Comparison of 4D Flow MRI to 2D Flow MRI in the pulmonary arteries in healthy volunteers and patients with pulmonary hypertension

Abstract

Purpose4D and 2D phase-contrast MRI (2D Flow MRI, 4D Flow MRI, respectively) are increasingly being used to noninvasively assess pulmonary hypertension (PH). The goals of this study were i) to evaluate whether established quantitative parameters in 2D Flow MRI associated with pulmonary hypertension can be assessed using 4D Flow MRI; ii) to compare results from 4D Flow MRI on a digital broadband 3T MR system with data from clinically established MRI-techniques as well as conservation of mass analysis and phantom correction and iii) to elaborate on the added value of secondary flow patterns in detecting PH.Methods11 patients with PH (4f, 63 ± 16y), 15 age-matched healthy volunteers (9f, 56 ± 11y), and 20 young healthy volunteers (13f, 23 ± 2y) were scanned on a 3T MR scanner (Philips Ingenia). Subjects were examined with a 4D Flow, a 2D Flow and a bSSFP sequence. For extrinsic comparison, quantitative parameters measured with 4D Flow MRI were compared to i) a static phantom, ii) 2D Flow acquisitions and iii) stroke volume derived from a bSSFP sequence. For intrinsic comparison conservation of mass-analysis was employed. Dedicated software was used to extract various flow, velocity, and anatomical parameters. Visualization of blood flow was performed to detect secondary flow patterns.ResultsOverall, there was good agreement between all techniques, 4D Flow results revealed a considerable spread. Data improved after phantom correction. Both 4D and 2D Flow MRI revealed concordant results to differentiate patients from healthy individuals, especially based on values derived from anatomical parameters. The visualization of a vortex, indicating the presence of PH was achieved in 9 /11 patients and 2/35 volunteers.DiscussionThis study confirms that quantitative parameters used for characterizing pulmonary hypertension can be gathered using 4D Flow MRI within clinically reasonable limits of agreement. Despite its unfavorable spatial and lesser temporal resolution and a non-neglible spread of results, the identification of diseased study participants was possible.

Cardiac Magnetic Resonance in Pulmonary Hypertension—an Update

“…In the setting of PH, 4D flow has been used to assess the haemodynamic changes in the pulmonary circulation. Abnormal flow patterns in the main pulmonary artery (MPA), namely vortex formation, have been associated with PH [76,77]. The presence and 'persistence time' of the vortex in the MPA are linearly associated with mPAP [78,79] and can be used to estimate mPAP.…”

MR 4D flow-based mean pulmonary arterial pressure tracking in pulmonary hypertension

“…Even though the role of cardiac MRI in the clinical management of PH is not yet established, the method offers various tools particularly suitable for PH treatment monitoring and patient follow-up. Allowing for an accurate evaluation of cardiac function and morphology, various quantitative MRI parameters have been reported to be significantly altered in PH [7][8][9][10][11][12][13][14][15][16][17][18][19][20] including, among others, the appearance of vortical blood flow along the main pulmonary artery as assessed by time-resolved, three-directional MR phase contrast (4D flow) imaging [19,[21][22][23][24][25][26][27][28]. Moreover, the duration of vortical blood flow was introduced as a potential 4D flow metric for accurate non-invasive estimation of elevated mPAP [26,27], making MR 4D flow imaging particularly interesting for noninvasive mPAP tracking.…”

4D flow CMR analysis comparing patients with anatomically shaped aortic sinus prostheses, tube prostheses and healthy subjects introducing the wall shear stress gradient: a case control study

“…Moreover, the SP allows for formation of vortices in the sinus [ 15 ]. Vortices, in general, have been discussed to preserve kinetic energy [ 17 , 18 ] which may then be released later in the cardiac cycle, partly mimicking a Windkessel effect. Whether the increased maximum area of the aorta in patients is linked to post-prosthetic dilatation or the individual’s pre-existing vessel dilation remains hypothetical.…”

“…While secondary flow patterns are often used as markers for the presence of pathological hemodynamics or even for a specific pathology, e.g. pulmonary artery hypertension [17,18], the effect of these secondary flow patterns on pathological changes of the vessel wall architecture and thus the long-term morbidity of patients exhibiting these flow patterns remain a subject of debate.…”