Unit16 image, Pixel values do not equal same values in window

Hi,

I am having trouble getting the value of a pixel in an image that is the same as it is when I use imshow. When I load the image and want to find the value of the pixel at x and y it gives me one answer (image(x,y)) and then when I use imshow then click the data cursor at the same pixel location, I am getting the value Index to be a different number. The index value is the correct number, it corresponds to the native value from the original file before dicoms were written.

I am interested in eventually summing all of the index values for the image.

Any help is greatly appreciated!