Four-dimensional flow cardiac magnetic resonance assessment of left ventricular diastolic function

Abstract

Left ventricular diastolic dysfunction is a major cause of heart failure and carries a poor prognosis. Assessment of left ventricular diastolic function however remains challenging for both echocardiography and conventional phase contrast cardiac magnetic resonance. Amongst other limitations, both are restricted to measuring velocity in a single direction or plane, thereby compromising their ability to capture complex diastolic hemodynamics in health and disease. Time-resolved three-dimensional phase contrast cardiac magnetic resonance imaging with three-directional velocity encoding known as '4D flow CMR' is an emerging technology which allows retrospective measurement of velocity and by extension flow at any point in the acquired 3D data volume. With 4D flow CMR, complex aspects of blood flow and ventricular function can be studied throughout the cardiac cycle. 4D flow CMR can facilitate the visualization of functional blood flow components and flow vortices as well as the quantification of novel hemodynamic and functional parameters such as kinetic energy, relative pressure, energy loss and vorticity. In this review, we examine key concepts and novel markers of diastolic function obtained by flow pattern analysis using 4D flow CMR. We consolidate the existing evidence base to highlight the strengths and limitations of 4D flow CMR techniques in the surveillance and diagnosis of left ventricular diastolic dysfunction.

Keywords: 4D flow cardiac MR; diastolic function; flow components; heart failure; kinetic energy; vortex.

FIGURE 1

Novel 4D flow CMR parameters of left ventricular diastolic function. Novel 4D flow CMR parameters are obtained from analysis of global flow, vortex flow and/or functional flow components.

FIGURE 2

Peak left ventricular KE/ml in early diastole for healthy individuals with age (30). Early diastolic peak left ventricular KE/ml (generated during active relaxation) declines with increasing age.

FIGURE 3

Left ventricular kinetic energy maps in a control and an MI patient (Top). Kinetic energy curves in a control and two MI patients with preserved left ventricular ejection fraction (pEF) and reduced left ventricular ejection fraction (rEF) showing reduced peak E-wave KE (Bottom) (32).

FIGURE 4

3D volume rendering of turbulent kinetic energy (TKE) (red) in early (E-wave) and late (A-wave) diastolic filling of patients with grade 1 diastolic dysfunction (relaxation abnormality)-top, and grade 3–4 (restrictive filling)-bottom, showing significantly greater turbulent kinetic energy with greater diastolic dysfunction (42).

FIGURE 5

Left ventricular diastolic vortex ring in a healthy volunteer. Example of early diastolic vortex ring (A), Streamlines superimposed on a vortex in a four-chamber view (B) (41).

FIGURE 6

Streamline visualization with velocity color coding of diastolic flow in controls, COPD patients with and without left ventricular diastolic dysfunction (LVDD) (Top row). Streamline visualization of diastolic flow with superimposed vorticity vector fields (Middle row). Vorticity vector fields in all three groups, showing a loss of vorticity in both COPD with and without LVDD (Bottom row) (68).

FIGURE 7

Constituent functional flow components of left ventricular blood volume.

FIGURE 8

Left ventricular blood flow component distribution in healthy controls and in chronic ischemic heart disease patient subgroups (stratified by LVEDV index) (75).