Estimation of mean pulmonary artery pressure by cardiovascular magnetic resonance four-dimensional flow and compressed sensing

Background Four-dimensional (4D) phase-contrast cardiovascular magnetic resonance (CMR) allows for precise non-invasive estimation of mean pulmonary artery pressure (mPAP) by estimating the duration of pathological vortex persistence in the main pulmonary artery. This has previously been achieved with compressed sensing acceleration of a multiple two-dimensional (CS-M2D) flow sequence, but acquisition using a true time-resolved 3D excitation (CS-4D) offers theoretical advantages including spatiotemporal coherence. This study aimed to validate a state-of-the-art CS-4D sequence with a previously utilized CS-M2D sequence for estimating mPAP, and compare both to right heart catheterization (RHC). Methods The study included patients clinically referred for CMR (n=45), of which a subgroup (n=20) had prior mPAP of >16 mmHg confirmed by RHC. CMR was performed at 1.5T using CS-M2D and CS-4D sequences covering the main pulmonary artery. mPAP was estimated using a previously published linear relationship between vortex duration and mPAP. Agreement between CS-M2D and CS-4D estimates was quantified, including analysis of intra- and interobserver variabilities. The diagnostic performance of CS-M2D and CS-4D in predicting mPAP was further compared to gold-standard RHC. Results CS-M2D and CS-4D both had average scan durations under 3 minutes (175±36 and 135±34 seconds, respectively). Estimated mPAP by CS-4D and CS-M2D were strongly correlated (R2=0.93, p<0.001), with negligible mean±SD bias (0.0±2.7 mmHg) and good reproducibility. There was excellent agreement with RHC for both CS-M2D (R2=0.92, p<0.001, bias 0.6±3.1 mmHg) and CS-4D (R2=0.86, p<0.001, bias 1.1±4.5 mmHg). Conclusions CS-4D and CS-M2D sequences effectively yield interchangeable non-invasive estimations of mPAP, with excellent agreement compared to invasive RHC. They can both be acquired in a scan time applicable to clinical workflow, offering a promising tool for non-invasive mPAP estimation in clinical practice. ### Competing Interest Statement D.G., N.J. and F.T. are employees of Siemens Healthineers. G.A., P.B., J.C., A.F., P.S., A.S., M.U., and D.M. are all either employed by or affiliated with Karolinska University Hospital, which has an institutional research and development agreement regarding cardiovascular magnetic resonance with Siemens Healthineers. ### Funding Statement This work was funded in part by the European Union (ERC, MultiPRESS, 101075494). Views and opinions expressed are those of the authors and do not reflect those of the European Union or the European Research Council Executive Agency. Funding was also provided in part by New South Wales Health, Heart Research Australia, University of Sydney. ### 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: All subjects provided written informed consent, and the study was approved by the Swedish Ethical Review Authority (DNR: 2015/2106-31/1). 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 The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. * 4D : Four-dimensional CMR : cardiovascular magnetic resonance mPAP : mean pulmonary artery pressure CS : compressed sensing CS-M2D : compressed sensing multiple two-dimensional (flow sequence) CS-4D : compressed sensing time-resolved three-dimensional (flow sequence) RHC : right heart catheterization bSSFP : balanced steady-state free precession MPA : main pulmonary artery RV : right ventricle TAPSE : tricuspid annular plane excursion