Cardiovascular Magnetic Resonance
Evaluation of Aortic Stenosis Severity using
Single Plane Measurement of Effective
Orifice Area
Complementary Information
Standalone Application Manual
Version 1.0
Julio Garcia
Oscar Marrufo
Alfredo Rodriguez
Eric Larose
Philippe Pibarot
Lyes Kadem
January 3, 2012
E-mail: kadem@encs.concordia.ca
Contents
I.
Introduction ........................................................................................................................................................3
II.
Installation ..........................................................................................................................................................3
III. Application user’s guide......................................................................................................................................6
IV. Pseudo Code .....................................................................................................................................................10
V.
Acknowledgements ..........................................................................................................................................11
Figures
Figure 1. Installation file. ............................................................................................................................................4
Figure 2. Matlab components. ...................................................................................................................................4
Figure 3. Installation folder or path............................................................................................................................5
Figure 4. Standalone application file. .........................................................................................................................5
Figure 5. Application main window. ...........................................................................................................................6
Figure 6. Explorer window. .........................................................................................................................................7
Figure 7. Measurement window. ...............................................................................................................................7
Figure 8. Region of interest. .......................................................................................................................................8
Figure 9. Initial points of effective orifice area contour. ............................................................................................9
Figure 10. Effective orifice area (EOA) and stroke volume (SV) computed using AST. ..............................................9
Figure 11. Effective orifice area (EOA) and stroke volume (SV) computed using SPVT. ..........................................10
I.
Introduction
In our article Cardiovascular Magnetic Resonance Evaluation of Aortic Stenosis Severity using Single Plane
Measurement of Effective Orifice Area we introduced two new methods to estimate Effective Orifice Area
(EOA) using a single plane measurement of velocity map. The novel CMR-based methods may be helpful to
corroborate stenosis severity in patients for whom Doppler-echocardiography exam is not conclusive. Both
methods Jet Shear Layer Detection (JSLD) and Single Plane Velocity Truncation (SPVT) were implemented on
one standalone application using Matlab©.
II.
Installation
In order to run as standalone application, we need to install some Matlab components and the implemented
code for EOA measurement using JSLD and SPVT methods. First you need to download the installation file
from our web site: http://users.encs.concordia.ca/~kadem/Research.html ; click on EOA MRI methods on the
left. Please download the installer corresponding to your system characteristics: 32 bits or 64 bits. Note that
32 bit application will work on a 64 bits system. However, 64 bits application will not run on a 32 bits system.
Minimum system requirements are: Windows server 2003 R2, Windows server 2008 R2, Windows XP Service
Pack 2, Windows 7, (all on 32 or 64 bits processors), disk space 1GB for a typical installation and 1024 MB.
Once the installation file is downloaded you may be able to find the folder containing the installation file and
run it (Figure 1). Installation time will depend on your system speed and memory.
Figure 1. Installation file.
The deployment of Matlab components and application will then start. The first component to be installed is
the Matlab compiler runtime (MCR) version 7.16 (Figure 2).
Figure 2. Matlab components.
Please accept the installation license. Matlab compiler installer will ask for the installation path or folder
where it will be installed. You could use the default path or specify one (Figure 3).
Figure 3. Installation folder or path
Once the compiler is installed you can run the standalone application. It will be located in the installation
folder (Figure 4).
Figure 4. Standalone application file.
III.
Application user’s guide
After installing Matlab compiler you may be able to run the standalone application. In the main window, on
EOA methods you can select JSLD method based on acoustical source term (AST) and SPVT (Figure 5).
Figure 5. Application main window.
In both cases you will be allowed to use the explorer file window which is used to navigate on your computer
and load DICOM files (Figure 6). DICOM folders should content only velocity measurements, this application
version does not allow load general DICOM file for measurements but allow their previsualisation. Once you are
located the DICOM folder of your case click on search series. The application will recover all the necessary
information of your case and save it on a file in the same folder. After this operation you may be able to load
your case by clicking on Load Serie. The measurement window will open (Figure 7).
Figure 6. Explorer window.
Figure 7. Measurement window.
On the measurement window you can navigate across your case phases (velocity and magnitude) and
previsualize a video of the cardiac cycle of your case.
For measuring the EOA in using JSLD method based on AST or SPVT method you need to select your phase of
interest (typically peak systole), click on EOA Computation and select Single Phase/Plane. In both methods you
should reduce the field of view before measuring the EOA. To do this select at least three points around your
region of interest (aortic vessel), click on the mouse’s right bottom and select Create Mask. After this operation,
please define the region of interest (usually circular or elliptical) as the inner section of the aortic vessel, click on
the mouse’s right bottom and select Create Mask (Figure 8).
Figure 8. Region of interest.
For JSLD method based on AST you need to define the initial points of contour deployment (Figure 9),
click mouse’s right bottom and select Create Mask. After this step, EOA measurement is computed as well as
stroke volume (SV) in the corresponding phase (Figure 10). For SPVT just aortic vessel region of interest is
needed to compute EOA (Figure 11). For an interactive example, please see the video manual included in our
web site.
Figure 9. Initial points of effective orifice area contour.
Figure 10. Effective orifice area (EOA) and stroke volume (SV) computed using AST.
Figure 11. Effective orifice area (EOA) and stroke volume (SV) computed using SPVT.
IV.
Pseudo Code
The actual application version allows the evaluation of DICOM files from 1.5 T and 3 T Philipps Achiva
imagers. If you want to implement you own application you need to follow the following pseudo code:
Read velocity data set
Compute vorticity using 8-point circulation method as follow (∆ is the spatial resolution) :
1
𝜔𝑧 (𝑖, 𝑗) = 4∆ [(𝑉𝑖,𝑗−1 − 𝑉𝑖,𝑗+1 ) + (𝑉𝑖+1,𝑗 − 𝑉𝑖−1,𝑗 ) + 0.5(𝑉𝑖+1,𝑗+1 − 𝑉𝑖−1,𝑗−1 + 𝑉𝑖−1,𝑗−1 −
𝑉𝑖+1,𝑗−1 )]
Compute acoustical source terme : AST = [∇ ∙ (ωz ˄V)]
Find inflexion points using a contour gradient algorithm (level set or spline).
V.
Acknowledgements
This work was supported by grants from the Canadian Institutes of Health Research, Ottawa, Ontario, Canada
(MOP #79342), the Natural Sciences and Engineering Research Council of Canada, Ottawa (#343165-07), and the
Fondation de l’Institut Universitaire de Cardiologie et de Pneumologie de Québec. Dr. Pibarot is the director of
the Canada Research Chair in Valvular Heart Diseases, Canadian Institutes of Health Research,. J. Garcia and O.R.
Marrufo are supported by CONACYT (Mexico City, Mexico) with PhD grants. Dr. Larose is a Clinical research
scholar of the Fonds de la recherché en santé du Québec.