Ultrafast ultrasound using the planar disk method yielded significantly lower absolute errors in regurgitant volume estimation compared to the clinical standard PISA method (9±8 ml vs 31±10 ml, p<0.001).
Does ultrafast ultrasound color Doppler mapping improve the accuracy of regurgitant volume quantification compared to the standard PISA method in an in vitro mitral regurgitation model?
Ultrafast ultrasound color Doppler mapping provides a more accurate estimation of regurgitant volume than the standard PISA method in an in vitro mitral regurgitation model.
Absolute Event Rate: 9% vs 31%
p-value: p=<0.001
Abstract Introduction The regurgitant volume (RVol) is used to decide which patient with mitral valve regurgitation (MR) needs to be referred to invasive therapeutic procedure. It is currently computed with the proximal isovelocity surface area (PISA, fig. 1a) method which uses a single velocity value at the aliasing point (fig. 1b). The RVol is then obtained by integrating all the PISA over time. This method used in the clinic with focused echocardiography is known to underestimate the RVol 1. Ultrafast ultrasound color Doppler can map the flow field of interest at any point in the field of view with high temporal and spatial resolution. In this study, we investigated whether we can improve the precision of the RVol quantification with ultrafast ultrasound with respect to the clinical standard PISA method. Methods In a left heart phantom, different physiological RVols were delivered by a pulsatile pump through a regurgitant orifice. Data were acquired at 6000 frames/s by a conventional cardiac phased array probe (central frequency at 2.75MHz) emitting ultrafast diverging waves, connected to an ultrafast scanner. Power Doppler was first computed to select the area of the image with higher signal (fig. 1c). Color Doppler mapping (fig. 1d) was computed over the systolic phase. A point on the central line in the axis of the orifice was selected in in the convergence zone were the mean velocity was 0.25m/s on average. On this point, RVols were computed as the surface integral of the velocity through a planar disk at the input of the orifice and was integrated over the systolic phase (blue dotted line, fig. 1e) and with the PISA method at this same point (red point fig 1e). The accuracy of the 2 methods were compared by computing the difference in their mean absolute value and percentage. Results RVol estimation using planar disk method yielded statistically significant lower absolute values than the clinical standard PISA method (9±8ml vs 31±10 ml, p0.001; 19±12% vs 73±11%, p0.001) as depicted in fig. 2. Conclusion In conclusion, we could demonstrate a more accurate method to calculate the RVol using the velocity field mapping of ultrafast ultrasound in a MR model.Figure 1 FIgure 2
Buffle et al. (Thu,) conducted a other in Mitral valve regurgitation. Ultrafast ultrasound color Doppler (planar disk method) vs. Clinical standard PISA method was evaluated on Mean absolute error in regurgitant volume estimation (p=<0.001). Ultrafast ultrasound using the planar disk method yielded significantly lower absolute errors in regurgitant volume estimation compared to the clinical standard PISA method (9±8 ml vs 31±10 ml, p<0.001).