8661 2022 35 2 325–340 Magnetic Resonance Materials in Physics, Biology and Medicine 2022, 35(2):325–340. DOI: 10.1007/s10334-021-00951-y https://doi.org/10.1007/s10334-021-00951-y https://pubmed.ncbi.nlm.nih.gov/34491466 6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit KWIC; TT$$_{1rho}$$ mapping; T$$_{1P}$$ dispersion; T$$_{1P}$$ mapping; cardiac; mice; radial; small animal; spin lock 2022/06/09 CC BY: Creative-Commons-Lizenz: Namensnennung 4.0 International