Want to find the circular regions

I want to detect circles and remove extra parts with zeros. I tried to detect it using matlab builin function hough transform but it could not detect any cirles. Can anyone suggest me how to detect those circles and remove the others parts (not circles)?

[centers, radii, metric] = imfindcircles(im,[1000 1100]);

Answer 1

[Image Analyst]

Compute the circularities and determine the circularity that is the dividing line between a circle and non-circle

labeledImage = bwlabel(binaryImage);
props = regionprops(labeledImage, 'Area', 'Perimeter');
allAreas = [props.Area];
allPerimeters = [props.Perimeter];
circularities = allPerimeters .^ 2 ./ (4 * pi * allAreas);
acceptableCircs = circularities < 4; % Or whatever works
indexes = find(acceptableCircs);
circBlobsOnly = ismember(labeledImage, indexes);
imshow(circBlobsOnly);