How to calculate multiple diameter calculation across an image?

I have an image that I convert from a .mat file (size of .mat file is 406x512x380 double) below.

I need to calculate the diameter and it's change across the length of the image measured by the x-axis value (at each section -4, -2, 0, 2, 4 mm) what is the diameter? Here is my current code right now using imdistline() but clearly that is not the most effective when setting multiple locations.

%% pick frame of choice and run grid overlay %%
img = 40;
image = figure('Color', 'k');imagesc(X_1,Z_1,10*log10(R1_contrast(:,:,img)),[115 145]); colormap(gray); % setting colormap to gray
ax = gca;
%axis equal;
h=xlabel('Lateral (mm)'); %or h=get(gca,'xlabel')
set(h, 'FontSize', 16); 
set(h,'FontWeight','bold'); %bold font
z=ylabel('Depth (mm)');
set(z, 'FontSize', 16);
set(z, 'FontWeight', 'bold');
box(ax,'off'); 
set(gca, 'XColor', 'white'); % set x-axis color to white
set(gca, 'YColor', 'white');
set(gca, 'FontWeight', 'bold');
grid on;
axis image;
set(gca, 'GridColor','r', 'GridAlpha',1);
set(gca, 'Layer','top');
imdistline();

[Image Analyst]

Diameter of what? I don't see any distinct circles on your image. And attach your original image, not a screenshot. Like R1_contrast or whatever we'd need to run your code.

[Shelby Hedges]

I tried to demonstrate what the diameter would be with the imdistlin (top white band and bottom white band when looking at the depth axis). I attached the .fig and .png file - sorry for that. The R1_Contrast file is too large to upload.

[Image Analyst]

That does me no good. Can't you attach the image you displayed with imshow()? Without all the red lines, axes, etc.

[Shelby Hedges]

Yes - that was for demonstration purposes. Attached is the original .fig .png files (thanks for your patience/help). Newish to Matlab.