Abstract
PurposeThree-dimensional (3D) magnetic resonance phase contrast imaging (PC-MRI) allows non-invasive diagnosis of pulmonary hypertension (PH) and estimation of elevated mean pulmonary arterial pressure (mPAP) based on vortical motion of blood in the main pulmonary artery. The purpose of the present study was to compare the presence and duration of PH-associated vortices derived from different flow visualization techniques with special respect to their performance for non-invasive assessment of elevated mPAP and diagnosis of PH.MethodsFifty patients with suspected PH (23 patients with and 27 without PH) were investigated by right heart catheterization and time-resolved PC-MRI of the main pulmonary artery. PC-MRI data were visualized with dedicated prototype software, providing 3D vector, multi-planar reformatted (MPR) 2D vector, streamline, and particle trace representation of flow patterns. Persistence of PH-associated vortical blood flow (tvortex) was evaluated with all visualization techniques. Dependencies of tvortex on visualization techniques were analyzed by means of correlation and receiver operating characteristic (ROC) curve analysis.Resultstvortex values from 3D vector visualization correlated strongly with those from other visualization techniques (r = 0.98, 0.98 and 0.97 for MPR, streamline and particle trace visualization, respectively). Areas under ROC curves for diagnosis of PH based on tvortex did not differ significantly and were 0.998 for 3D vector, MPR vector and particle trace visualization and 0.999 for streamline visualization. Correlations between elevated mPAP and tvortex in patients with PH were r = 0.96, 0.93, 0.95 and 0.92 for 3D vector, MPR vector, streamline and particle trace visualization, respectively. Corresponding standard deviations from the linear regression lines ranged between 3 and 4 mmHg.Conclusion3D vector, MPR vector, streamline as well as particle trace visualization of time-resolved 3D PC-MRI data of the main pulmonary artery can be employed for accurate vortex-based diagnosis of PH and estimation of elevated mPAP.
Highlights
Pulmonary hypertension (PH) is a life-threatening complex pathophysiological condition characterized by mean pulmonary arterial pressure equal to or exceeding 25 mmHg at rest [1,2]
The purpose of the present study was to compare the presence and duration of PH-associated vortical motion of blood in the main pulmonary artery on multi-planar reformatted (MPR) vector, streamline, and particle trace visualization with results obtained from 3D vector visualization with special respect to their performance for non-invasive assessment of elevated mean pulmonary arterial pressure (mPAP) and diagnosis of PH
Comparison of Flow Visualization Techniques tvortex determined by MPR vector, streamline and particle trace visualization correlated strongly with tvortex derived from 3D vector representation (r = 0.98, 0.98 and 0.97, respectively). tvortex determined from MPR vectors, streamlines and particle traces were, slightly larger than tvortex determined from 3D vectors, with a standard deviation of measurement differences of 5–6% of the RR-interval (Figure 2)
Summary
Pulmonary hypertension (PH) is a life-threatening complex pathophysiological condition characterized by mean pulmonary arterial pressure (mPAP) equal to or exceeding 25 mmHg at rest [1,2]. It is associated with vortical motion of blood in the main pulmonary artery [3], which can be evaluated from time-resolved 3-dimensional (3D) phase contrast magnetic resonance imaging (PC-MRI). Visualization of 3D velocity fields is crucial for detecting flow patterns in general and vortices in particular, but it remains challenging. Post-processing techniques commonly applied to visualize 3D PC-MRI data represent velocities as 3D vectors or multi-planar reformatted (MPR) 2-dimensional (2D)
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