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@ -102,7 +102,7 @@ University of Groningen\\[0.5cm]
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\frame{\titlepage}
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% \onslide<1->
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@ -131,50 +131,65 @@ University of Groningen\\[0.5cm]
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\begin{frame}
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\frametitle{4D flow MRI}
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\footnotesize
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Main limitation for its clinical applicability is the long scan times involved. Therefore, multiple strategies emerged in order to make acquisition faster>
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Main limitation for its clinical applicability is the long scan times involved. Therefore, multiple strategies emerged in order to make acquisition faster, such as:
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\begin{itemize}
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\item Navigator gating
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\item modest spatial resolutions $2.5 \times 2.5 \times 2.5 \ mm3$
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\item modest spatial resolutions $ \sim (2.5 \times 2.5 \times 2.5 \ mm^3)$
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\item partial data coverage
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\end{itemize}
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Typical quality estimators are> SNR, VNR, peak flows/velocities, mass conservation (zero divergence
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Typical quality estimators: SNR, VNR, peak flows/velocities, mass conservation (zero divergence)
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We want to introduce a novel measure for quantify the quality of the 4D flow measurements, using the conservation of momentum of the flow.
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We want to introduce a novel measure for quantify the quality of the 4D flow measurements, using the conservation of momentum of the flow (Navier-Stokes compatibility).
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\end{frame}
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\section{The corrector field}
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\begin{frame}
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\frametitle{The corrector field}
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\begin{columns}[c]
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\column{.6\textwidth} % Left column and width
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\footnotesize
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\onslide<1-> We assume a perfect velocity \begin{eqnarray*}
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We assume a perfect physical velocity field $\vec{u}$
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\begin{eqnarray*}
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\rho \frac{\partial \vec{u}}{\partial t} + \rho \big ( \vec{u} \cdot \nabla \big) \vec{u} - \mu \Delta \vec{u} + \nabla p = 0 \quad \text{in} \quad \Omega \label{eq:NSmom}
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\end{eqnarray*}
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\onslide<2-> And a corrector field which
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And a corrector field $\vec{w}$ which satisfies:
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\begin{align}
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\vec{u} & \approx \vec{u}_{meas} + \vec{w} \quad \text{in} \quad \Omega \label{eq:corrector} \\
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\nabla \cdot \vec w & = 0 \quad \text{in} \quad \Omega \label{eq:correctorDiv} \\
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\vec w & = \vec 0 \quad \text{on} \quad \partial \Omega \label{eq:correctorBC}
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\end{align}
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\onslide<3-> asd
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$\vec{w}$ measures the level of agreedment of the 4D flow measures respect to the Navier-Stokes equations.
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\end{frame}
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\begin{frame}
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\frametitle{Numerical tests}
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\begin{columns}[c]
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\column{.6\textwidth} % Left column and width
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\footnotesize
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We tested the corrector using CFD simulations as a measurements, in the following testcases:
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\begin{itemize}
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\footnotesize
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\item[]<4-> $u = u_{in} \quad \text{in} \quad \Gamma_{inlet}$
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\item Womersley flow in a cilinder
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\item Navier-Stokes simulations in an aortic mesh
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\end{itemize}
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Also perturbations were added into the measurements:
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\begin{itemize}
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\item velocity aliasing
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\item additive noise
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\item simulated k-space undersampling
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\end{itemize}
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\column{.5\textwidth} % Right column and width
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\footnotesize
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\begin{figure}[!hbtp]
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\onslide<1->
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\begin{center}
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\includegraphics[height=\textwidth]{images/aorta_blender.png}
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\caption{Aortic mesh }
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@ -184,30 +199,17 @@ We want to introduce a novel measure for quantify the quality of the 4D flow mea
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\end{frame}
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\begin{frame}
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\frametitle{The corrector field}
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\frametitle{Experiments}
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\footnotesize
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To study the corrector in several scenarios> synthetic data, experimental phantom and healthy volunteers.
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\begin{itemize}
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\item We performed 4D flow measurements in a silicon aortic phantom
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\item 4 healthy volunteers were scanned using a clinical standard 4D flow protocol.
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\end{itemize}
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\end{frame}
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\begin{frame}
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\frametitle{The corrector field}
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\footnotesize
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different data treatments> aliasing and noise. Undersampling
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\end{frame}
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\section{Results}
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@ -215,7 +217,7 @@ different data treatments> aliasing and noise. Undersampling
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\frametitle{Results}
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\footnotesize
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results for the synthetic data. Comparison againts a perfect correction case with du.
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results for the synthetic data. Comparison againts the perfect correction field: du.
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\end{frame}
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@ -243,10 +245,15 @@ results in healthy volunteers
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\begin{frame}
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\frametitle{Results}
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\frametitle{Conclusions and future}
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\footnotesize
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potential of the new quality parameter> analize real data. use the specificity for label zones with strong disagreedment. Use the field for create new inverse problems which can be used for further accelerations
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potential of the new quality parameter:
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\begin{itemize}
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\item analize real data
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\item use the specificity for label zones with strong disagreedment
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\item Use the field for create new inverse problems which can be used for further accelerations
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\end{itemize}
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\end{frame}
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