Improved Myocardial Sodium Quantification at 7 T Using Interleaved 23 Na / 1 H pTx MRI With Motion and Anatomy‐Based B 1 Correction

Magnetic Resonance in Medicine, vol. 96, pp. 173–190

Abstract

ABSTRACT Purpose To improve accuracy and repeatability of myocardial 23 Na quantification in cardiac MRI at 7 T by combining retrospective respiratory and cardiac motion correction with a novel anatomy‐based B 1 bias field correction. Methods In this study, a dual‐nuclear interleaved 23 Na/ 1 H MRI sequence at 7 T was applied. Here, 1 H MR data enabled automated segmentation of myocardium and blood pool via nnUNet and facilitated respiratory and cardiac motion correction for both contrasts using 1 H navigators. For 23 Na MRI, a novel anatomy‐based B 1 bias field correction was developed, estimating the transmit and receive (B 1 ) field bias from 1 H‐derived segmentations and synthetic 23 Na images. All correction methods were validated through realistic simulations and in vivo studies. Repeatability was assessed in 10 healthy subjects, and the proposed B 1 correction was compared to phantom‐based methods. Results Respiratory and cardiac motion correction reduced quantification errors and improved SNR compared to conventional gating. The anatomy‐based B 1 correction effectively mitigated errors caused by B 1 inhomogeneities and outperformed phantom‐based methods in terms of repeatability. The measured apparent tissue sodium concentration of the myocardium after all corrections (49.5 4.7 mM) was consistent with literature values. Combined motion and B 1 corrections improved repeatability, reducing the coefficient of repeatability from 4.9 mM (11.2%) without corrections to 2.0 mM (4.0%) after corrections. Conclusion The combination of retrospective motion correction and anatomy‐based B 1 bias field correction enables repeatable myocardial sodium quantification at 7 T. The interleaved acquisition facilitates robust segmentation and efficient use of 1 H MRI for motion and B 1 correction, providing a scalable framework for future clinical research studies.

Authors 10

1. Laurent Ruck

   Friedrich-Alexander-Universität Erlangen-Nürnberg · Universitätsklinikum Erlangen

   Affiliation as printed

   Institute of Radiology, University Hospital Erlangen, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU) Erlangen Germany

2. Nico Egger

   Friedrich-Alexander-Universität Erlangen-Nürnberg · Universitätsklinikum Erlangen

   Affiliation as printed

   Institute of Radiology, University Hospital Erlangen, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU) Erlangen Germany

3. Benedikt Zobler

   Friedrich-Alexander-Universität Erlangen-Nürnberg

   Affiliation as printed

   Department of Nephrology and Hypertension Friedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU) Erlangen Germany

4. Judith Schirmer

   Friedrich-Alexander-Universität Erlangen-Nürnberg · Universitätsklinikum Erlangen

   Affiliation as printed

   Institute of Radiology, University Hospital Erlangen, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU) Erlangen Germany

5. Sophia Nagelstraßer

   Friedrich-Alexander-Universität Erlangen-Nürnberg · Universitätsklinikum Erlangen

   Affiliation as printed

   Institute of Radiology, University Hospital Erlangen, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU) Erlangen Germany

6. Andreas K. Bitz Aachen

   FH Aachen

   Affiliation as printed

   Electrical Engineering and Information Technology University of Applied Sciences – FH Aachen Aachen Germany

7. Tanja Platt

   German Cancer Research Center

   Affiliation as printed

   Medical Physics in Radiology German Cancer Research Center (DKFZ) Heidelberg Heidelberg Germany

8. Simon Konstandin

   Fraunhofer Institute for Digital Medicine

   Affiliation as printed

   Fraunhofer Institute for Digital Medicine MEVIS Bremen Germany

9. Michael Uder

   Friedrich-Alexander-Universität Erlangen-Nürnberg · Universitätsklinikum Erlangen

   Affiliation as printed

   Institute of Radiology, University Hospital Erlangen, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU) Erlangen Germany

10. Armin Michael Nagel

    German Cancer Research Center · Friedrich-Alexander-Universität Erlangen-Nürnberg · Universitätsklinikum Erlangen

    Affiliation as printed

    Institute of Radiology, University Hospital Erlangen, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU) Erlangen Germany

    Medical Physics in Radiology German Cancer Research Center (DKFZ) Heidelberg Heidelberg Germany