Abstract
BackgroundThe purpose of this study was to quantify right (RV) and left (LV) ventricular function, pulmonary artery flow (QP), tricuspid valve regurgitation velocity (TRV), and aorta flow (QS) from a single 4D flow cardiovascular magnetic resonance (CMR) (time-resolved three-directionally motion encoded CMR) sequence in a canine model of acute thromboembolic pulmonary hypertension (PH).MethodsAcute PH was induced in six female beagles by microbead injection into the right atrium. Pulmonary arterial (PAP) and pulmonary capillary wedge (PCWP) pressures and cardiac output (CO) were measured by right heart catheterization (RHC) at baseline and following induction of acute PH. Pulmonary vascular resistance (PVRRHC) was calculated from RHC values of PAP, PCWP and CO (PVRRHC = (PAP-PCWP)/CO). Cardiac magnetic resonance (CMR) was performed on a 3 T scanner at baseline and following induction of acute PH. RV and LV end-diastolic (EDV) and end-systolic (ESV) volumes were determined from both CINE balanced steady-state free precession (bSSFP) and 4D flow CMR magnitude images. QP, TRV, and QS were determined from manually placed cutplanes in the 4D flow CMR flow-sensitive images in the main (MPA), right (RPA), and left (LPA) pulmonary arteries, the tricuspid valve (TRV), and aorta respectively. MPA, RPA, and LPA flow was also measured using two-dimensional flow-sensitive (2D flow) CMR.ResultsBiases between 4D flow CMR and bSSFP were 0.8 mL and 1.6 mL for RV EDV and RV ESV, respectively, and 0.8 mL and 4 mL for LV EDV and LV ESV, respectively. Flow in the MPA, RPA, and LPA did not change after induction of acute PAH (p = 0.42-0.81). MPA, RPA, and LPA flow determined with 4D flow CMR was significantly lower than with 2D flow (p < 0.05). The correlation between QP/TRV and PVRRHC was 0.95. The average QP/QS was 0.96 ± 0.11.ConclusionsUsing both magnitude and flow-sensitive data from a single 4D flow CMR acquisition permits simultaneous quantification of cardiac function and cardiopulmonary hemodynamic parameters important in the assessment of PH.
Highlights
The purpose of this study was to quantify right (RV) and left (LV) ventricular function, pulmonary artery flow (QP), tricuspid valve regurgitation velocity (TRV), and aorta flow (QS) from a single 4D flow cardiovascular magnetic resonance (CMR) sequence in a canine model of acute thromboembolic pulmonary hypertension (PH)
Pulmonary hypertension (PH) is an fatal disease characterized by an abnormal increase in the mean pulmonary artery pressure that leads to right ventricular (RV) failure [1]
In this study we demonstrated the feasibility of measuring RV and left ventricular (LV) function and pulmonary vascular resistance from a single, free breathing 4D flow CMR sequence
Summary
The purpose of this study was to quantify right (RV) and left (LV) ventricular function, pulmonary artery flow (QP), tricuspid valve regurgitation velocity (TRV), and aorta flow (QS) from a single 4D flow cardiovascular magnetic resonance (CMR) (time-resolved three-directionally motion encoded CMR) sequence in a canine model of acute thromboembolic pulmonary hypertension (PH). The initial evaluation of patients with suspected PH includes non-invasive imaging with echocardiography because of its ability to noninvasively estimate pulmonary artery pressures, pulmonary vascular resistance (PVR) and cardiac function [2]. Flow-sensitive CMR sequences can be used to measure pulmonary artery flow (QP) flow and TRV, and thereby estimate PVR (PVRRHC ∝ TRV/Qp) using a method analogous to that used by Abbas et al for echocardiography [5] Using this model, TRV is used as a surrogate of peak systolic pulmonary arterial pressure and reflects the trans-tricuspid gradient. With respect to cardiac size and function, CMR is considered the gold standard for quantification of left [6,7,8] and right [9,10,11] ventricular size and function with time-resolved “CINE” balanced steady-state free precession (bSSFP) imaging due to its high reproducibility
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