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, Jan 2016

Juliana da Silveira, Matthew E Smyke, Rizwan Ahmad, Ning Jin, Debbie Scandling, Jennifer A Dickerson, Carlos E Rochitte, Subha V Raman, Orlando P Simonetti

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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)


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Juliana da Silveira, Matthew E Smyke, Rizwan Ahmad, Ning Jin, Debbie Scandling, Jennifer A Dickerson, Carlos E Rochitte, Subha V Raman, Orlando P Simonetti. 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, pp. P335, 18,