# How to calculate left ventricle ejection fraction?

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Ahmad Alenezi on 20 Sep 2019
Answered: darova on 21 Sep 2019
Hi all
I would like to calculated left ventricle ejection fraction LVEF of the heart from an image set. I have a series of planner images (128x128) (n =16) for one patient (derived from SPECT modality). LVEF is calculated according to the following equation:
LVEF = (Left ventricle end diastolic counts - left ventricle end systolic counts)/ Left ventricle end diastolic counts
Note:
Left ventricle end diastolic counts: is the image of the highest count in the series.
Left ventricle end systolic counts: is the image of the lowest count in the series.
In order to show count from left ventricle only, i drawn ROI around left ventricle and masked all other parts, so that the left ventricle only is visible. I called this serires LVimages.
can you help me on how to do this calculation? note that my image series is called LVimages.
darova on 20 Sep 2019
FOr eahc image you have 128x128 pixels with some values. What do you want to do with pixels? How to find green area?
Ahmad Alenezi on 21 Sep 2019
Edited: Ahmad Alenezi on 21 Sep 2019
I want to know the number of pixels and pixel values within ROIs in all images.

darova on 21 Sep 2019
There is an example with using impoly
imshow(I)
h = impoly; % draw polygon
number = sum(msk(:)); % number of pixels inside polygon
% create (M x N x 3) mask and get values
msk3 = uint8( repmat(msk,[1 1 3]) );
I1 = msk3 .* I;
figure
imshow(I1)