How to find the maximum density inside a matrix

I threshold a CT scan and then label it using command bwlabel and then complete it using morphological commands.

For the case that there is only one CT scan, I can recognize that it will be like the 91 label for the left lung and the 939 label for the right lung, but in each CT scan these numbers will be different and I intend to do this for 20,000 CT scans. .

What is your suggestion for finding these two numbers in each photo?