How to segment very thin bone structure inside an orbit with low contrast

Hi Everyone,

I have a number of 2D orbital images which I need to segment the thin bones inside. See attached figure :

The white color structures are bones which need to be segmented out. However, as you can see, the bones on the left hand side are quite thin with low contrast and so it often fails to segment out :

I tried to test with Image Segmenter in Matlab App but it often fails to segment neatly, without including other unnecessary structure.

I tried to change the contrast but only those with thick bones are enhanced, not the thin ones. I tried something like this :

BW = img > Threshold;
maskedImage = img;
maskedImage(~BW) = 0;

But the segmented image still have broken lines :

Grateful if anyone can give a feasible solution.