How can I determine the area between two boundaries from MRI image? Subject: How can I determine the area between two boundaries from MRI image?

Hi,

This is my first time asking questions here & I'm not also a pro at matlab. I'm posting this since I haven't found any specific answer which solves my problem though I'd already gone through Q&A parts.

My professor assigned me one project which is to extract the cartilage part from MRI image results by using image segmentation. First, I submitted the code which cropped the middle area where cartilage is located and did thresholding to remove some unwanted spots near the cartilage. That code works perfectly for the set of MRI images he gave to me. But the thing is he wants the code which would work for other sets of MRI images he will give me to test in future. (which means I can't expect the cartilage to be at the center of the image)

So now I'm using the follow code which convert the image by gray thresholding.

I = imread('OAI9054866_0015.jpg');

BW = im2bw(I, graythresh(I));

[B,L] = bwboundaries(BW,'noholes');

imshow(label2rgb(L, @jet, [0.5 0.5 0.5]))

hold on

%% Mark the borders with white line

for k = 1:length(B)

    boundary = B{k};

    plot(boundary(:,2), boundary(:,1), 'w', 'LineWidth', 2)

end

This is the original pic >> http://s23.postimg.org/uyyipj7l7/OAI9054866_0015.jpg

This is the pic I got >> http://s2.postimg.org/5ef8mcui1/image.jpg

And my problem is I don't know how to determine cartilage area from the pic I got. As that is pointed by red arrows in the second pic I've attached, if I get the coordinate points along the white borders of the bones, I can crop the area containing the cartilage & my problem will be solved. Please help me out with this if you can folks!!!

Thanks!

Wynn...

[Nitin]

Is the cartilage the whole light blue area or only the section with the arrows?

[Image Analyst]

And eventually you'll find out that graythresh() doesn't pick a good threshold in a lot of images. Are you allowed to have any manual interaction in selecting a threshold or region of interest?

[Wynn Aung]

@Nitin Mahandeo >> The cartilage is the light blue area between two gray bones.

@Image Analyst >> Thanks for your suggestion. Yep I might be able to make some adjustments on thresholding but my professor wants the code which would be able to pick up region of interest (cartilage) automatically.