Peak velocity estimation in aortic stenosis patients using a fast three-directional two-dimensional phase contrast technique in a single breath-hold: comparison to unidirectional phase contrast MRI and transthoracic echocardiography
Silveira et al. Journal of Cardiovascular Magnetic
Resonance
Peak velocity estimation in aortic stenosis patients using a fast three-directional two- dimensional phase contrast technique in a single breath-hold: comparison to unidirectional phase contrast MRI and transthoracic echocardiography
Juliana Serafim da Silveira 1 2 4
Matthew E Smyke 1 2 4
Rizwan Ahmad 1 2 4
Ning Jin 0 1 4
Debbie Scandling 1 2 4
Jennifer A Dickerson 1 3 4
Carlos E Rochitte 1 4 6
Subha V Raman 1 2 3 4
Orlando P Simonetti 1 3 4 5
0 Siemens Healthcare
1 Columbus , OH , USA
2 Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University , Columbus, OH , USA
3 Department of Internal Medicine/Division of Cardiovascular Medicine, OSU , Columbus, OH , USA
4 Authors' details
5 Department of Radiology, The Ohio State University , Columbus, OH , USA
6 Department of Medicine/Cardiology, InCor Heart Institute , São Paulo , Brazil
-
From 19th Annual SCMR Scientific Sessions
Los Angeles, CA, USA. 27-30 January 2016
Background
Assessment of aortic valve stenosis (AVS) severity is
crucial for valve replacement indication and is typically
performed by transthoracic Doppler-echocardiography
(TTE). However, TTE may be suboptimal in up to 30%
of patients. Unidirectional through-plane phase-contrast
magnetic resonance imaging (1Dir PC-MRI) is the most
common MRI technique used to quantify peak velocities
(Vpeak) and flow (Figure 1A). Nonetheless, 1Dir
PCMRI has been shown to underestimate aortic velocities
if imaging planes are not prescribed exactly
perpendicular to flow direction. Thus, multi-directional velocity
quantification would likely improve the accuracy of peak
velocity measurements, and allow for more accurate
grading of AVS severity. We sought to determine
whether a PC technique capable of measuring 3
directions of velocity in a 2D image plane in a single
breathhold (3Dir PC-MRI) (Figure 1B) provides more accurate
estimation of Vpeak compared to the traditional 1Dir
PC-MRI, using TTE as the reference standard.
Methods
Patients with variable degrees of aortic valvular disease were
prospectively included, and assessed with both TTE and
CMR. 1Dir (TR/TE = 49/2.3 ms, a = 250, BW = 420Hz/px,
segmented GRE) and 3Dir PC-MRI (TR/TE = 49/2.8 ms,
2Dorothy M. Davis Heart and Lung Research Institute, The Ohio State
University, Columbus, OH, USA
Full list of author information is available at the end of the article
a = 150, BW = 1860 Hz/px, segmented EPI) data were
acquired at 3 levels above the aortic valve using a 1.5T
Siemens Avanto. Imaging parameters were: 6 mm slice
thickness, FOV: 380 × 300 mm2, matrix = 192 × 140, Venc
200550 cm/s, prospective ECG triggering, GRAPPA r = 2.
Quantitative image analysis was performed offline using
Matlab (Mathworks, Natick, MA). 3Dir PC-MRI Vpeak was
calculated pixel by pixel using the root sum square of the
three orthogonal velocities (i.e., direction independent
speed). After magnitude and flow thresholding to eliminate
noise, the pixel with the highest velocity within the valve
contour was used for comparison to TTE. Stroke volumes
(SV) were also estimated from through-plane 1Dir and 3Dir
PC-MRI and compared to left ventricular volumes from
SSFP cine imaging.
Results
Forty-one patients were enrolled (25 males, median age
68 years [range 27-85 years]). The average interval
between TTE and CMR was 33 ± 23 days. 1Dir PC-MRI
tended to underestimate Vpeak while 3Dir PC-MRI
measured a higher Vpeak than TTE. Bland-Altman
Plots in Figure 1 C/D illustrate a mean difference of -0.1
m/s and +0.2 m/s for 1Dir and 3Dir PC-MRI,
respectively. Good correlation was observed between both
1Dir and 3Dir PC-MRI SV versus cine SV at all levels
above the aortic valve (rc = 0.85 to 0.89), with a slight
tendency of SV overestimation by 1Dir PC-MRI and
underestimation by 3Dir PC_MRI (Table 1).
rc
0.88
0.89
Plane1
Bias ± SD (ml)
0.88
0.86
Bias ± SD (ml)
4 ± 12
rc: Lin’s Concordance Correlation Coefficient
Conclusions
The higher Vpeak by 3Dir PC-MRI may be explained by
its directional independence, as opposed to 1Dir PC-MRI
and TTE, which can only accurately measure velocity
perpendicular or parallel to the stenotic jet, respectively.
3Dir PC-MRI may therefore offer an advantage over both
1Dir PC-MRI and TTE in the clinical assessment of AVS.
doi:10.1186/1532-429X-18-S1-P335
Cite this article as: da Silveira et al.: Peak velocity estimation in aortic
stenosis patients using a fast three-directional two-dimensional phase
contrast technique in a single breath-hold: comparison to unidirectional
phase contrast MRI and transthoracic echocardiography. Journal of
Cardiovascular Magnetic Resonance 2016 18(Suppl 1):P335. (...truncated)