Improving 3D-CINE tTV-regularized whole-heart MRI reconstruction

Purpose: To improve the image quality of 3D radial free-running MRI data of the heart through a deliberate and stepwise extension of the XD-GRASP reconstruction. Methods: Ferumoxytol-enhanced cardiac free-running 3D-radial data were reconstructed using an XD-GRASP reconstruction improved by 4 new developments: motion-compensated temporal-Total-Variation (MC–tTV) regularization for 3D images, a new coil-sensitivity, a new k-space density compensation and a revisited conjugate-gradient-descent (with exact line search) for solving the least-square sub-problem of ADMM. The resulting images were compared quantitatively and qualitatively to reconstructions lacking some of the newly implemented measures. Also, the measurement of ejection-fraction by a threshold–based method on the new reconstruction was compared to a reference standard. Results: The new reconstruction significantly increased the sharpness of the right coronary artery (4% to 6%, p < 0.05) and the left anterior descending coronary artery (4% to 5% p < 0.05). It also increased blood–myocardium interface sharpness (between 20% and 25%, p < 0.05) and decreases spatial-Total-Variation in the blood-pool (13%, p < 0.05). The qualitative evaluation suggests better anatomical depiction of small structures using the new reconstruction. As compared to a reference standard method, ejection fraction could also be correctly evaluated. Conclusion: Compressed sensing image reconstruction for 3D-radial free-running cardiac acquisition was successfully improved by including MC–tTV regularization, a new density compensation, a new coil-sensitivity and a revisited conjugate-gradient-descent with exact line search. Quantitative and qualitative quality metrics demonstrated significant improvement in image quality when using the new reconstruction, while extracted dynamic information compared favorably with the gold standard. Keywords: Cardiac, 3D, CINE, radial, free-running, deformation-fields. ### Competing Interest Statement The PhD studies of Ludovica Romanin are supported financially by Siemens Healthcare, Erlangen, Germany. Juerg Schwitter receives unrestricted grant support from Bayer Healthcare, Schweiz, AG. Matthias Stuber receives non-monetary research support from Siemens Healthineers. ### Funding Statement This study was funded by the Swiss National Science Foundation (grant number 320030B_201292). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The ethics committee of the canton de Vaud, Switzerland, gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors.