Download Comparison of stroke volume measurements by cardiac magnetic

Comparison of stroke volume measurements by cardiac
magnetic resonance and right heart catheterization in
patients with pulmonary arterial hypertension
Poster No.:
478
Congress:
ESCR 2014
Type:
Scientific Poster
Authors:
E. A. Mershina, E. Pershina, V. Sinitsyn, T. Martyniuk; Moscow/RU
Keywords:
Cardiac, MR, Comparative studies, Hypertension
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Page 1 of 11
Purpose
In pulmonary arterial hypertension (PAH), cardiovascular magnetic resonance (CMR)
has been proposed as a standard for the assessment of right ventricular function and
characteristics of the pulmonary vascular bed [1, 2]. Accurate assessment of stroke
volume (SV) by CMR is critical in this respect, since earlier studies revealed that SV is
closely related to prognosis and that a change in SV reflects treatment effects [3]. SV can
be assessed by measuring flow in the main pulmonary artery (PA) using phase-contrast
CMR (PC CMR) protocols [6] (Fig. 1 on page 2).
Previous studies have shown that this method is accurate to assess SV measuring PA
flow in healthy subjects [4]. PA velocity profile in PAH patients is non-laminar [5], SV
calculation may be not accurate abd needs to be tested. For this test of accuracy, a
clinical standard is required. This standard is provided by the measurement of SV using
the direct Fick procedure during right heart catheterisation (RHC).
Our aim was to assess the accuracy of SV assessment by measuring flow in the PA using
PC CMR and using volumetric analysis of ventricles (cine CMR) in comparison with RHC
in patients with PAH.
Images for this section:
Page 2 of 11
Fig. 1: Flow curve of the main pulmonary artery (MPA) during a cardiac cycle in a PAH
patient.
Page 3 of 11
Methods and Materials
14 PAH (f/m-9/5, mean age 47,6 years ±12) underwent both CMR and right-sided heart
catheterization. CMR was performed at 1.5T system (AVANTO, Siemens) using velocityencoded MR sequences (PC CMR) and SSFP-cine.
PC CMR was acquired during continuous breathing with velocity encoding perpendicular
to the imaging plane and a velocity sensitivity of 120 cm/sec ( Fig. 2 on page 4, Fig. 3
on page 5 ). Slice orientation was orthogonal to the main PA, slice thickness - 6 mm.
Aortic flow measurement was performed for calculation the ratio between pulmonary and
systemic flow, imaging plane was 2-4 cm above the aortic valve and distal to the coronary
arterial ostia.
CMR-derived SV was measured by PA flow, left (LV) and right (RV) ventricular volumes.
CMR post-processing was performed using the CVI42 software (Fig. 4 on page 6)
No aliasing due to high peak systolic velocities was encountered. The contours of the
PA were automatically traced with manual correction when necessary, simultaneously
on magnitude and velocity-map images of all reconstructed phases. This was done for
every temporal phase, resulting in blood flow as a function of time through the PA.
We measured RV and LV volumes. The endocardial contours of the ventricles were
manually traced on short-axis images in end-diastole
(Fig. 5 on page 7). Papillary muscles were excluded from manual tracing of the
endocardial contours of RV and LV. The ventricular areas were then measured and
ventricular volumes (EDV and ESV) were calculated by adding the ventricular areas and
multiplying by the slice distance.
EDV and ESV were used to calculate LV and RV volumes-derived SV. These SV values
were compared to the SV obtained by invasive Fick method.
Images for this section:
Page 4 of 11
Fig. 2: Double-oblique gradient-echo phase-contrast CMR. Planning of Phase-contrast
cine CMR (PC CMR)
Page 5 of 11
Fig. 3: Double-oblique gradient-echo phase-contrast CMR. Qp, Qs mesuarment
Page 6 of 11
Fig. 4: Double-oblique steady-state free precession cine MR images. The endocardial
boundaries of the ventricles were traced for calculation of EDV and ESV. EDV and ESV
were calculated by summation of the product (area × slice distance) for all slices. SV =
EDV-ESV for RV and LV.
Page 7 of 11
Fig. 5: RV border detection. 4-chambr view was used to determine the level of detection.
Page 8 of 11
Results
Regression analysis has been done, p < 0.0001.
•
•
•
•
•
For SV by PA flow versus Fick, r = 0.41.
For SV by LV volumes versus Fick, r =0.45.
For SV by RV volumes versus Fick, r =0.38.
For SV by aorta flow versus Fick yielded r =0.37.
For SV by PA flow versus SV by RV volumes r=0,7.
Pulmonary to systemic flow ratio (Qp:Qs) more than 1,1 measured by volumetric analysis
(RVSV-LVSV) were found in 2 patients with significant (grade III-IV) tricuspid regurgitation
(Fig. 6 on page 9).
Qp:Qs>1,1 measured by VENC were found in 6 patients including 4 pts with moderate
tricuspid regurgitation and no systemic drainage.
Qp:Qs<1 was found in 1 pts with ASD.
Images for this section:
Page 9 of 11
Fig. 6: Overloaded RV in patient with PAH (EDV RV/BSA=120 ml/m2). Severe tricuspidal
regurgitation.
Page 10 of 11
Conclusion
In conclusion, CMR-derived SV has poor accuracy in PAH patients with a tendency to
overestimate SV value.
Volumetric analysis is more accurate for measurement SV in patients with pulmonary
hypertension.
Despite of poor agreement with invasive data SV calculated using volumetric analysis
could be used for follow-up of PAH patients.
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Page 11 of 11