Clinical Application of 4D Flow MR Imaging to Pulmonary Hypertension

Abstract

Pulmonary hypertension (PH) is characterized by elevated pulmonary arterial pressure (PAP). Although rightheart catheterization is the gold standard method for the diagnosis of PH by definition, various less-invasive imaging tests have been used for screening, detection of underlying diseases-causing PH, and monitoring of diseases. Among them, 4D flow MRI is an emerging and unique imaging test that allows for comprehensive visualization of blood flow in the right heart and proximal pulmonary arteries. The characteristic blood flow pattern observed in patients with PH is vortical flow formation in the main pulmonary artery. Recent studies have proposed the use of these findings to determine not only the presence of PH but also estimate the mean PAP. Other applications of 4D flow MRI for PH include measurement of wall shear stress, helicity, and 3D flow balance in the pulmonary arteries. It is worth noting that 4D flow has also the potential for longitudinal followups. In this review, the clinical definition of PH, summary of conventional imaging tests, characteristics of pulmonary arterial flow as shown by 4D flow MRI, and clinical application of 4D flow MRI in the management of patients with PH will be discussed.

Validation of cardiac index measured by four‐dimensional cardiac magnetic resonance flow against the invasively measured cardiac index in patients with pulmonary hypertension

“…In patients with PH, the secondary morphological change in the form of the dilation of the pulmonary arterial trunk leads to disturbing the pulmonary blood flow and formation of vortex flow. Previous literature documented that this change in the geometry of the pulmonary arterial trunk in patients with PH affects the shape of vortices in pulmonary flow 38–42 . All patients showed vortices in the pulmonary artery trunk and eccentric helical right‐sided flow in our study.…”

“…Previous literature documented that this change in the geometry of the pulmonary arterial trunk in patients with PH affects the shape of vortices in pulmonary flow. [38][39][40][41][42] All patients showed vortices in the pulmonary artery trunk and eccentric helical right-sided flow in our study. Addressing the previously mentioned limitation of 2D flow, the change in the PA geometry makes it challenging for 2D flow CMR to be accurate in the flow analysis.…”

Pulmonary Arterial Hypertension: Emerging Principles of Precision Medicine across Basic Science to Clinical Practice

“…Similarly, widely used imaging modalities such as echocardiography and cardiac magnetic resonance imaging (MRI) are useful in assessing and monitoring phenotypic consequences—including elevations in pulmonary artery pressures and declines in right ventricular systolic function—of pathologic events [ 246 ]. 4D flow MRI is a recent advancement which combines three-dimensional spatial encoding with three-directional velocities to allow for improved hemodynamic assessment, although its application to PAH is in its early stages [ 247 ]. Magnetic resonance spectroscopy (MRS) is an older technology with the ability to provide add molecular quantitation to traditional imaging data, and its experimental use to quantify metabolites in the failing RV suggests that it may have clinical application, as well [ 248 , 249 ].…”

Evaluation of the relationship between pulmonary artery volume and quantitative voxel based flow parameters in patients with and without pulmonary hypertension using 4D flow MRI

“…Several studies have reported the ability of 4D ow MRI to detect and quantify PH based on the wall shear stress (WSS) [7,8] and vortical ow in the pulmonary artery [9][10][11][12][13]. However, the method of quanti cation using this technique is complicated.…”