Estimation of mean pulmonary artery pressure by cardiovascular magnetic resonance 4D Flow and compressed sensing

4D phase-contrast cardiovascular magnetic resonance (CMR) allows for 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 2D (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, comparing both to right heart catheterization (RHC).

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. CS-M2D and CS-4D both had average scan durations under 3 min (175 ± 36 and 135 ± 34 s, respectively). Estimated mPAP by CS-4D and CS-M2D were strongly correlated (R ² = 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 (R ² = 0.92, P < 0.001, bias 0.6 ± 3.1 mmHg) and CS-4D (R ² = 0.86, P < 0.001, bias 1.1 ± 4.5 mmHg).

CS-4D and CS-M2D sequences yield interchangeable estimations of mPAP, with excellent agreement to invasive RHC. Both be acquired in a scan time applicable to clinical workflow, offering promising tools for non-invasive mPAP estimation in clinical practice.